Introduction to
Metallurgy
An Interactive Video Teletraining Course
Developed and Presented by
Terry Khaled
National Resource Specialist
Metallurgy
Federal Aviation Administration
Table of Contents
GETTING
STARTED
How Do I Use This IVT Guide? . . .
I.
AIRFRAME
ENGINEERING
CURRICULUM
What Does the Curriculum Cover? . . . ..*...*...
Two-Week Job Function Course .,.,...*...*...
Overviews of Technical Subjects . . .
Core Technical Subjects Courses ,...**
II.
IVT COURSE ORIENTATION
About This IVT Course . . . ..*...*...
What Is IVT? . . .
Who Is the Target Audience? . . . .._...--...
Who Is the Instructor?
. . . ..*...
What Will You Learn? .**...*...*..*...
How Will This Course Help You On the Job? . . .
What Topics Does the Course Cover? . . .
What Are Some Good References? . . .
III.
SELF-ASSESSMENT
& EXERCISES
Pre- & Post-Course Self-Assessment Questions . . .
APPENDICES
A.
B.
C.
Metallurgy IVT Presentation Visuals
Aircraft Alloys
B-l.
Aluminum Alloys
,
B-2. Titanium Alloys
B-3. Carbon, Low Alloy, and Alloy Steels
B-4. Corrosion Resistant (CRES) Steels
B-5. Superallbys
Self-Study Video Course Evaluation Form
1
6
6
7
7
8
8
8
10
11
Instructional Video Teletraining Course
Federal Aviation Administration
April, 1998
Introduction to Metallurgy
i
Getting Started
How Do I Use
This IVT guide provides you with the position of this course in
This IVT
the Airframe Engineering Curriculum, an orientation to the IVT
Guide?
course, support materials for use during the broadcast, self-
assessment and practice exercises, and the course evaluation.
Follow these steps to complete your study.
1. Read Section I, Airframe Engineering Curriculum,
to
familiarize yourself with the the overall scope and format of
the curriculum.
2. Review Section II, IVT Course Orientation, before the
broadcast, if possible, to get an overview of the purpose of
the course, the target audience, the instructor, what you will
learn, how this course will help you on the job, the topics
covered in the course, and some good references on the topic.
3. Answer the pre-course self-assessment questions in Section
III, Self-Assessment .
4. Turn to Appendix A, Metallurgy IVT Presentation Visuals,
and refer to it during the broadcast. Appendix A contains the
visual support material used by the instructor during the
broadcast. You can use these visuals to take notes and follow
along with the broadcast presentation.
5. Refer to Appendix B, Aircraft Alloys, for additional
information, including designation systems and chemical
composition listings.
6. Complete the post-course self-assessment in Section III, Self
Assessment.
7. Complete the IVT Course Evaluation Form in Appendix C
and send it to your Directorate/Division
Training Manager
(ATM).
Airframe Engineering Curriculum
I.
Airframe Engineering Curriculum
What Does the
,The Airframe Engineering Curriculum fits into the broader AIR
Curriculum
Training Program that is summarized in the following figure.
Cover?
An Overview
ASE Airframe Job Function o Z-week Course I o Technical Topics-IVTNideo / 0 Follow-an Co”r~n I / ASI : JabFunction j ASE Systems : Job Function ) ME / 1 Propulsion I Job Function Flight Test I Job FuncdonFirst
Year with
Aircraft
Certi~c~n--~z-
_---
*-
-.---
i DACT.OAT I 1I
Continuing
Development
Within the context of the AIR Training Program, the Airframe
Engineering Curriculum is designed to effectively meet the
critical safety mission of the FAA by addressing the following
Service goals:
Standardization
l
Promote standardization throughout the organization in task
accomplishment and application of airworthiness
regulations in order to achieve uniform compliance.
Instructional Video Teletraining Course
Federal Aviation Administration
April, 1998
Introduction to Metallurgy
2
Airframe Engineering Curriculum
,Job Performance Proficienw
l
Reduce significantly the time required for newly-hired
engineers to attain full job performance proficiency.
Customer Service
ll
Establish and maintain appropriate, effective, and
responsive communication, collaboration, leadership, and
teamwork with both internal and external customers.
In addition to the Service goals, the Airframe Engineering
Curriculum is designed to provide ASEs with job function
training in three domains:
l
Tasks and procedures governing the work of engineers in
design approval, technical project management, certificate
management, and designee management.
l
FAR airworthiness requirements that are the purview of
airframe engineers. Generally they are subparts C and D of
FAR Parts 23,25,27, and 29.
l
Technical subjects essential for all new engineers to meet
both introductory requirements and, later, minimum
technical proficiency level requirements.
The resulting Airframe Engineering Curriculum structure
consists of three main types of training opportunities -
1. Two-Week Job Function Course
2. Overviews of Technical Subjects
3. Follow-on Core Technical Subjects Courses
Two-Week Job
The Two-Week Job Function Course uses an instructor-led,
Function
classroom-based format with lecture, discussion, and individual
Course
and group activities. Supporting materials used in the course
include print, overhead transparencies, videotapes, job aids,
and documents and sample reports.
Airframe Engineering Curriculum
The course is divided into the following two major sections:
Week I
l
Certification
Tasks - includes design approval, technical
pr6ject management, certification management, and DER
management.
Week 2
l
FAR Requirements
and Key FAR Sections - includes
training in the subparts of the FAR that apply to airframe
engineers (subparts C and D) at two levels: an overview of
those subparts across FARs 23,25,27, and 29; and in-depth
discussion of significant sections of the FAR that are
important to the Service. The importance of these sections
may stem from problems in interpretation and application of
requirements, technical complexity of a design, “high
visibility”
projects, or safety considerations that are
paramount.
Overviews of
Technical
Subjects
High-level overviews of ten technical subjects are presented by
NRSs or other senior engineers. These overviews are available
in two modes:
l
An initial live three to four hour IVT satellite broadcast with
accompanying course material is received at each
Directorate and other downlink sites.
l
A Video/Self-Study Training Package adapted from the
initial IVT presentation and accompanying course material
is available through the Directorate Training Manager.
Basic concepts and FAA-specific applications and examples
are provided for each of the following ten technical subjects:
l
Aircraft Loads
l
Fatigue/Fracture Mechanics/Damage Tolerance
l
Composite Materials (Design/Certification
Considerations
in Composite Aircraft Structure)
Instructional Video Teletraining Course
Federal Aviation Administration
April, 1998
Introduction to Metallurgy
4
Airframe Engineering Curriculum
l
Crashworthiness/Occupant
Protection
l
Material Properties/Manufacturing
Processes of Metal
(Introduction to Metallurgy)
l
Stress Analysis
l
FluttexYAeroelastic Stability
l
Structural Test Methods
l
Design and Construction
l
Repairs and Modifications
Each technical subject overview is designed to not only
provide ASEs with the FAA perspective on the topic, but also
serve as an indicator of what further training may be needed.
Core Technical
As a follow-on to the Overviews of Technical Subjects, the
Subjects
curriculum will provide more in-depth training on the
Courses
following three subject areas:
l
Basic Loads
l
Stress Analysis and Structural Test Methods,
l
Repairs and Modifications
These core technical subjects are essential to the technical work
of the airframe engineer in a regulatory environment regardless
of product or technology. Training in each of the core subjects
will be designed to bring airframe engineers to a minimum
level of technical proficiency and to help promote proficiency
in the application of the technical knowledge in an office work
environment.
Additional technical training for engineers beyond these core
subjects will depend largely on AC0 organizational needs
stemming from customer requirements, products certified,
emerging technology, and the number of staff requiring more
IVT Course Orientation
II.
IVT Course Orientation
About This
IVT Course
Introduction to Metallurgy
is one in a series of ten “Overviews
of Technical Topics” in the Airframe Engineering Curriculum
designed to prepare you to effectively meet the critical safety
mission of the FAA. [For more information oy2 the Airframe
Curriculum, rejer back to Section I
of
this guide. J
Through a five-hour Interactive Video Teletraining (IVT)
format, Terry Khaled, the FAA’s National Resource Specialist
for Metallurgy, will provide you with the basic concepts of
metallurgy, including information on solidification and
solidification structures and fabrication methods and their
effects, and, woven throughout the course, key points to look
for or be aware of in a certification project, including knowing
when to call in a metal specialist.
What Is IVT?
Interactive Video Teletraining, or IVT, is instruction delivered
using some form of live, interactive television. For the
overview courses, the instructor delivers the course from the
television studio at the FAA Academy in Oklahoma City.
Through the IVT broadcast facility instructors are able to use a
variety of visuals, objects, and media formats to support the
instruction.
Participants are located at various receive sites around the
country and can see the instructor and his/her materials on
television sets in their classrooms. The participants can
communicate with the instructor either through a microphone
and/or the simple-to-use Viewer Response System keypads.
During the live presentation, when a participant has a question
or the instructor asks for specific participant responses to
questions, the participant(s) can signal to the instructor using
their keypad. The collective participant responses or the name
Instructional Video Teletraining Course
Federal Aviation Administration
April, 1998
Introduction to Metallurgy
6
IVT Course Orientation
Who Is the
Target
Audience?
Who Is the
Instructor?
Terry Khaled
of a specific participant signalling a question are immediately
visible to the instructor on the console at the broadcast site.
The instructor can then respond as needed. When the instructor
calls on a specific participant to speak from a site, participants
at each of the other sites can simultaneously hear the
participant who is speaking.
This course is designed for:
l
New and experienced FAA airframe engineers who are not
proficient or expert in metallurgy but who require enough
knowledge of the subject to be able to review data
submitted by manufacturers.
l
Inspectors who enforce inspection procedures resulting
from the engineering evaluation required to satisfy FAR
25.571.
Dr. Tarek (Terry) Khaled, has more than 25 years of
experience in metallurgical engineering, mechanical design,
manufacturing, and project management. He has worked at
five aircraft manufacturing companies, coming to the FAA
from Rockwell International, Space Systems Division. His
latest experience in airframe materials was gained through
work on the space shuttle, the F- 18, and the F-l 11. Dr. Khaled
also has experience with the heat resistant alloys that are used
in turbine engines, which was gained by working on fighter
engines and aircraft power systems. Terry enjoys reading
about military history, hardware, tactics, and strategy. He also
loves middle eastern foods.
IVT Course Orientation
What Wili You
After completing this course you will have a basic
Learn?
understanding of the concepts and principles of metallurgy,
including:
l
The nature of metals.
l
Solidification and ingot structures.
l
Deformation and mechanical working.
l
Strengthening mechanisms.
l
Effects of fabrication and finishing operations on properties.
How Will This
After completing this course, you should be able to:
Course Help
You On the
Job?
l
Describe how metals and alloys solidify and list the factors
that control ingot structure.
l
Understand how mill products are produced from ingots by
hot and cold working, and be able to distinguish cold from
hot working.
l
Describe how metallic materials are hardened by heat
treatment and by other means.
l
Understand how fabrication and finishing operations affect
the properties of metals and alloys.
l
Recognize when, for certification purposes, a metallurgist
needs to be part of the FAA team.
What Topics
The following topic outline is intended to give you an overview
Does the
of the course content. In addition to this outline, Appendix A
Course Cover?
contains the visual presentation material and supporting text
for each figure used by the instructor during the broadcast.
I.
Introduction
II.
The nature of metals
1.
Atomic and crystal structures
2.
Polymorphism
Instructional Video Teletraining Course
Federal Aviation Administration
April, 1998
Introduction to Metallurgy
8
IVT Course Orientation
III.
Solidification
and solidification structures
1.
Pure metals
2.
Alloys
3.
Phase diagrams
4.
Cast/ingot microstructure control
IV. Fabrication methods - overview
1.
Mill products and mechanical working
2.
Deformation
a.
Single crystal
b.
Polycrystalline metals
C.
Effects of temperature
d.
Cold and hot working
e.
Primary and secondary working
3.
Strengthening in metals
a.
Dispersion hardening
b.
Strain hardening
C.
Grain size
d.
Solid solution strengthening
e.
Second phase hardening
f.
Hardening heat treatments
V.
Effects of fabrication operations
VI. Effects of finishing operations
IVT
Course Orientation
What Are
Some Good
References?
There are many references related to metallurgy, too numerous
to mention here. However, the following references contain
many other references on these subjects and will, help to guide
you in the right direction.
Avner, Sydney, H. Introduction to Physical Metallurgy.
McGraw-Hill,
1964.
Guy, A.G. Physical A4etallurgy for Engineers. Addison-
Wesley Pub. Co., 1963.
Smith, M.C. Principles of Physical Metallurgy.
Harper &
Brothers Pub., 1956.
Burton, M. S. Applied Metallurgy for Engineers. McGraw-
Hill, 1956.
Keyser, C.A. Materials Science and Engineering, 2nd Ed.
Charles E. Merrill Pub. Co., 1974.
Flinn, R.A. & Trojan, PK. Engineering Materials and Their
Applications.
Houghton Mifflin Co., 1975.
Doyle, LE. Manufacturing Processes and Materials for
Engineers. Prentice-Hall, Inc., 1985.
United States Steel. The Making, Shaping, and Treating of
Steel, IOth Ed. 1985.
The Metals Handbook Series. American Society for Materials
(20 volumes).
Instructional Video Teletraining Course
Federal Aviation Administration
April, 1998
Introduction to Metallurgy
10
Self-Assessment
IV. Self-Assessment
Pre- & Post-
Course Self-
Assessment
Questions
The instructor will ask you at the begining and end of the
presentation to respond to the following four questions about
metallurgy as it impacts the certification process.
Rate your confidence level for each of the following statements
before and after completing the course.
1. Rate your level of understanding about the facotrs that
control ingot structure and properties.
Very
Moderately
Not
Confident
Confident
Confident
BEFORE
THE COURSE:
0
0
III
AFTER
THE COURSE:
cl
cl
cl
2. Rate your level of understanding of the effects of
mechanical working on microstructure and properties.
Very
Moderately
Not
Confident
Confident
Confident
BEFORE
THE COURSE:
Cl
cl
III
AFTER
THE COURSE:
q
I7
cl
3, Rate your understanding of how hardening by heat
treatment impacts microstructure and properties.
Very
Moderately
Not
Confident
Confident
Confident
BEFORE
THE COURSE:
0
cl
El
AFTER THE COURSE:
0
q
Cl
Self-Assessment
4. Rate your understanding of how fabrication and finishing
operations can affect the microstructure and properties.
Very
Moderately
Not
Confident
Confident
Confident
BEFORE
THE COURSE:
El
0
cl
AFTER
THE COURSE:
0
cl
cl
Instructional
Video Teletraining
Course
Federal
Aviation Administration
April, 1998
introduction to Metallurgy
I2
Appendix A
Appendix A
Introduction
to Metallurgy
IVT Presentation Visuals
INTRODUCTION
TO
METALLURGY
By: Terry Khaled, Ph.D.,
NRS-Metallurgy
l
Certification
efforts require knowledge
of type design
l
Type design
+ Form, fit, and function
4 Materials
and processes
- Material type and condition/heat
treatment
- Surface finishing
(coatings,
shot peening)
- Inspection
and test
I. Materials
and processes
integral to type
design
2
IVT Course
Federal Aviation Authority
April, 1998
Introduction to Metallurgy
A- I
cc
After completing
this course, you should
be able to:
lDescribe how metals and alloys solidify and list the
factors that control ingot structure.
. Understand
how mill products are produced from
ingots by hot and cold working, and be able to
distinguish
cold from hot working.
. Describe how metallic materials are hardened by heat
treatment and by other means.
. Understand
how fabrication
and finishing
operations
affect the properties of metals and alloys.
. Recognize when, for certification
purposes, a
metallurgist
needs to be part of the FAA team.
3
Materials -
. Metals
Organic (polymers/plastics,
wood)
Non-
-metals
I
r
Ceramic (Al,03, SiO,)
c Inorganic
Non-ceramic
(C, B,
water, graphite, CaO)
r Metal-Ceramic
Composite
+-I
Organic-Ceramic
.
LOther (Carbon-Carbon)
Note:
Elemental
semiconductors
(Si, Ge) fall under
metals.
l
Science,of,converting
rocks into
metals and alloys such as those used
on aircraft, autos, & other prqducts.
i Branches
- Extractive
- Ingot
- Powder.
- Physical
,
,
6
IVT Course
Federal
Aviation
Authority
April,
1998
introduction
to Metallurgy
. Extraction
of metals from ores
+ Mining
+ Ore dressing
- Crushing
- Grinding
- Concentration
l
Extraction.
- Heat (Fe, Ni)
- Leaching
(Ti, Co, Cu)
- Electrochemical
(Al)
7
. Production
of metal and alloy ingots
+ From extracted
metals, scrap, or both
- Refining:
Remove undesirable
elements
- Alloying:
Obtain desired alloys
. Use of powder techniques
to produce
+ Near-net shapes
+ Wrought
powder metallurgy
products
(standard
shapes for further processing)
9
l
Production
of finished
parts from ingots
or powder products
l
Mechanical
working:
Rolling, extrudi
forging,
drawing
l
Heat treatment
%I9
l
Fabrication:
Casting, welding,
brazing,
forming,
coating, etc.
10
1VT Course
Federal Aviation Authority
April, 1998
introduction
to Metallurgy
A- 5
. Focus on three important
pillars of
metallurgy
+ Solidification
and ingot structures
l
Mechanical
working
l
Hardening
by heat treatment
and other
methods
11
. The Nature of Metals
. Solidification
& Solidification
Structures
l
Fabrication
Methods
l
Mill Products
& Mechanical
Working
. Strengthening
in Metals
l
Effects of Fabrication
Operations
. Effects of Finishing
Operations
l
Distinctive
luster
l
Malleable,
ductile
+ Exceptions:
Na brittle, Hg liquid, etc.
l
Good thermal & electrical
conductivity
+ Some non-metals
also
l
Form positive
ions
0 Crystalline
l
Inorganic
materials
also
13
Abmic
B
c~stan
smctums
BCC
FCC
@J$gg
l
Atomic
Structure-metallic
bond
+ Positive “ions” surrounded
by electron cloud
0 Crystal Structure
+ 14 basic types (metals or non-metals)
+ Most engineering metals
-Body
centered
cubic
(KC)
- Face centered
cubic
(FCC)
-Close-packed
hexagonal
(CPH)
+ Other types include (tetragonal, orthorhombic)
14
IVT Course
Federal Aviation Authority
April, I998
Introduction to Metallurgy
A- 7
. Metal has different
crystal structures
l
Depending
on temperature
. Iron (Fe)
+ BCC at elevated temperatures
l
FCC at intermediate
temperatures
l
BCC at the lower temperatures
l
Titanium
(Ti)
+ BCC at elevated temperatures
+ CPH at the lower temperatures
15
. Metals exist in three states
+ Vapor
+ Liquid
+ Solid
. Solidification:
Liquid-
solid
+ Also known as crystallization
- Liquid:
No crystal structure
- Solid:
Crystal structure
.
Most metal and alloy tonnage
produced
as ingots
l
Ingot production
involves melting
and solidification
l
Casting is a common
near-net shape
production
method
+ Casting production
involves melting
and solidification
I. It is important to understand
solidification
processes
for pure metals and alloys
17
Topics covered:
l
Pure Metals
l
Alloys
l
Phase diagrams
. Cast/ingot
microstructure
control
18
IVT Course
Introduction
to Metallurgy
. Slow uniform
cooling
l
Crystallization
at one
temperature
-Arrest
line
. Crystallization
by
,98,0F
nucleation
and
growth
+ Solid
crystals
resemble
trees
-Called
dendrites
. Dendrites
eventually
touch-no
more liquid
o
l
Each dendrite
called
grain
l
Fully solidified
microstructure
+ Single phase
.- Only one pure metal
l
Polycrystalline
structure
- More than one grain
- Grains separated
by
grain boundaries
. Alloys made
+ Unintentionally
- Undesirable
impurities
+ Intentionally
-To obtain desirable
properties
l
An alloy
consists
of more than one
component
l
Component:
Metal, non-metal,
or stable
compound
+ At least one component
must be metal
21
. Alloy system
+ All compositions
that can be made
from components
l
Alloy system can be
+ Binary (2 component)
system
+ Ternary (3 component)
system
+ Quaternary
(4 component)
system
+ Higher systems
- No specific
names assigned
22
IVT Course
Federal Aviation Authority
April, 1998
Introduction to Metallurgy
A- I I
. An alloy consists
of one or more phases
l
Phase: Uniform,
homogeneous
substance
-
can be separated
mechanically
. At elevated
temperatures
+ Liquid phase:
Amorphous
(no crystal structure)
l
At lower temperatures
+ Solid phase(s):
Crystalline
l
Number
and type of phases present depend on
+ Composition,
number of components,
temperature
23
l
Solid solution
l
Interstitial
-Solute
atoms
(small)
between
solvent
atoms
+ Substitutional
-Solute
atoms
in
solvent
sites
l
Compound:
chemical
formula
l
Metal/Non-metal
(e.g., Fe&)
4 Metal/Metal
(e.g.,
N&AI)
Interstitial
0
Solvent
atoms
l
o
!zfP
l
0
Solute
l
l
be
atoms
fin
?%a3
Substitutional
24
. Summary sheets describing
+ Cdoling charakteristics
l
Phases present
l
Exist for
+ Binary and higher alloy systems
- Binary
systems
n
Basis for higher
systems
m Easier
to work with
I
25
I
IVT Course
Federal
Aviation
Authority
April,
1998
introduction
to Metallurgy
Binary Phase
Diagmms
constructkm
. From cooling curves
. Pure metal solidification
. One curve per composition
lConstant
temperature
+ Arrest line
l
Alloy solidification
lTemperature
range
100
80 60 40 20 O+%A
lNo arrest line
ljf!\!!f\\J
im
ki;@&
i
Time
A
Composition
B
COOLING
CURVES
PHASE DIAGRAM
26
Binary Phase Diagmms
cootiinat@s
lAbscissa:
Composition
(weight or atomic %)
. Ordinate:
Temperature
(OF or OC)
Liquid
+ Solid
A
Composition
B
27
l
Determine composition
of
phases at any temperature
(T): e.g., 80% A-20% B alloy
7’
l
Construct
tie line mo at T
- m: Composition
of solid
- o: Composition
of liquid
t
E!
. Determine relative amounts
i
i a j
i
of phases at
T
E
;*
f
;
+ Construct
tie line at T
8
+ Use lever rule (next slide)
A 100
9b
I
l
Predict microstructure
00
74 70
0
10
20
26 30 B
Composition
28
m
n
*
0
h
10 units
A
6 unitsA
/I\
Fulcrum
/I
\
Wt of liquid
Wt of solid
phase
phase
Amount
of liquid
: Amount
of a
m
ni
90%A
10
;
6
o Ii uid
Liquid (%) = E
x 100
a---
74%ii
a("h)=~oxlOO
60%A
Liquid (%)
=Lox100=62.5%
,6
a (%)=,i
x 100 = 37.5%
29
IVT Course
Federal
Aviation Authority
April, 1998
Introduction
to Metallurgy
A-15
systems
+ Unlimited
solid
solubility
- All alloys exist as
one solid phase
. Example:
Cu-Ni
system
(next slide)
l
Slow uniform
cooling:
50% Cu, 50% Ni alloy
2800
2600
F
d 2400
L
g 2200
b
I+
F
2000
1800
Rm
Temp.
ICUI
% Nick&l
Ni
- Solidification
by dendrite
nucleation
& growth
Nuclei (67%Ni, 33% Cu)
formed in liquid
(about 50% Ni, 50% Cu)
Dendrites (60% Ni,
40% Cu) growing
to
liquid (43% Ni, 57Th Cu)
0'
lime
+
l
Fully solidified
microstructure
in previous example
+ Single phase
- Cu-Ni solid
solution
l
Polycrystalline
structure
-More
than one grain
-Grains
separated
by grain
boundaries
+ Looks same as pu’re metal?
. - Not really
32
IVT Course
Federal Aviation Authority
Introduction to Metallurgy
April, 1998
A-17
l
Dendrites form over
temperature
range
+ Composition
of
solid
varies
with
temperature
- Richer in Cu
at lower
temperatures
(Compare
cq,
a2 and as)
2700 -
loo0
232937
77 71 63 50
50
75
25
100% cu
0% Ni
33
l
Dendrites
are not chemically
homogeneous
+ True for all alloy systems
+ Distinct
look
under
microscope
l
Inhomogeneity
eliminated
by
+ Homogenization
anneal
or mechanical
working
Dark areas:
Ni-rich
SdidSo~~ooa
Ai%~ySystems
CompMmon & Pmpem*es
l
Properties
vary with composition
+ True for all alloy systems
l
Alloy properties
differ from pure metals
l
Property maxima or minima
+ Reached at different
compositions
35
ectrical resisti
IVT Course
Federal Aviation Authority
April, 1998
Introduction to Metallurgy
A-19
a
Liquid phase -2
solid phases (L-
a +p )
+ At constant
temperature
(t&
-Called
eutectic temperature
(lowest melting temp.)
-Arrest
line on cooling curve
0
Metals A and B: Limited
mutual solid solabilities
. Changes
in slope of cooling
curve
+ At beginning
2%
end of transformations
37
90%A+
lo%19
60%A+4O%B
Time
+
0 10 20 30 40 50 6070
8090100
% metal
B -w
. Properties
vary with
composition
+ True for all alloy systems
-e.g., solid solution alloys
6 Alloy properties
different
from pure metals
% component
B
39
Eutctic mixture
Microstructure
vs Temperature
for Alloys 1,2,3, and 4
[a or p formng before eutectic referred to as primary a or
Bl
40
IVT Course
Federal Aviation Authority
April, I998
Introduction’to
Metallurgy
A-21
Microstructures
Interfaces
,
l
Grain boundaries
l
Separate grains of
same phase
l
Phase boundaries
+ Separate different
phases
l
Cell boundaries
l
Separate colonies
(cells)
-e.g., cells of eutectic
mixture
Interfaces
Atomic Structure
,
. Interfaces
provide
transition
+ From one orientation
I
to other
Grain -
-Grains
of same
phas
- Grain boundaries
+ From one crystal
structure to another
-Phase
boundaries
+ Between colonies of
different orientation
e
Grain
-Cell boundaries
42
--.
-_
I
0 Potential sites for
+ Precipitation
+ Phase transformation
l
Impurity
segregation
+ Cracking
43
lConstructed
from
cooling curves
. Involves
several
phases
+ 6, a Ferrite
(BCC)
+ 6: Austenitk
(FCC)
+
Fe&:
Cementite
- Orthorhombic
(right
angles, a#b#c)
. Covers steels &
cast
iron
+ Steels: C C 2%
l
Cast Irons: C X2%
IVT Course
Federal Aviation Authority
April, 1998
Introduction to Metallurgy
A-23
. Complexity
of phase
Diagram
2800
Aquid
_____________
*Due to 3 Allotropic
forms
(phases)
of Fe
t-7
2554 -
Gff?B,c&:
___.
Y Fe F.C.C.
- 6, Y, a
. Cooling
curve
+3 arrest
lines
. Nucleation
+6 : from
melt
l
y : on 6 grain
boundaries
nonmagnetic
_____-_---.--.
i,
a Fe B.C.C.
*a : on y grain
boundaries
Time -
45
Eutectic
at 2065OF
28OC
+ Liquid
c-g
&+
+Fe,C
2:;
Eutectic Mixture
+ Eutectic
Mixture
- Should
consist of 1666
alternate
y and
Fe& plates
- Usually:
rounded
y
”
areas in Fe,C matrix
g
+ Arrest
line on
t;i
cooling
curve
&I
E
l
Same solidification
$
principles
as before
h ?Eutectoid
925% F
I
1 f%; ii i i 1
I 0.8
z
3
4.3 5
li.87
#Steels&
Cast irons
‘37
l
Arrest
line on
a;
Y
@25%
t
cooling
curve
+ Basis
heat treatment
for steel
:
I[
0 0.8
1
f;e3;
2
3
ii
4.3 5
i
i
1
IVT Course
Federal Aviation Authority
April, 1998
Introduction to Metallurgy
A-25
Representation
of crystal growth from uniformly
cooled
melt. Crystals begin to form at random locations in melt
and grow uniformly
until restricted
by neighbors
or walls
of container.
a.
Crystals
beginning to form.
b. Unrestricted
spherical growth.
c. Metal completely
solid, with shape of each grain determined
by
interference
with other grains and walls of container.
48
l
Nucleation
l
Multiple
random sites
+ Equiaxed
grains
. Faster (but uniform) cooling
+ More nucleation
sites (thermodynamics)
+ Finer grain structure
- Finer grain and cell sizes
l
Seeding
=b
finer grain structures
l
Finer grain structures
better
mechanical
properties
Progressive
formation
of columnar dendrites.
Freezing
begins at wall of the crucible.
Restriction
of sidewise
growth and the temperature
gradient from outside to center
of the melt encourage
formation
of columnar grain shape.
a. Freezing
beginning
at container
walls.
b. Freezing
continuing.
c. Freezing
complete.
Shrinkage
cavity is formed
at center
of solid metal.
50
,
l
Nonuniform
cooling
temperature
gradients
l
Mold walls cool faster
l
Nucleation
at mold walls
l
Growth parallel to gradient
-Columnar
dendrites
l
Basis for
+ Directional
solidification
(DS) :
l
Growing
single crystals
(SX)
.,.,..
. DS & SX used in jet engines
Columnar
Gralns in
a lead casting
51
IVT Course
Federal
Aviation Authority
April, 1998
Introduction to Metallurgy
A-27
Typical Ingot Structure
Steel
. Three microstructural
zones
+ Fine equiaxed grains (4)
3
-Fast uniform cooling at
mold surfaces
+ Columnar grains (5)
- Growth under temperature
gradient
4 Coarse equiaxed grains (6)
-Slow
uniform cooling
l
Casting defects
l
Pipe (I),
cavities (Z), &
porosity (3)
Fabrication
Methods
Topics covered:
0 Overview
l
Mill products and mechanical working
. Importance of mechanical working
L
c
l
Metallic components
fabricated
+ By near net shape methods
-Casting
-Powder
metallurgy
+ From mill products
-Machining,
forming,
welding,
brazing,
forging,
adhesive
bonding,
etc.
l
Mill products
+ Bars, rods, plate, sheet, tube, wire, billet,
and shapes
54
l
Mill products
produced
+ By mechanical
working
of’
- Ingots
- Wrought
powder
products
l
Mechanical
working
+ Deformation
at ambient or elevated
temperatures
- Rolling,
extruding,
forging,
drawing
55
IVT Course
Federal Aviation Authority
April, 1998
Introduction to Metallurgy
A-29
. Produces
the useful shapes we use
. Breaks down coarse ingot dendritic
structure
. Enhances
chemical
uniformity
. Closes porosity
. Improves
mechanical
properties
I
56
Topics covered:
l
Deformation
l
Single crystals
l
Polycrystalline
metals
l
Effects of temperature
+ Stress relief
+ Recrystallization
+ Hot vs cold working
. Primary and secondary
working
l
Study of deformation
essential
to
understand
+ Production
of mill products
+ Properties
of mill products
l
Study of deformation
+ Two steps
-Single
crystals
- Polycrystalline
metals
Debmation
- Singk Crystak
l
Deformation
+ Elastic
l
Plastic
(permanent)
- By slip on slip systems
(4
(b)
(4
(4
Elastic
and Permanent
Deformation
of Metal Loaded
in
Shear.
(a) Original
crystal,
unstressed;
(6) elastic
strain
produced
by load below elastic
limit;
(c) increased
elastic
strain
plus permanent
strain
by slip, resulting
from load
above
elastic
limit;
(o’) load removed;
only permanent
strain
remains.
59
IVT Course
Federal Aviation Authority
April, 1998
Introduction to Metallurgy
A-3 I
. Slip system
l
Close paced direction + close packed plane
4 Closest atomic spacings
:. Strongest
l
Easier to move along than through
FCC
HCP
60
l
Stress resolved along
slip direction
l
Shear component
-
slip
l
Normal component
-
favors fracture
l
F:applied
force, A: cross
sectional
area, T: Resolved
shear stress
l z
=Area of slip plane=
-
F’
A/COS$~~*
’ = A
L
SinX CosX
+2
=OsinX
Cos k
I
l
Slip starts
+ At most favorably
oriented system
-X,h=45°
+ When Tc is reached
- 7,:
critical
resolved
shear stress
l
No slip when ‘c = 0
+ Slip plane or direction
I to tensile axis
(h=90,cosh=0)
l
Slip plane parallel to tensile axis
(2, = 0, sin x. = 0)
62
IVT Course
Federal
Aviation
Authority
April,
1998
Introduction
to Metallurgy
. Specimen
ends forcibly
restrained
l
Slip planes & directions
rotate
-Align
with principal
strain
axis
. Rotation
=W preferred
orientation
. All deformation
processes
l
Involve restrain
.I Rotation & preferred orientation
l
Universal
phenomena
I
63
(a) Initial condition
of the crystal.
The
location
of the
active
primary
slip
plane
is shown.
Direc
of sli
(b) Shear can be
pictured
as occurring
in this manner
on each of the
(c) Since the axis of loading
actually
remains
vertical,
the
angle changes
significantly.
Range of
plastic deformation
n: coef.
of strain
hardening
Extension
65
Yield strength
. Releasing
load in
I:
I:
plastic
range
.-
I:
;;
z
:i
l
Some elastic
recovery
takes
place
+ Some permanent
set
E
.‘/
____-
--_*
-. .
\ ,
.
1 :
a :
ti _ _ _ _
I :
I :
2
i
I I
I :
I
i
I :
; !
remains
to
i
I i
. Generally,
yield point
I :
* :
not well defined
I :
I :
! :
I :
l
Define 0.2% offset
I :
yield strength
v
i
Strain, in/in
0.2% offse
I+
-Plastic*
I L
Elastic strain
(Permanent)
strain
66
IVT Course
Federal
Aviation
Authority
April,
1998
Introduction
to Metallurgy
. Each grain behaves as
single crystal
+ Rotation & preferred
orientation
Before
After
+ Grains become elongated
l
Brittle particles/
Brittle
particle
compounds
l
Do not deform
+ Break & form
broken lines
- Called stringers
67
l
Mechanical working of say
Fe specimen at room
temperature
+ Same effects observed
in
tensile test
- Rotation
& preferred
orientation
- Elongated grains & stringers
l
Each time section is reduced
+ Strength
* , ductility*
z
+ Grains:
more elongated
g
- More difficult to distinguish
l
Stringers:
finer and longer
75% prior reduction
-
of thickness
r
50%
No prior reduction
. Grain Boundaries
+ Obstacles
to deformation
-Slip
changes
direction
from grain to grain
-Force
must
be resolved
- gets smaller
+ Major source of strain hardening
69
Grain
BoQandaties
and
Pmp@mes
. Finer grain sizes
+ Higher
strength
+ lower
ductility
(usually)
l
Example:
Iron alloys
(see graph)
7
III
!
I
!
!
!
!
!
’
0
2
4
6,
8
10
w,
mm
“I,
70
IVT Course
Federal
Aviation
Authority
April,
1998
Introduction
to Metallurgy
. Mechanical
working
of say Fe specimen
at room temperature
+ Continued
reductions*
fracture
. To avoid fracture
+ Must eliminate
effects of prior deformation
- By heat treatment
l
Two heat treatments
0 Stress relief (low temperature)
+ Recrystallization
anneal (higher temperature)
71
. Heating at fairly low temperatures
l
Slow process
+ Elimination
of effects of prior deformation
- Requires
very long times
- Not practical
l
Practical stress relief cycles
,
+ Only eliminate
some residual stresses
6 Ineffective
in elimination
of effects of prior
deformation
l
Heating above recrystallization
temperature
+ New, stress free grains.appear
-By nucleation and growth
+ Initial room temperature
properties
restored
- Further mechanical working possible
. Used between reduction
passes
+ Also called:
Intermediate
anneal
73
Stages of recrystallization.
(a) Stress-free
nuclei appear;
(4
(b) Nuclei grow into new
crystals,
and some
additional
nucleation;
(4
(c) Original
crystals
disappear,
and recrystallization
is
corn plete.
(4
74
IVT Course
Federal Aviation Authority
April, 1998
Introduction to Metallurgy
A-39
l
For P
l
TYP
tern
ure Metals
tally:
0.3 - 0.5 of absolute melting
Derature (see plot next slide)
. For alloys
+ Must be experimentally
determined
75
K
e
g 1500
E
5
s 1000
.-
i
.-
z
500
P
8
u
0
OR
I-
t
K = OC + 273
3000
OR=OF+460
JO00
540
1 1
L
oI*Y~
I-460’
0
2000
4000
6000
OR
0
1000
2000
3000
OK
1227 2
h
E
727
i
s
‘3
w
227
i
Fz
iii
-273 u
Melting
temperature
76
. Finer recrystallized
grain sizes
+ Higher strength
+ Lower ductility
(usually)
l
Coarse recrystallized
grain sizes
favored
by
l
Less extensive
mechanical
working
+ Higher annealing
temperatures
l
Long annealing
times
l
Stringers
remain (see next slide)
77
Microstructure
Before
(a) and After (b) recrystallization
78
IVT Course
Federal Aviation Authority
April, I998
Introduction to Metallurgy
A-4 I
Cold & Hot WoMing
l
Two
conditions
define hot working
+ Temperature
2 recrystallization
temperature
+ Rate of recrystallization
2 deformation
(strain hardening)
rate
l
Hot working microstructures
l
Recrystallized
grains
+ Stringers remain
l
Room temperature working
+ Can be hot working
-For low melting metals (e.g., Pb)
79
Undeformed
recrystallization
l
Lower energy inputs
+ Lower Strength at elevated temperatures
l
Continuous
recrystallization
-Keeps
strength
low
l
More reductions
possible
+ Higher ductility
at elevated temperatures
+ Continuous
recrystallization
-Keeps
ductility
high
81
l
Better
dimensional
TEMPER ROLL DESIGNATIONS
control
Copper 8 Its Alloys
. Better
surface
quality
Temper
% Cold reduction
114 hard
10.9
l
No elevated temperature
112 hard
20.9
oxidation
314 hard
29.4
l
Suitable
for hot, short
full hard
37.1
materials
extra hard
spring
60.5
50.1
+ e.g., high S steels
extra spring
68.6
- FeS melts at grain
special spring
75.1
boundaries
super spring
80.3
- Grains pull apart, not deform
. Higher
strength
4 Proportional
to % cold work (see chart)
02
IVT Course
Federal
Aviation
Administration
April,
1998
Introduction
to Metallurgy
. For production of standard mill products
+ Bar (round, hexagonal,
square, flat)
+ Rod, wire
l
Plate, sheet and foil
+ Shapes (l-beam, channel,
angle)
+ Tube and pipe
+ Billets (reforging
stock)
. By rolling, forging, drawing, and extruding-
l
To convert standard mill products to
+ Near-net shape products
+ More desirable
configurations
l
By ring rolling, upset and closed die
forging, sheet metal forming, ,many
others
l
Strengthening:
Providing
means to
resist slip
l
Resistance
to slip*
:
- strength
and hardness t
- ductility
#.(usually)
I
.
05
l
Dispersion
hardening
l
Strain hardening
. Grain size
. Solid solution
strengthening
l
Second phase hardening
l
Heat treatment
66
IVT Course
Federal Aviation Administration
April, 1998
Introduction to Metallurgy
A- 45
0