Hardness testing with Zwick

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FP 303 2.1208

Hardness testing with Zwick

Intelligent testing

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The Zwick Roell Group –

over a hundred years' materials testing experience

Mechanical testing is the oldest branch of materials testing and one which has continued to gain in importance. As early as the 15th and 16th centuries, Leonardo da Vinci and Galileo Galilei were considering matters such as the bending load and elastic properties of materials. The first such testing machines appeared in France in the middle of the 18th century.

The Swiss, later German company Amsler began materials testing in the mid-19th century, followed by Roell &

Korthaus in 1920, while mechanical-testing specialists Zwick had been making hardness testers and materials testing machines and systems since 1937. In July 2001 the group was reorganized as a corporation under the name of Zwick Roell AG, which today includes Zwick, Toni Technik, Indentec Ltd and Acmel Labo.

Zwick Roell AG's expertise in the field of force and extension measurement was reinforced by the acquis- ition in 2006 of the Austrian company Meßphysik, followed by the German firm GTM in 2007. Together, these companies provide a comprehensive, co-

ordinated component and function-testing programme – from manually operated or fully automated hardness testers to static and dynamic integrated laboratory testing systems for process-parallel applications.

Zwick's comprehensive and innovative hardness testing solutions

The success of our hardness testing machines and instruments is founded on many years' experience, on our role as a global supplier and on maintaining close contactwith our customers. The versatility and high levelof 'intelligence' of our testing systems are the product of up-to-date engineering, powerful electronics and application-orientated software.

But the Zwick Roell Group is far more than just a supplier of testing equipment, having received EN ISO 9001 certification as long ago as 1994 – a guarantee of product and service quality.

Zwick hardness testing systems Cost-effectiveness:

• co-ordinated solutions for standard applications

• universal application – goods inwards, production control, research and development

• optimum cost/performance ratio in any situation Flexibility through modular construction:

• modular design of hardness testers, machines and accessories offers optimum custom-made solutions to any testing assignment

• upgrading/retrofitting options make our systems future proof

• robust delivery times Versatile accessories:

• hardness-testing devices to standard and customer- specified requirements

• indentors to suit any established testing method

• a range of prismatic specimen supports and holders

• manual and motorized compound tables

• a range of specimen vices

• certified hardness comparison platens Support before and after purchase:

• expert on-the-spot help and advice

• testing in our applications laboratory

• hotline support and service

• comprehensive customer-focused cover provided by more than 56 agencies worldwide

Fig. 1: Zwick Roell AG/Zwick GmbH & Co. KG Administration building, Ulm

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Innovative hardness testing

Zwick has been supplying stationary hardness testing devices for all standardized methods for many years, plus a wide range of portable hardness testers. Through our active involvement in national and international standards committees we are helping to shape modern, innovative hardness testing – for both today and

tomorrow.

A policy of innovative development has seen our hardness product range greatly expanded, particularly in the last few years. The Zwick Roell Group has probably the most comprehensive selection of hardness testing machines and instruments available – for almost any situation.

Stationary hardness testing machines and instruments for the following methods:

• HV – Vickers

• HB – Brinell

• HK – Knoop

• HM – Martens (instrumented indentation testing,formerly HU – universal hardness)

• HR – Rockwell (scales A...K, N, T)

• H – ball indentation hardness

• HVT – modified Vickers method

• HBT – modified Brinell method

• testing hardness of special materials, e.g. carbon- based materials, carbon brushes, plaster, asphalt;

hardness of resilient floor coverings

Portable hardness testers for the following methods:

• Shore, IRHD

• HL – Leeb

• HB – Brinell

• HR – Rockwell

Zwick solutions - customer benefits

Zwick offers a complete range of hardness-testing machines and instruments, from fully automated systems to basic instruments for standard applications. Our hardness testing machines use innovative technologies from our materials testing range in conjunction with hardness testing add-ons and Zwick's testXpert^® software.

Flexibility and upgradability, particularly with the zwicki-

• combination of hardness measuring head with a high- precision measuring microscope, giving hardness testing with optical indentation measurement and digital depth measurement

• compound tables with manual or motorised control

• application-orientated master and standard testing programs in testXpert^®

Features of our hardness testing machines:

• modular design allowing flexible combinations

• virtually unlimited upgradability and expandability

• can be automated and integrated into automatic testing systems

• state-of-the-art digital measuring and control technology as standard

• used in production control, quality assurance and research and development

• your guarantee of a secure, future proof investment Hardness testers – a broad spectrum of uses:

• standardised applications

• with line display and integrated standardized conversion functions to other hardness scales for standard applications

• with touchscreen, extended functions and comfortable operation for a wide range of testing assignments, including batch testing and production control Our hardness testers are characterized by:

• straight forward operation

• automatic test cycle

• manual or automatic load changing

• flexible/large test area height

Fig. 2: Different specimen for hardness tests

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Fig. 1: Overview of hardness testing methods

Hardness testing – basic principles, methods and standards

Basic principles

Around 1900 Martens proposed the following definition:

“Hardness is the resistance of a body to penetration by a second (harder) body.“ This simple, graphic definition became accepted in technical circles and is still used today. Technical hardness is a mechanical

characteristic used to describe a material or the state of a material.

Hardness cannot be measured directly, but is derived from primary measured variables including:

• test load

• indentation depth

• indentation area.

Depending on the test method, the hardness value is determined from one of the following:

• test load plus a geometrical value describing the indentation, e.g. indentation depth

• solely via a length characterizing the indentation

• through a different material response, e.g. scorability.

Hardness values can only be compared if they have been determined by the same test method using identical test parameters.

An unequivocal hardness value can only be determined using the following criteria:

• definition of hardness value

• indentor geometry and material

• size of test load and duration of effect plus means of application

• condition and surface quality of specimen Selecting hardness testing method – principal factors:

• cost-effectivenesss

• cost/effort involved in specimen preparation

• availability of machines and instruments

• standardized specifications Additional factors:

• specimen material and hardness

• shape, dimensions, weight

• accessibility of specimen

• nature of test (e.g. series or hardness sequence testing)

• permissible measurement uncertainty

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For metals, methods involving static force application are usually employed. An indentor (ball, cone or pyramid) made of steel, hard metal or diamond is pressed into a specimen supported on a firm base. The test load is applied perpendicularly, without shock, and with a defined initial application time and duration.

With many test methods, the indentation is measured after removal of the load. The length measurement values(indentation depth, diagonals, diameter) are used to calculate the hardness value.

Fig. 2: Zwick/ZHU0.2/Z2.5 universal hardness testing machine with HU measuring head, microscope and motozried compound table.

Fig.1: Zwick/ZHV1 micro Vickers hardness tester with motor operated cross-table.

In practice the Rockwell, Brinell and Vickers (Knoop) hardness testing methods are used, with the modern instrumented indentation method (Martens hard- ness) gaining steadily in significance. This method is seeing increasing use in research and development and industry, as it offers the capability to determine other materials parameters in addition to hardness.

Moreover, this method can be employed with any material.

Zwick is playing a leading role in this innovative testing method, in collaboration with the German Institute of Material Research (BAM), and is actively involved in national and international standards committees in this field.

Hardness testing methods featuring dynamic force

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Hardness testing methods and standards Rockwell hardness testing

(A, B, C, D, E, F, G, H, K, N, T)

Measured quantity Rockwell hardness HR.

Indentation depth h in mm

Definition HR = N - h/S

N ... numerical value (specified for each Rockwell method) h ... residual indentation in mm S ... scale value in mm.

This value is the change in indentation in mm corresponding to one Rockwell unit.

Explanation of test result display:

e.g. 61,2 HRC

Code letter for selected Rockwell method Code letters for Rockwell hardness Hardness value

Advantages

• test requires little time as the hardness value can be read off directly following indentation (or is displayed)

• capable of automation

• low capital cost of testing machine as no optical measuring unit is required

• no operator influence - hardness value displayed directly

Disadvantages

• possibility of error during test sequence due to permanent displacement of specimen and other components in force flow

• limited capability for testing specimens with hardened edge layers due to high test loads involved

• diamond indentor sensitive to damage, with consequent risk of measuring errors

• poor hardness differentiation

• influence of indentor on test result when using a conical indentor

Relevant standards

• EN ISO 6508

• ASTM E 18

Vickers hardness testing

Measured quantity

Vickers hardness HV. Lengths of both diagonals of residual test indentation measured.

Definition HV = 0.102 F/A

= 0.1891 F/d² F ... test load in N

A ... indentation surface in mm² d ... arithmetic average value of diagonal lengths.in mm

e.g. 230 HV 10/20

Indentation duration in s (not required for standardised duration)

Code number for test load corresponding to F in N · 0.102

Code letters for Vickers hardness Hardness value

Advantages

• virtually no limit imposed on use of method due to specimen hardness

• can be used for tests on thin sheet-metal, small specimens or test areas, thin-walled pipes and electroplating

• hardness value not dependent on test load in macro range (test loads > 49 .03 N)

• no measuring errors due to limited specimen elasticity in effective test force direction

Disadvantages

• difficult to obtain adequate surface quality

• measurement of diagonals time-consuming

• diamond indentor sensitive to damage

• susceptible to vibrations, especially in micro range

• operator influence on hardness value

• EN ISO 6507

• ASTM E 92

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Knoop hardness testing

Measured value

Knoop hardness HK. Length of long diagonals from residual test indentation measured.

Definition HK = 0.102 F/A

= 1.451 F/d² F ... test load in N A ... projection area of test indentation in mm²

d ... length of long diagonals in mm

Brinell hardness testing

Measured value

r Brinell hardness HB. Two diameters (at right angle)s of the residual indentation in the specimen surface r measured.

Definition HB = 0.102 F/A

= 0.102 · 2F/ (p D(D- vD²-d²)) F ... test load in N

A ... indentation surface in mm² D ... Ø of ball indentor in mm d ... arithmetical average of two measured indentation diameters in mm

e.g. 1240 HK 0,5/30

test duration in s (n/a for 10 - 15 s) code number for test load corresponding to F in N · 0.102

code letters for Knoop hardness hardness value

Advantages

• suitable for narrow specimens due to high diagonal length ratio of approx. 7:1

• superior to Vickers method for thin specimens or layers, owing to reduced indentation depth (by a factor of 4) for the same diagonal length

• suitable for brittle materials due to low risk of cracking

• suited to investigation of anisotropy of a material, as Knoop hardness in such cases is dependent on the direction selected for the long diagonals

• no impairment of test surface functionality due to shallow indentations

Disadvantages

• considerable time required to obtain a sufficiently fine test surface

• hardness dependent on test load

• diamond indentor susceptible to damage

• time-consuming alignment of test surface to obtain

e.g. 205 HBW 10/3000/30

test duration in s (n/a for

standardised durations of 10 - 15 s) code number for test load, corresponding to F in N · 0.102 diameter of ball indentor in mm code letter for indentor ball material (hard metal)

code letter for Brinell hardness hardness value

Advantages

• suitable for hardness tests on inhomogeneous materials (owing to large indentation), provided the extent of the inhomogeneity is small in relation to the indentation

• suitable for hardness tests on large unfinished components such as forgings, castings, hot-rolled, hot-pressed and heat-treated items

• no measuring errors due to specimen elasticity in effective force direction

• simple, robust indentors

Disadvantages

• range of applications limited at a maximum Brinell hardness of 650 HBW

• of limited use for testing small or thin-walled specimens

• measuring indentation diameters is time-consuming

• relatively high level of damage to specimen during

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h_p h_r h_max h FmaxF

a c b

1 2

3

hp hc hmax

Instrumented indentation testing (Martens)

Measured value Test load and associated (synchronous) indentation depth during loading and load removal are measured.

Definition 1 indentor

2 surface of residual plastic indentation in specimen 3 surface of indentation at

maximum indentation depth and test load

a test load application b test load removal

c tangent to curve b at Fmax

This testing method is also referred to as an instrum - ented test to determine hardness and other materials parameters. The result of the test is the continuous load-indentation depth curve during the complete test cycle. By analyzing this curve at several points,

comprehensive mechanical materials properties can be determined – within the scope of a single test.

Derivable materials parameters

• Martens hardness HM

• volume hardness HM S

• indentation hardness H IT

• elastic indentation modul us EIT

• creep CIT

• relaxation R IT

• indentation work (elastic, plastic)

• local Martens hardness via indentation depth Zwick Martens testing systems offer you:

• use in the macro range with test loads from 2N to 2500 N with indentation depths > 6 µm and indentors with various geometries (Vickers, Berkovich, various ball shapes, …)

• flexible testing parameters with regard to load application, holding and load removal – position or load-controlled

• standardized assessment criteria for calculation of results – definitions of the approximation curve, beginning and end of elastic resilience, and interval for volume hardness

• automated cyclic indentation testing to determine machine compliance – evaluation of all unloading surges in the testing cycles

• automatic determination of machine elasticity, with graphic presentation

• testing program (optional) for cyclic indentation testing to obtain experimental data as the basis of the new R&D field 'Simulation of strength values from instrumented indentation testing'

e.g. HM 0,5/20/20 = 8700 N/mm²

hardness value test load dwell time in s test load application time in s test load in N

Advantages

• suitable for all materials

• determination of hardness value from elastic and plastic deformation

• additional characteristics data on mechanical material properties available (material relaxation/ creep, elastic and plastic proportion of indentation work, plastic hardness, elastic indentation modul us)

Disadvantages

• decreasing the degree of indentation places increas – ed demands on the quality of the specimen surface (indentation depth = 20 · average surface value)

• susceptible to vibrations, particularly in indentation range h < 15 µm

• possibility of error due to elastic and permanent displacement of specimen and of components in the force flow during test cycle

• EN ISO 14577

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Modified Brinell HBT method

Measured value

Modified Brinell hardness HBT.

Residual indentation depth h from test indentation under pre-load measured in mm.

Definition

HBT = hardness value, converted from indentation depth using a reference specimen.

e.g. 205 HBT 10/3000

calibration method for reference specimen code letters for test method

hardness value

Advantages

• only short time required for test, as hardness value can be read off / is displayed directly following indentation

• no operator influence -hardness value displayed directly

• test surface requires little preparation Disadvantages

• conversion ratio has very restricted validity

• possibility of error during test cycle due to permanent displacement of specimen and other components in force flow

• comparison measurements on different machines assume a common conversion factor

• method not standardi zed Non-standardized method to:

VDI/VDE 2616-1 Modified Vickers HVT method

Measured value

Vickers hardness from HVT depth measurement

Indentation depth h under test load.

Definition HVT = 0.102 F/A

= 0.102 F/ (26,43 h²) F ... test load in N A ... indentation surface in mm²

h ... indentation depth under test load in mm

e.g. 320 HVT 10/20

indentation duration in s

code number for test load corresponding to N · 0.102

code letters for Vickers depth hardness hardness value

Advantages

• suitable for all materials

• can be used in production control

• determination of hardness value from elastic and plastic deformation

Disadvantages

• decreasing degree of indentation places increased demands on quality of specimen surface (indentation depth = 20 · average surface value)

• susceptible to vibrations, particularly in indentation depth range h < 15 µm

• sensitive to shape deviations in indentor, particularly in tip area

• method not standardi zed Non-standardized method to:

VDI/VDE 2616-1

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Rebound hardness test

Measured values

Rebound hardness. Impact velocity va and rebound velocity vr (or height) of impact body are measured.

Definition

Rebound hardness = c · vr / va c ... constant

vr ... rebound velocity of impact body

va ... impact velocity of impact body

e.g. 540 HL

code letters for rebound hardness hardness value

Advantages

• portable device, simple to operate

• automatic test sequence; very short test time

• testing in any position, e.g. overhead

measurement possible using correction factors Disadvantages

• testing thinner specimens or specimens with low mass poses problems

• high level of operator influence possible Relevant standards

• ASTM Standard A 956

dynamic measuring methods: quotient of rebound (Rp) and impact (Ap) velocity with hardness expressed in Leeb: HL

• DIN 50156

UCI method (Ultrasonic Contact Impendance)

Specimen hardness calculated from known test load, measured frequency shift and stored adjustment values, with reference to the E modulus.

A rod is excited into longitudinal oscillations. At one end there is a Vickers diamond, which is pressed into the material under test. The defined load F is mostly applied via a spring. The rod oscillates at its natural resonance frequency, which essentially depends on its length. Pressing the Vickers diamond into the specimen causes damping of the oscillation. Linked to this is a shift in the resonance frequency, which is measured. The damping of the rod, and the associated frequency shift, depends on the contact area between diamond and specimen and, given a fixed test load, on the hardness of the specimen. The E modulus of the material under test also influences the frequency shift.

Advantages

• mobile, flexible in use

• testing in any position

• simple to operate Disadvantages

• testing thinner specimens or specimens with low mass can be difficult. The testing requires a minimum thickness as well as a minimum mass in order to achieve reliable results. In certain cases the acoustic attatchment onto larger masses could improve the results.

• The Ultrasonic Contact Impedance method is standardised to ASTM A 1038

• DIN 50158

Load F

F Sender

Receiver

Oscillation

Diamond

Hardness HV Hardness = f (F, Δf)

Δf Calibration line Resonance- amplifier

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Summary chart: hardness testing on metals

Table 1: Overview of metals standards and methods Method

Rockwell Scale A

Scale B

Scale C

Scale D

Scale E

Scale F

Scale G

Scale H

Scale K

15 N 30 N 45 N

15 T 30 T 45 T

Standard

EN ISO 6508-1 EN ISO 6508-1 EN ISO 6508-1 EN ISO 6508-1 EN ISO 6508-1 EN ISO 6508-1 EN ISO 6508-1 EN ISO 6508-1 EN ISO 6508-1 EN ISO 6508-1

EN ISO 6508-1 Test load

98.07 N

29.42 N 29.42 N 29.72 N

29.42 N 29.42 N 29.42 N Abbre-

viation HRA

HRB

HRC

HRD

HRE

HRF

HRG

HRH

HRK

HR 15N HR 30N HR 45N

HR 15T HR 30T HR 45T

Indentor

Diamond cone

Ball, Ø 1.5875 mm (1/16 inch) Diamond cone

Diamond cone

Ball, Ø 3.1750 mm (1/8 inch)

Ball, Ø 1.5875 mm (1/16 inch) Ball, Ø 1.5875 mm (1/16 inch)

Ball, Ø 3.1750 mm (1/8 inch)

Diamond cone Diamond cone Diamond cone

Ball, Ø 1.5875 mm (1/16 inch)

Total test load 588.4 N

980.7 N

1471 N

980.7 N

588.4 N

1471 N

588.4 N

1471 N

147.1 N 294.2 N 441.3 N

Measurand

& range

Rockwell hardness HR 20 ... 88 HRA

20 ... 100 HRB

20 ... 70 HRC

40 ... 77 HRD

70 ... 100 HRE

60 ... 100 HRF

30 ... 94 HRG

80 ... 100 HRH

40 ... 100 HRK

70 ... 94 HR 15 N 42 ... 86 HR 30 N 20 ... 77 HR 45 N

67 ... 93 HR 15 T 29 ... 82 HR 30 T 1 ... 72 HR 45 T

Rockwell testing method Applications

HRA Can test hardened and hardened tempered steels with low thickness or thinner edge layer than HRC Reduced material stress and specimen damage compared with HRC. Hard metals .

HRD Surface-hardened parts with medium hardness layers.

HRC Hardened and hardened tempered steels (tools, high-strength mild steels).

HRF Cold-rolled thin steel sheet,annealed copper-zinc alloys and annealed copper . HRB Soft mild steels (sheets, non-ferrous metals ).

HRG Phosphor-bronze, beryllium copper, low-hardness malleable cast iron . HRH Aluminium, zinc, lead.

HRE Cast iron, aluminium and magnesium alloys, bearing metals.

HRK Bearing metals and other metals with very low hardness.

HR 15/30/45 N Steels as per HRA, HRD und HRC, provided thin parts or edge layers are involved.

HR 15/30/45 T Soft steels and non-ferrous metals as per HRF und HRB, provided items are thin (e.g. deep-drawn sheets) Table 2: Overview of applications for Rockwell testing

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Summary chart (continued): hardness-testing on metals

Table 1: Overview of metals standards and methods

Degree of loading 30 10 5 2.5 1

Indentor ball Ø in mm Test load F in N

10 29420 9807 4903 2442 980.7

5 7355 2452 1226 612.9 245.2

2.5 1839 612.9 306.5 153.2 61.29

1 294.2 98.07 49.03 24.52 9.807

Recordable hardness range 96-650 32-218 16...109 8...55 3...22

Examples Steel, (mallea- Aluminium, brass, Aluminium, zinc Aluminium Lead, tin ble) cast iron copper, bronze

Method Brinell

Abbreviation

HBW

Indentor

Ball,

Ø 1/2.5/5/10 mm

Test pre-load -

Total test load 9.8... 29420 N

Measurand

& range Brinell HB

Standard

EN ISO 6506-1

Method

Instrumented indentation test (Martens hardness)

HVT method

HRT method

Abbreviation

HM

HVT

HBT

Indentor

Diamond pyramid, face angle 136°

Berkovich diamond pyramid, hard-metal balls

Diamond pyramid 136°

Ball,

Ø 2.5/5/10 mm

-

~1.96

1961 N;

980.7 N;

490.3 N;

98.07 N

Total test load 2...2500 N

2...2500 N

1.961 ...

980.7 N

29420 N ...

612.9 N

Measurand

& range

HM in N/mm² HM in N/mm²

Vickers HVT

Brinell HBT,

≤ 650 HBT

Standard

EN ISO 14577

Method not standardized;

HVT according VDI/VDE 2616-1

Method not standardized;

HBT according VDI/VDE 2616-1 Method

Vickers Micro Low-load Macro

Knoop

Abbreviation

HV 0.01...≤ 0.2 HV 0.2...≤ 5 HV 5...100

HK

Indentor

Diamond pyramid, face angle 136°

rhombic diamond pyramid

Test pre-load

- - -

-

Total test load

0.098...1.961 1.961...49.03 49.03...980.7 N

≤ 9.807 N

Measurand

& range

Vickers HV Vickers HV Vickers HV

Knoop HK

Standard

DIN ISO 4516, EN ISO 6507-1

ISO 4545 DIN ISO 4516

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Converting hardness values

Sometimes it is necessary to convert values obtained by one method into those of another method. This is generally because a testing machine for the desired method is not available, or when, for example, there is not enough room on the specimen for indentations using the preferred method.

Given the locally differing hardnesses in many materials, such conversions only provide a rough indication of the actual hardness and should only be used when there is a sufficient certainty of obtaining an accurate conversion.

Empirical conversion ratios exist between the Brinell, Vickers and Rockwell methods and between hardness and tensile strength. These are for certain materials only and have limited accuracy. General conversion ratios do not exist.

Details are available from Standard EN ISO 18265 (formerly DIN 50150). For non-ferrous metals, further information can be found in ASTM E 140.

Summary chart (continued): hardness testing on metals

Rule-of-thumb (for estimations)¹: HB ↔ HV: HB ≅ 0,95 x HV

HRB ↔ HB: HRB ≅ 176 - 1165/√– HB HRC ↔ HV: HRC ≅ 116 - 1500/v–

HV

HV ↔ HK: HV ≅ HK (low load range )

R_m↔ HB, HV: Rm≅ c HB (oder HV), Rm in N mm^-2 Factor c for estimation of tensile strength R_m given in most literature as:

c ≅ 3.5 for steel (bcc-Fe-matrix ) c ≅ 5.5 for Cu and Cu-alloys (annealed) c ≅ 4.0 for Cu and Cu-alloys (cold-formed) c ≅ 3.7 for Al and Al-alloys

1... from: Blumenauer, H.: Werkstoffprüfung, 6th edition, 1994 Method

Rebound hardness testing (Leeb)

UCI-Method

Abbreviation

HL

-

Indentor

spherical,

radius 1.5 ... 2.5 mm

Diamond pyramid

-

Total- pre-load

E = 3.0 mJ ...

90.0 mJ

10, 49, 98 N

Measurand

& range

Rebound hardness

UCI

Standard

conforms to VDI/VDE 2616-1 ASTM A 956 DIN 50156

DIN 50158 Table 1: Overview of metals standards and methods

diamond

topaz corundum

quartz orthoclase apatite fluorite calcite

gypsum

hard metals chromium-hardened tool steel

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Hardness testing machines and instruments

Hardness testing machines comprise zwicki-Line materials testing machines with a range of hardness testing add-ons plus Zwick's testXpert^® software. Load application is controlled by the testing machine and the testXpert^® software in closed loop mode.

Digital measuring and control technology comes as standard with the hardness testing machines and enables test sequence parameters to be reproduced with a high level of precision. Options providing optimization of individual test cycles are a highly important aspect of testing machine automation.

Zwick hardness testing machines can be divided into two main groups:

1. Machines based on the zwicki-Line and focused to use in research and development and quality

assurance:

• ZHU0.2/Z2.5 – universal hardness testing machine with HU measuring head up to 200 N

• ZHU2.5/Z2.5 – universal hardness testing machine with HU measuring head up to 2500 N

• ZHV20/Z2.5 – low-load Vickers tester up to 20 kgf

• ZHV30/Z2.5 – low-load Vickers tester up to 30 kgf

2. All-purpose group of testing machines are also based on closed -loop technology and cater for quality and production control:

• ZHU250 – universal hardness tester ( matt screen) up to 250 kgf

• ZHU250top – universal hardness tester (TFT, PC technology) up to 250 kgf

• ZHU750top - universal hardness tester (TFT, PC technology) up to 750 kgf

• ZHU3000top - universal hardness tester (TFT, PC technology) up to 3000 kgf

Our self-contained hardness testing instruments can be set up for a particular testing method. They are used in R&D and for production control and quality assurance:

• ZHV1/ZHV2 – micro Vickers hardness tester up to 1 (2) kgf

• ZHV10 – low-load Vickers hardness tester up to 10 kgf (optional 30 kgf)

• ZHV30 – low load Vickers hardness tester up to 30 kgf

• ZHR – Rockwell hardness testers

Zwick Roell Group's hardness testers and testing machines are your guarantee of a secure, long-term, futureproof investment.

Fig. 2: Zwick/ZHU250top universal hardness testing machine in dark field mode with testXpert^® II link

Fig. 3: Zwick/ZHV1 micro Vickers hardness testingin strument with motor-operated compound table and testXpert^®

Fig. 1: Zwick/ZHV20/Z2.5 low-load Vickers hardness testing machine with motor-operated compound table and testXpert^®

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ZHU/zwicki-Line universal hardness testing machines

The ZHU/Z2.5 universal hardness testing machines can be used for all the classical testing methods, including Rockwell, Vickers, Knoop, Brinell and ball indentation hardness. They are also well-suited to the innovative instrumented indentation testing method. This is used to determine hardness plus additional metallic materials parameters and is referred to as Martens hardness (EN ISO 14577).

The ZHU/Z2.5 features a patented hardness measuring head (resolution 0.02 µm) with integrated digital depth and force measuring system, mounted in a zwicki-Line materials testing machine with modified drive. Add to this our state- of-the-art measuring and control electronics testControl and our intelligent test software testXpert^® and the result is a well-balanced, high precision measuring system.

Fig. 2: Zwick/ZHU2.5/Z2.5 universal hardness testing machine with hardness measuring head

• Rockwell hardness HR scales R, L, M, E, K, a

• Vickers depth measurement HVT

• Brinell depth measurement HBT

• Ball indentation hardness H (for plastics)

Optical methods using the Zwick ZHU optical unit

• Vickers HV

• Brinell HB

• Knoop HK

Two different test areas are available with the ZHU/

zwicki-Line: 350 mm or 850 mm.

To facilitate high-precision measurements in various application areas, 2 hardness measuring heads with exchangeable indentors and transducer foot are

available:

2 N … 200 N or 5 N … 2.5 kN

Also available is an add-on optical unit which, when used with the hardness measuring head, allows any current hardness method to be employed. The optical unit consists of a measuring microscope with up to 4 lenses. It also has a manual operated linear displacement unit designed to allow microscope and load assembly to exchange positions. This avoids the need to move components waiting to be tested. The ZHU/zwicki-Line can be upgraded to an fully-automated hardness tester using the motorized linear displacement unit (MLDU), actively controlled by testXpert^®. Therefore potential user influences are totally eliminated.

The application of the intelligent testing software testXpert^® supports the innovative testing systeme in standard tasks (e.g. quality assurance) as well as in research and development for very sophisticated tasks.

The ZHU/zwicki-Line range is complemented by a comprehensive, standardised range of

Fig. 1: General layout of HU hardness measuring head

housing

load measuring system (1% fnom, class 1) indentation depth measuring system indentor

sensor foot

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Fig. 2: Zwick/ZHU0.2/2.5 in hot cell for testing radioactive material

The ZHU/Z2.5 range features:

• user-friendly one-button operation

• universal application for practically any hardness testing method using indentation depth measurement, regardless of material

• fast, automatic approach, even with varying specimen heights

• automatic test sequence and evaluation

• shortest possible testing times

• minimum changeover time from one method to another or when exchanging indentor and transducer foot

• high level of precision and reproducibility of measured values due to high test data resolution and constant testing conditions

• additional materials data obtained from force/

indentation test profile

• versatile result presentation: single and statistical values, graphics, on-screen display, and print-outs can be varied as required

Fig. 1: Zwick/ZHU2.5/Z2.5 universal hardness testing machine with hardness measuring head and optical add-on unit

• multiple curve overlay for direct comparison of series tests

• configuration of user-specific test sequences; even special test sequences are easy to define and execute

• can be used for production-line testing.

Fig 3: Fully-automated universal hardness tester Zwick/ZHU2.5/Z2.5 with motorized linear dispacement unit (MLDU)

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Fig 2: ‘Revolver’ holding 4 indentors and 2 lenses

Zwick/ZHU topline universal hardness testing machine (up to 3000 kgf test load) Today's modern all-purpose hardness testing machines are based on technologies making innovative use of mechatronic components. Their high level of precision gives them a wide range of applications, particularly in quality assurance, production-line checks and in the laboratory environment.

Zwick manufactures three ZHU topLine hardness testers:

ZHU250top (1 – 250 kgf / 9 .8 – 2452.5 N) ZHU750top (3 – 750 kgf / 29 .4 – 7357.5 N) und ZHU3000top (20 – 3000 kgf / 196 .2 – 29430 N) . All use innovative optical zoom technology, thus eliminating the need for frequent lens changes. The closed loop/load cell load application technology provides solutions for both optical and depth measurement testing in accordance with recogni zed testing methods.

Optical methods

• Vickers (HV) EN ISO 6507

• Brinell (HB) EN ISO 6506

• Knoop (HK) ISO 4545

Depth measurement methods

• Rockwell (HR) EN ISO 6508

• Vickers (HVT)

• Brinell (HBT)

• Ball indentation hardness (H) ISO 2039-1for plastics Users quickly become familiar with the intuitive, easy-to- use operating system. Test sequences can be configured individually or easily stored or loaded. In addition to manual indentation measurement, ready integrated, fully automatic image analysis is optionally available, providing intelligent, high-precision measuring and reducing operator influence to a minimum.

Ringlight option

Fig 3: Zwick/ZHU250top universal testing machine with testXpert^® II connection

A further option available is a ringlight using LED technology. This produces a special contrast image to allow more precise, automatic indentation measuring, particularly with softer materials (e.g. < 200 HB), unaffected by loss of clarity due to edge bulging.

'Revolver' option

One very special feature is the 'Revolver' motorised turretavailable with the ZHU250top und ZHU750top. This can hold 4 different indentors and 2 lenses (2.5 / 4 / 10 / 20-fold). Add to this a motorized lead screw (instead of a handwheel) and the result is a top-of-the range hardness tester with a comprehensive range of accessories to suit any application.

Intelligent testing with testXpert^® II (option)

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Fig. 1: Zwick/ZHU250 universal hardness tester linked to testXpert^® II

Zwick/ZHU 250 universal hardness tester Applications

The Zwick/ZHU250 universal hardness tester is used for the following methods:

• Vickers (HV) EN ISO 6507, ASTM E 92

• Knoop (HK) ISO 4545, 4546

• Brinell (HB) EN ISO 6506, ASTM E 10

• Rockwell (HR) EN ISO 6508, ASTM E 18

• Vickers depth measurement HVT VDI/VDE 2616-1

• Brinell depth measurement HBT VDI/VDE 2616-1

• Ball indentation hardness (H) (ISO 2039-1) (plastics) The Zwick/ZHU250's robust design guarantees many years of high-precision testing in a wide range of applications requiring a test load up to 250 kgf. It features quick, easy, precise handling.

Optical measuring of indentations uses a digital precision measuring system on a highly tempered, non-reflective matt screen. A comprehensive range of lenses

(magnifications from 15x up to 520x) and accessories is available to suit any testing situation.

Connection to testXpert^® or testXpert^® II via an RS232 interface.

Zwick/ZHU 187.5 universal hardness tester The Zwick/ZHU 187,5 is available in versions to suit test loads between 29.4 N and 1839 N (187.5 kg) for the following methods:

• Vickers hardness (macro)

• Brinell hardness (up to 1839 N)

• Rockwell hardness (classic method).

Fig. 2: The Zwick/ZHU 187,5 universal hardness tester is available in various versions to suit different load stage combinations.

Features of these instruments include weight-loading, an automatic test cycle and an indentor-carrier providing highly flexible test positions. They are available with an LCD line display. Load-change is by means of side- mounted rotary knobs; the test method is selected via the line display. The microscope has adjustable graticules and the hardness value is transmitted to the testXpert^® software at the touch of a button, to appear

automatically on the display. Statistical evaluations and conversions conforming to testing standards can be performed in addition to entering tolerance limits.

An RS 232 interface plus a wide range of accessories (indentor, support table, hardness comparison blocks) are included as standard.

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Summary of applications: Zwick 3106 Zwick 3106 universal ball-indentation hardness tester

The Zwick 3106 hardness tester has universal application for all depth-measurement tests.

The following can be tested to standard:

• Rockwell hardness (EN 10109-1, EN ISO 6508),

• Rockwell hardness for carbon-based materials (DIN 51917, DIN IEC 413)

• Ball indentation hardness for plastics and hard rubber (ISO 2039-1),

• Hardness test: plaster (DIN 1168-2),

• Indentation test: asphalt (DIN 1996-13),

• Indentation test: resilient floor-coverings (EN 433).

The Zwick 3106 is equipped with a digital gage and an upgrade allows data output to printers and PCs. It is employed in research, development, quality control and for goods inwards.

Fig. 1: Zwick 3106 with integrated digital display and electronic measuring

Method

Rockwell hardness of carbon-based materials

Indentation method on carbon brushes

Hardness testing plaster

Indentation testing asphalt

Indentation test

Stan- dard

DIN 51917

DIN IEC 413

DIN 1168-2 DIN 1996 Teil 13 Abbreviation

HR 10/20 HR 10/40 HR 10/60 HR 10/100 HR 10/150 HR 10/20 HR 10/60 HR 10/100 HR 10/150 H in MN/m²

-

Indentor

Hardened ball, Ø 10 mm (5 mm)

Hardened ball, Ø 10 mm

Ball, Ø 10 mm

Cylinder L = 30mm Ø 11.3 mm Ø 25.2 mm Cylinder

Test pre-load 98.07 N

98.07 N

10 N

25 N

Total test load 196.1 N 392.2 N 588.4 N 980.7 N 1471 N 196.1 N 588.4 N 980.7 N 1471 N 200 N

525 N

Application

Carbon, graphite, metal-graphite materials (carbon brushes)

Natural/metal/

electrographite, hard carbon

Stucco, plaster

Mastic/rolled asphalt

Elastomers, embossed Optional accessories: Zwick 3106

Indentor: normal/short (120° diamon d pyramid) Balls: ø ¹/¹⁶’’, ø¹/⁸’’,ø¹/⁴’’,ø¹/²’’ (Rockwell)

Indentor balls: ø 5/10 mm

Compression die: ø 11.3/25.2/15.97 mm Circular support table : ø 9/48/155 mm

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Fig. 1: Zwick/ZHV1-PC manual micro Vickers hardness tester with testXpert^® connection

Vickers hardness testers

Zwick has a range of Vickers hardness testers to suit every application, covering a wide load range and offering various levels of operator comfort.

Zwick/ZHV1 and ZHV2 micro Vickers hardness testers

Zwick's micro Vickers hardness testers are available in two versions to suit different load ranges: ZHV1 for weights from 10g to 1000g, and ZHV2 for weights from 25g to 2000g. They conform to the following standards:

• Vickers (HV) EN ISO 6507, ASTM E 92

• Knoop (HK) EN ISO 4545, ASTM E 384

For both load ranges there is a choice of operating concept:

ZHV-m (manual) – measuring is performed manually by the operator, using a microscope. The automatic turret allows one-button control of lens and indentor position- change. The automatic test sequence and predeter- mined time frame eliminate operator influence during hold time.

ZHV-PC - the ZHV1 and ZHV2 can be retrofitted with a CCD camera for optical evaluation on a PC system.

Optical measurement of the indentations is then performed manually, or automatically via testXpert^®.

ZHV1-A / ZHV2-A fully automatic:

• Automatic focussing of the indentation controlled by testXpert^®

• 2 versions: 2 different motorised compound tables

• Control of 3 axis (x-y-z)

ZHV1-S / ZHV2-S semiautomatic:

• Manual focussing of the indentation

• 3 versions: one digital or two different motorised compound tables

• Control of 2 axis (x-y)

Motorized load-change, automatic indentation

measuring, automatically controlled turret (via testXpert^®) for changing indentor position and lens positions,

motorized compound table and fully automatic test sequences – uses include hardness profile tests with multiple sequences.

Fig. 2: Zwick/ZHV2-a fully automatic micro Vickers hardness tester with motorized compound table

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Zwick/ZHV10 low-load Vickers hardness tester The Zwick/ZHV10 Vickers hardness tester has a proven track record, especially with:

• Vickers hardness

• Knoop hardness

• Brinell hardness

• case-hardening, hardening and nitriding depth

• scratch hardness according to Mohs (analog unit only).

Loading weights from 0.2 kg to 10 kg (option up to 30 kg) and exchangeable lenses for various magnifications and image areas are available for both versions.

Hardness tables are used to evaluate the hardness value when using the analog unit.

The PC version uses the testXpert^® software. As well as being simple to operate, testXpert^® adapts to varying test conditions with great flexibility. The indentation is measured on the monitor by adjusting the graticules (manually or automatically) and is then evaluated automatically. A master test program for series measurement for Vickers, Knoop and Brinell hardness testing is available and , with add-ons for hardness sequence tests and automatic indentation

measurement. A wide range of further accessories is available in addition to manual compound tables.

Fig. 2: Zwick/ZHV30 manual low-load Vickers hardness tester

Zwick ZHV30 low-load Vickers hardness tester

The Zwick ZHV30 manual low-load Vickers hardness tester covers Vickers (HV) applications EN ISO 6507 and ASTM E 92. With a load range of 0.2 to 30 kg, it can also optionally be equipped for K noop (HK): EN ISO 4545, ASTM E 384 and Brinell (HB): EN ISO 6506 ASTM E 10 also.

As with the Zwick micro Vickers hardness testers, measuring on the Zwick/ZHV30 is performed manually by the operator, using a microscope. One-button control of lens/indentor change is made possible by the automatic turret, while operator influence during hold time is eliminated by a fully automatic test sequence to a specified timeframe. A CCD camera can be retrofitted to the ZHV30 to enable optical evaluation via a PC system.

Optical measurement of the indentation is then performed either manually or automatically with testXpert^® .

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Fig.1: Zwick/ZHV20/Z2.5 Vickers hardness testing machine with motorized compound table, linked to testXpert^®, with automatic indentation measurement

Zwick ZHV20/Z2.5 Vickers hardness testing machine

The ZHV/zwicki-Line Vickers hardness testing machine is the result of integrating the Zwick hardness testing device used for optical methods with a testing machine from the zwicki -Line range. The integrated load cell permits electro-mechanically applied test loads in closed loop mode between 2 and 200 N (ZHV20/Z2.5) and 3 and 300 N (ZHV30/Z2.5). A high-resolution CCD camera is attached to a microscope angled at 90°. Indentor carrier(s) and lenses are integrated in the turret; rotating it brings them into the correct position to make or measure the indentation respectively. The turret has four carriers in total, allowing various different lenses to be used with one indentor.

A testXpert^® master test program contains series tests for the Vickers, Knoop und Brinell methods. Optional add-ons are available for automatic indentation

measurement and focusing and for hardness sequence tests (including multiple sequences), as are manual or motorized compound tables.

Principal features:

• flexible adaptation to test parameters , e.g. approach and test speeds

• manual/automatic indentation measurement

• selectable 5% diagonal monitoring

• selectable pre-check of sequence position

• selectable automatic focusing on any indentation

• freely definable im/exportable sequence tests suitable for all methods

Fig. 2: Zwick/ZHV30/Z2.5 Vickers hardness testing machine with motorized compound table

ZHV20/Z2.5: optional accessories Lens carrier for indentor

Lenses (50x, 100x, 200x, 400x, 600x)

Indentors: • diamond pyramid 136° (Vickers)

• diamond pyramid 172° (Knoop)

• HM ball (Ø 1 mm, Ø 2 mm) Adapter plate for compound table

Compound table: • manual

• manual & digital display &

RS 232 interface

• motorized control Hardness comparison block

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This range of hardness testing instruments features modular design, with a wide variety of equipment, allowing the ideal combination to be produced for each application.

A special feature of our Rockwell hardness testers is an indentor carrier for testing difficult-to-access measuring positions, with straight forward operation thanks to:

• automatic test cycle

• automatic loading and unloading

• automatic evaluation, including conversion

• loading weight selection using rotary knob or via touchscreen (automatic load changing).

These testers are of rugged construction, with a playfree, ball-bearing spindle, test area up to 292 mm in height for large workpieces and an integ rated RS 232 interface for connection to testXpert^®.

Zwick can even provide a standardized solution – using the Zwick/ZHR tester – for the Jominy end quench test (Rockwell sequence testing).

Fig. 2: Zwick/ZHR 8150SK for series testing small batches

Zwick/ZHR Rockwell hardness testing machine

The Zwick/ZHR Rockwell hardness testing range caters for the following methods:

• classical Rockwell methods: Zwick/ZHR 4150 (pre-load:10 kg; test load: 60; 100; 150 kg), Scales A B C D E F G H K L M P R S V;

• super Rockwell method: Zwick/ZHR 4045 (pre-load:

3 kg; test load: 15, 30, 45 kg), Scales N T W X Y

• combined Rockwell and super R ockwell method:

Zwick/ZHR 8150 ( pre-load: 3, 10 kg; test load: 15, 30, 45, 60, 100, 150 kg), Scales A B C D E F G H K L M P R S V N T W X Y

• Jominy method for sequence testing to Rockwell.

The instruments are available with various levels of operating convenience:

• models with one-button operation for simple testing situations (Type AK, Type BK)

• models with line-display and integrated conversion functions for standard applications (Type LK)

• models with Touchscreen, expanded functions and high level of operating convenience for wide-ranging test situations. Used for batch-testing (Type SK) and production control (Type TK).

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Zwick portable hardness testers

Increasing interest is being shown in portable hardness testers, which are used in various ways. Stationary hardness testers in the laboratory are not suitable for large or non-transportable components and plants.

Zwick has a comprehensive range of portable hard - ness testing products for the most varied applications.

Zwick MIC10 hardness tester (UCI method) The Zwick MIC 10 provides quick, handy, on-the-spot hardness testing in conformity with the UCI method (Ultrasonic Contact Impedance, standardized to ASTM A 1038). In what is known as the comparative method, the indentation made by the diamond in the surface of the material is measured electronically and hardness value is immediately shown on the display.

Test probes for loads between 1 N (HV 0.1) and 98 N (HV 10) are available for the portable tester. The automatic conversion function allows results to be expressed in various hardness scales or converted to tensile strength. A ready-integrated statistics function enables individual values or average values to be shown within a series of tests.

The handy Zwick MIC 10 can be used almost anywhere – on scaffolding for testing large containers and pipes, or for component testing wherever it is needed. The UCI method is particularly suited to testing hardened surfaces and fine-grained materials of various shapes and sizes.

Thanks to the small, slender probe, measurements can be made in hard-to-reach locations.

Zwick DynaPocket –

digital rebound hardness tester

The Zwick DynaPocket is an extremely handy integrated digital hardness-testing instrument which uses the dynamic rebound hardness method (Leeb) (standardized to A956). Its compact design allows easy on-the-spot testing of bulky, non-transportable components such as forgings or castings, even at locations which would be difficult for other testers to reach. Fast, reproducible measurements can be obtained regardless of impact direction thanks to patented signal processing

technology. Operation is straight forward via 2 buttons, with settings and hardness values shown on a digital LCD display.

Fig. 1: Zwick MIC 10 portable hardness tester Fig. 3: Zwick DynaPocket rebound hardness tester with patented impact direction

The tester already contains standard conversion tables for nine materials groups, enabling conversion of

hardness values for hardness scales HV, HB, HRC, HRB, HS, HL und N/mm². It is therefore extremely well-suited to material identification in such locations as goods inwards or a raw materials store.

Fig. 2: DynaPocket digital rebound hardness tester plus accessories

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Zwick Sclerograph – mechanical rebound hardness tester

The portable Sclerograph is based on the dynamic rebound height method. This analog device can be used to determine the hardness of steel, non- ferrous metals and rubber. The rebound height is read off and the hardness value is taken from the comparison chart supplied with the instrument. This contains Shore D, Rockwell B and C plus Brinell hardness.

Fig. 1: The portable Zwick Sclerograph

Zwick Webster hardness testing pliers Portable, easy-to-use pliers with built-in indentor and spring. Squeezing the grips together presses the indentor (via the spring) into the material to be tested (thickness 0.6 mm ... 8 mm) and the indentation depth is shown on the scale. The value is read off and converted to

Rockwell hardness using the chart supplied. These testing pliers are used for aluminium, aluminium alloys, brass, copper alloys and steel in the following range:

Rockwell E20 to E110 (max.).

Zwick PZ3 Brinell testing clamp

This unique portable hardness tester is suitable for standardized static Brinell ball indentation tests up to 29420 N (3000 kg). Hardness tests can be performed on materials and workpieces unsuitable for testing in the laboratory. Examples include stored steel stocks, finished structures, machines and larger metal components.

Fig. 3: Zwick PZ3 Brinell clamp for tests up to 3t

Zwick Barcol hardness tester

This digital hardness tester is especially suitable for testing flat or lightly curved specimens, including fibreglass-reinforced plastics, duroplasts, hard thermoplasts, finished and semi-finished goods and aluminium, to EN 59 and ASTM D2583.

Hardness testing with Zwick