resistance to abrasive wear

(Lever, Rhys 1968; Vocel 1983; Friction and Wear Testing 1987; Blau 1992). Testing equip- ment for abrasive wear resistance determination is usually classified according to the contact mode of the sample with free or bonded abrasives. In prac- tice, the testing machines with abrasives bonded to cloth (Fig. 1) are used most often. They are simple and reliable, with small variance in results. Their disadvantage is the variable quality of abrasive cloth. In the Czech Republic this testing method is standardised according to ČSN 01 5084:1974 (simi- lar foreign standards: STN 01 5084, ASTM G 132). The principle of the abrasive wear test using the pin-on-disk machine with abrasive cloth (ČSN 01 5084:1974; Fig. 1) is to wear the sample under pre- determined conditions. Using the apparatus with abrasive cloth the samples were of 10 mm diameter and 70 mm length. The test sample was pressed against the abrasive surface using the prescribed normal force. The wear path was a spiral on the disk, caused by the disk rotation and the radial feed of the sample, so the sample progressively moved over the unused abrasive along the prescribed track length.

The effect of destabilization heat treatment on the microstructure, hardness, fracture toughness and abrasive wear resistance of high chromium hardfacing was investigated. The results from the study shows that the hardness, frac- ture toughness and abrasive wear resistance are influenced by temperature of destabilization heat treatment and air and furnace cooling conditions, respectively. Destabilization treatment of materials by furnace cooling caused higher secondary carbides in the dendritic austenite whilst by air cooling it showed smaller particles of secondary carbide. Also, it was found that destabilization temperature at 1,000°C improves hardness compared with hardfacing after weld depositing. The study, however, indicated that Palmqvist fracture toughness method is a useful technique for measuring the fracture toughness of high chromium hardfacing compared to Vicker’s hardness method.

Volume loss of all grades is shown in Fig 11. Fig 12 shows wear test samples.AISI 440C shows minimum volume loss while CA6NM shows maximum volume loss. In abrasive wear, the microstructure of material has significant importance. Better abrasion resistance in AISI 440C is attributed to carbides and martensitic matrix. Carbides in AISI 440C reduce material removal from surface by mechanisms like ploughing, cutting or brittle fracturing.

The ledeburitic tool steels which used to be used mainly for cutting and shaping tools nowadays are frequently used for a manufacture of injection moulds, moulds for pressure castings of aluminium alloys and for moulds for ceramics processing. The article deals with fi ndings of ledeburitic tool steels resistance against abrasive wear. For the tests there were prepared the test samples of ledeburitic tool steels 19 436 and 19 573 (both according to ČSN). Moreover there were prepared the samples from structural abrasion resistant material Hardox 450 and from unalloyed structural steel 11 373 (according to ČSN). A wear resistance was examined by means of a laboratory test with an abrasive cloth and the Bond’s device. Herea er the article deals with a possibility of utilisation of ledeburitic alloyed steels for a manufacture of tools for a land processing. For the examination of a resistance against wear in land there was made a plough test in which the tested samples were mounted on plough blades. By means of both the laboratory and operational tests there was found multiple higher resistance against wear of ledeburitic tool steels rather than of structural steels. During a land processing there was found unsuitability of steels processed for a maximum hardness, which came out as fractures of several samples.

Wear can be defined as: “The progressive loss of substance from the operating surface of a body as a result of relative motion of two surfaces with respect to each other”[5]. Kloss et al[6] stated that it is a complicated mechanical, thermal and chemical process and is therefore present in an extremely broad range of situations; from the impeller of a pump to the rotating components in a motor and leading edge of a cutting tool. The loss of material has an adverse effect on the working life of the machine, tool or surface that is exposed to the wear process. Wear models generally predict the reaction of a material to different wear situations and to forecast the rate of material removal or MRR from the surface of a body. Classical wear theory begins by considering the rate of material removal as a function of the sliding speed of the surfaces, the hardness of the material, the load applied and the probability of the material to produce a wear particle in a given contact and mechanical situation[7, 8]. There are four main theories which can used as a basis to begin a wear model: a mass balance approach, an energy balance approach, a stress/strain analysis and a contact mechanics approach to determine material behavior. Wear may occur in a number of different forms and these processes differ from one another when you consider the bodies which are in contact, the way in which material is removed and what is the amount of material removed. These processes do not always occur exclusively i.e. several might be present in a given situation.

Kverneland ploughshares and reversible points are of top quality, they exhibit both outstanding resistance to abrasive wear and resistance to impact loading and strokes. Given a suitable heat treatment, the wear of working tools made of austempered ductile iron (ADI) is comparable with that of original Kverneland working tools. An appropriate combination of chemical compo- sition and heat treatment can yield in ductile irons an optimum combination of strength, toughness and wear resistance for different ploughing conditions. Working tools can be made of ADI at 50% of the cost of original tools. In soil conditions corresponding to the experiment this represents in the case of ploughshares a saving of CZK 27 per ha. Casting ductile-iron working tools of complicated shapes can be economically advantageous even in small batches. However, in the case of soils con- taining large stones it cannot be excluded that plough- shares and reversible points made of ADI will break.

Before the abrasive wear test, all specimens were cleaned with acetone and then weighed on a me- chanical balance (type PRL TA 14) with an accuracy of ± 0.05 mg. The laboratory tests of the relative wear resistance were carried out using the pin- on-disk machine with the abrasive cloth according to ČSN 5084. The pin-on-disk machines are used most often, the simplicity and reliability being their advantages. The results variance is relatively small. The variable quality of the abrasive cloth must be continuously compensated by the use of etalons. The pin-on-disk testing machine (Figure 1) consists of the uniform rotating disk whereon the abrasive

hypoeutectic 16 mass % Cr cast irons without and with Mo was investigated. After annealing, the specimens were austenitized at 1323 K for 5.4 ks and cooled by fan air cooling. The hardened specimen was repeatedly tempered, at most three times at 748 ­ 798 K for 7.2 ks. The abrasive wear resistance of heat-treated specimens was evaluated using a Suga wear tester (two-body-type abrasive test). In the as-hardened state, the hardness did not change but the V £ increased gradually with an increase in the Mo content. In the tempered state, the hardness curves showed a secondary hardening as the t N increased due to the precipitation of secondary carbides and transformation of destabilized austenite to martensite.

Abrasive wear resistance of ledeburitic overlay materials is much better than of martensitic ma- terials (see Figures 15 and 16). The typical proper- ties are a high natural hardness and owing to this abrasive wear resistance, too. The cause is the heterogenity of structural constituents which make an island effect. Especially the hypereutectic cast irons, which contain long thin needles carbidics of in though eutectic, are very suitable for hard condi- tions of wear by mineral abrasive. Partly cheaper white cast irons are used, which differ only by the higher Cr content (2 to 5%), partly high alloyed cast irons, which contain 20 to 35% Cr. Higher resistance at elevated temperatures is reached by a tungsten addition, higher corrosion and chemical effect resistance by a nickel addition. These alloys have mostly a high natural hardness, which does not vary using various surfacing methods. Their use is very wide, e.g. for part surfacings of machines for earth moving industry. But at the same time these overlays are relatively brittle and therefore the hard brittle overlay layers must be backed by tough materials.

The mild steel samples are carburized at 500 ℃ temperature and socking time up to 30 min. After tempered process different tests such as hardness, tensile stress, abrasive wear and toughness test were performed at different temperature. Test data was analyzed and the result is shows that mechanical and wear properties are improved. Results show that as carburization temperatures increases, as improvement in the mechanical and wear properties. After Experimental data investigation it is found that toughness decrease with increase in carburization temperature. So 940 ℃ are best suited for mechanical and wear properties of mild steel because it gives highest tensile strength, hardness and wear resistance. Experimental result shows that a simple heat treatment of solid carburizing process can improve the hardness, tensile strength and wear resistance of the mild steels.

Results showed that deep cryogenic treatment contributed to improved abrasive wear resistance plasma nitriding improved tribological properties of P/M high speed steel and reduced the effect of austenzing temperature 22 Shaohong Li et al. [2013],

In the contribution the results of abrasive wear resistance study of 10 types of plastics are published. The results are compared with the test results of 4 diff erent Fe alloys. The laboratory tests were carried out using the pin-on-disk machine with abrasive cloth, when the abrasive clothes of 3 diff erent grits were used. The wear intensity of all test samples was assessed by volume, weight and length losses at diff erent conditions. The part of carried out tests was the technical-economical evaluation, too. The prices of plastics were taken over from invoices.

Hardfacing materials of major volume of carbidic phase in the deposit are of a very good abrasion resistance. For usual temperatures, hardfacing materials on the basis of Fe-Cr-C are used, above all for their relatively low price. Complex deposit Fe-Cr-C-M (where M means Nb, W, Ti, Mo and their combination) are of higher abrasion resistance. The commercially produced hardfacing materials are usually of 3–5.5% carbon content (Atamert & Bhadeshia 1990; Asensio et al. 2003). By the use of these electrodes on the low carbon steel as substrate and one layer deposit, the hypoeutectic or eutectic structure is reached. In the case of complex alloyed deposit, the hypoeutectic structure with primary carbides of MC type (e.g. NbC, WC) oc- curs. The carbides M 7 C 3 with high Cr contents can be reached only in the second and next layers (Ping Lu et al. 2004; Chotěborský 2008; Jankauskas et al. 2008).

It has been reported that the abrasive wear resistance of the particle reinforced MMCs increase with the volume fraction of particles, under both high and low stress abrasive wear conditions 10 . On a weighted adjusted basis, many Zn-Al-based composite materials can outperform cast iron, steel, Al, Mg and virtually any other reinforced metal or

The steel presents a wide field of application. The abrasive wear resistance of steel relies mainly on the micro- structure, hardness as well as on the abrasive material properties. Moreover, the selection of a abrasion-resistant grade of steel still seems to be a crucial and unsolved problem, especially due to the fact that the actual operating conditions can be affected by the presence of different abrasive materials. The aim of this work was to determine the effect of different abrasive grit materials i.e. garnet, corundum and carborundum on the abrasive wear result of a commonly used in industry practice steels i.e. S235, S355, C45, AISI 304 and Hardox 500. The microstructure of the steel was investigated using light optical microscopy. Moreover, hardness was measured with Vickers hardness tester. Additionally, the size and morphology of the abrasive materials were characterized. The abrasion tests were conducted with the usage of T-07 tribotester (dry sand rubber wheel). The results demonstrate that the hardness and structure of steels and hardness of abrasive grids influenced the wear results. The abrasive wear behavior of steels was dominated by microscratching and microcutting wear mechanisms. The highest mass loss was obtained for garnet, corundum, and carborundum, respectively. The usage of various abrasives results in different abrasion resistance for each tested steel grade. The AISI 304 austenitic stainless steel presents an outstanding abrasive wear resistance while usage of corundum and Hardox 500 while using a garnet as abrasive material. The C45 carbon steel was less resistant than AISI 304 for all three examined abrasives. The lowest resistance to wear in garnet and carborundum was obtained for the S235JR and S355J2 ferritic-perlitic carbon steels and in corundum for Hardox 500 which has tempered martensitic structure.

mechanical balance of an accuracy of ± 0.05 mg. The laboratory tests of the relative wear resistance were carried out using the pin-on-disk machine with the abrasive cloth (Al 2 O 3 , 1800–2300 HV, grit 120) ac- cording to ČSN 01 5084. The pin-on-disk machines are used most often. The simplicity and reliability are their advantages. The results variance is rela- tively small. The variable quality of the abrasive cloth must be continuously compensated by the use of etalons. The pin-on-disk testing machine (Figure 3) consists of a uniform rotating disk whereon the abrasive cloth is fixed. The specimen tested is fixed in the holder and pressed against the abrasive cloth with the weight of 2.35 kg. The screw makes the ra- dial feed of the specimen possible. The limit switch stops the test. During the test, the specimen moves from the outer edge to the centre of the abrasive cloth and a part of the specimen comes in contact with the unused abrasive cloth, namely 1.25 mm/1 revolution.

Analysis of the Structure and Abrasive Wear Resistance of White Cast Iron With Precipitates of Carbides. Archives of Metallurgy and Materials , 2013, vol[r]

Abstract: The abrasive wear resistance of martensitic overlays is the function of many variables. The hardness is one of the variables. This fact is raised by the possibility of carbidic phases separating from the austenite in the course the overlay layer cooling and by the possibility of the further martensite disintegration and carbidic phases precipitation. The paper is engaged in the hardness and abrasive wear resistance problems of one-layer martensitic overlays.

DOI: 10.4236/wjet.2019.73036 514 World Journal of Engineering and Technology on rough surfaces [4] [5]. [6] studied the wear behavior of different metal mate- rials. According to the shape of the abrasive grains, the abrasive grains were simplified into spherical abrasive grains [7], conical abrasive grains [7], round table abrasive grains [8], and pyramid abrasive grains [9]. The different wear factors of the above abrasive particles are based on the wear of the smooth plane, ignoring the effects of repeated scratches. Then, whether repeated friction and one friction will cause different wear changes has attracted our attention. This paper mainly analyzes the hemispherical abrasive particles and studies the sec- ondary friction of the abrasive particles.

Operating reliability of agricultural, transport and construction machines is in a considerable degree infl uenced by corrosion and wear. These sorts of damage signifi cantly infl uence the costs for the restoration of mechanical components, as well as their service and repairs. This article deals with comparing the abrasive and erosive wear of technical materials (so steel, wear-resisting steel, ledeburitic cast-iron, cemented carbides). A test of the abrasive wear by means of bound particles was carried out on an apparatus with a corundum abrasive cloth. The erosive wear was made in a testing mechanism manufactured by the fi rm Kovo Staněk Ltd., which simulated the operating conditions by jetting with both spheroidal granulate and angular crushed material.