Effect of temperature on friction and wear of prehardened tool steel during sliding against 22MnB5 steel

Abstract

Mechanical components in tribological systems exposed to elevated temperatures are gaining increased attention since more and more systems are designed to operate under extreme conditions. In hot metal forming, the effect of temperature on friction and wear is especially important since it is directly related to process economy (tool wear) and quality of the produced parts (friction between tool and workpiece). This study is therefore focused on fundamental understanding pertaining to the tribological characteristics of prehardened hot work tool steel during sliding against 22MnB5 boron steel. The tribological tests were carried out using a high temperature reciprocating sliding friction and wear tester under a normal load of 31 N (corresponding to a contact pressure of 10 MPa), a sliding speed of 0·2 m s^?1 and temperatures ranging from 40°C to 800°C. It was found that friction coefficient and specific wear rate decreased at elevated temperature because of formation of compacted wear debris layers on the surfaces.     

The sliding wear of 316 stainless steel in air in the temperature range 20–500°C

The friction and reciprocating wear of 316 stainless steel in air has been investigated in the temperature range 20–500°C at constant load using a standard pin and flat geometry. A marked change in wear behaviour occurred above 300°C. From room temperature to 300°C the wear rate decreased slowly with increasing temperature. This was accompanied by an increasing fraction of oxide in the wear debris. At 300°C the debris consisted entirely of oxide with the α Fe₂ O₃ structure. In this temperature range wear can be explained essentially in terms of mild wear. Above 300°C the wear rate decreased by an order of magnitude and was accompanied by a severely distorted wear surface. There was a high proportion of metallic particles in the wear debris. The surface roughening occurs at an early stage of wear and stops when glazed oxide regions form. The low wear rate is explained in terms of the high hardness of the glazed load-bearing areas and re-incorporation of wear debris into the wear scar.     

Investigation into the wear behaviour of Stellite 6 during rotation as an unlubricated bearing at 600 °C

The wear behaviour of Stellite 6 was studied during rotational sliding in a bespoke bearing rig at 600 °C for times between 2 min and 12 h. Six stages of wear were identified: (i) formation of a mixed oxide ‘glaze’, (ii) cobalt and chromium elemental diffusion to the ‘glaze’ surface forming chromium- and cobalt-dominated oxide layers, (iii) oxygen diffusion into the ‘glaze’ leading to a chromium-dominated oxide layer at the ‘glaze’/substrate interface, (iv) spallation of the ‘glaze’ through chemical failure, (v) re-formation of the ‘glaze’ and (vi) elemental diffusion within the ‘glaze’, again resulting in discrete oxide layer formation.     

Materials transfer and formation of mechanically mixed layer in dry sliding wear of metal matrix composites against steel

The wear behavior of a composite of a pure Al matrix reinforced with 20 vol% SiC particles against quenched 1045 steel was investigated. Material was found to transfer from the counterface to the wear surface of the composite, where a mechanically mixed layer (MML) was produced. A new mechanism, named the debris burial mechanism, for the formation of the mechanically mixed layer (MML) is proposed and discussed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Experimental investigation of the effect of the material damage induced in sheet metal forming process on the service performance of 22MnB5 steel

The use of ultra-high strength steels through sheet metal forming process offers a practical solution to the lightweight design of vehicles. However, sheet metal forming process not only produces desirable changes in material properties but also causes material damage that may adversely influence the service performance of the material formed. Thus, an investigation is conducted to experimentally quantify such influence for a commonly used steel (the 22MnB5 steel) based on the hot and cold forming processes. For each process, a number of samples are used to conduct a uniaxial tensile test to simulate the forming process. After that, some of the samples are trimmed into a standard shape and then uniaxially extended until fracture to simulate the service stage. Finally, a microstructure test is conducted to analyze the microdefects of the remaining samples. Based on the results of the first two tests, the effect of material damage on the service performance of 22MnB5 steel is analyzed. It is found that the material damages of both the hot and cold forming processes cause reductions in the service performance, such as the failure strain, the ultimate stress, the capacity of energy absorption and the ratio of residual strain. The reductions are generally lower and non-linear in the former process but higher and linear in the latter process. Additionally, it is found from the microstructure analysis that the difference in the reductions of the service performance of 22MnB5 by the two forming processes is driven by the difference in the micro damage mechanisms of the two processes. The findings of this research provide a useful reference in terms of the selection of sheet metal forming processes and the determination of forming parameters for 22MnB5.     

Influence of temperature of sub-zero treatments on the wear behaviour of die steel

This study examines the influence of temperature of sub-zero treatment on the wear behaviour of AISI D2 steel. A series of dry sliding wear studies have been made under constant normal load at varying sliding velocities. Emphasis has been laid to understand the operative modes and mechanisms of wear by the estimation of specific wear rates and detailed characterizations of the worn surfaces, wear debris and subsurfaces with the help of scanning electron microscope (SEM) examinations coupled with energy dispersive X-ray (EDX) microanalyses. The obtained results unambiguously infer that lower the temperature of sub-zero treatment higher is the improvement in wear resistance. Wear resistance can increase by 1.5–125 times depending on sliding velocity while hardness increases only by 4.2% at the lowest temperature of sub-zero treatment (77 K) compared to the conventionally treated specimens. These results corroborate well with the reduction in retained austenite content associated with simultaneous increase in the amount of secondary carbide particles with lowering of sub-zero treatment temperature. The operative modes and mechanisms of wear are identified as either mild oxidative or severe delaminative, which depends on the temperature of sub-zero treatment and the sliding velocity of the wear test.     

Influence of test parameters on friction and wear results obtained in oscillating sliding tests with 100cr6 steel against sic‐based materials

In order to characterise materials for tribological applications, model tests with simple contact geometry are in widespread use. Friction and wear behaviour can be determined with high accuracy from this type of test. Tests with oscillating sliding motion have the advantage that only small‐sized specimens are required. However, the fact that the results of model tests are affected considerably by the choice of test parameters is often overlooked. In order to check the influence of test parameters on friction and wear results, tests were performed in which the relevant parameters (stroke, frequency, load, relative humidity of the surrounding air) were varied. Comparative studies with different SiC‐based materials (SiC, SiSiC, and SiC‐TiC) against steel (100Cr6) under unlubricated conditions at room temperature show that in all cases the relative humidity is an important parameter, influencing the friction and wear results substantially. Additionally, several parameters can modify friction and wear behaviour more or less significantly. The effects of test parameters on friction and wear are discussed here on the basis of the wear mechanism. Some of the consequences of this for planning test series and for the practical use of test results are noted.     

The influence of reciprocating sliding wear on the oxidation behaviour of Fe-12Cr steel

Medium-chromium ferritic alloys are used extensively in the boiler and core sections of advanced gas cooled reactors (AGRs). It was discovered in the early 1970s, that under certain conditions these alloys could undergo the phenomenon known as breakaway oxidation. In this type of oxidation the rate-limiting step is located at the oxide/metal interface rather than the more usual gas/oxide interface and results in linear oxidation kinetics. It has been shown that repeated removal of oxide layers can expose chromium-depleted metal to the oxidizing gas and promote nucleation of breakaway oxidation. The question has been addressed as to whether high temperature sliding wear processes can also disrupt the surface so as to make the material potentially susceptible to breakaway oxidation.High temperature reciprocating wear tests of Fe-12Cr material in both low and high pressure reactor gas have been caried out. As expected, compact adhesive load-bearing oxide and mixed oxide/metal beds form in wear regions. These contacting features wear at very low rates of less than 10⁻¹⁶m³ (Nm)⁻¹. It has also been demonstrated that preformed oxides wear at sufficiently low rates at high temperature as to preclude the possibility of exposure of the underlying metal to the reactor gas. It is thus unlikely that sliding wear processes will accelerate the tendency for initiation of breakaway oxidation.     

Quantum-chemical investigation of the effect of grain-boundary segregation on wear resistance of steel

Quantum-chemical calculations of polyatomic clusters modeling the grain boundaries in the surface layer of steel are presented. Along with iron atoms, the clusters contain atoms of doping and impurity elements yielded to the boundary due to grain-boundary segregation. The effect of the chemical composition of segregants on the bond strength between the grains and, ultimately, on the wear resistance of steel is investigated. It is shown that the bond strength of segregated atoms with iron atoms in the surface layer of a metal is a substantial factor affecting the wear resistance.     

The effects of plasma nitriding process parameters on the wear characteristics of AISI M2 tool steel

The main aim of this work is to evaluate the effects of the plasma nitriding process on AISI M2 tool steel. In previous work, treatment time and temperature were varied to identify the treatment conditions for good wear behaviour. In the present work, the treatment time was fixed while temperature and gas pressure were varied. Samples were characterised by glow discharge optical spectroscopy, scanning electron microscopy, X‐ray diffraction, surface microhardness and wear test. The specimens nitrided at 400 and 900 Pa showed the best wear performance, which is possibly due to reduction of the friction coefficient and the low adhesive wear observed. Samples processed at 200 Pa showed spalling during the wear test, indicating a brittle surface. This revised version was published online in July 2006 with corrections to the Cover Date.     

The effect of rolling direction reversal on the wear rate and wear mechanism of pearlitic rail steel

The effect of different single and multiple rolling direction reversal (RDR) regimes on wear rate and mechanism is studied in this paper. Changes in structure deformation morphology and accumulated plastic strain are also analysed. Evidence that unidirectional rolling sliding contact can result in directional mechanical properties of the deformed layer is given. Results obtained under the test conditions used show that RDR has a beneficial effect on the wear rate of pearlitic rail steel. Multiple short RDR resulted in the lowest wear rate, less than half the unidirectional value.     

The effect of gross sliding fretting wear on stress distributions in thin W-DLC coating systems

The effect of fretting wear on stress evolution in a thin, hard diamond-like carbon coating deposited on a high strength steel is simulated using a finite element (FE) based method under gross sliding conditions. The effects of coating stiffness, thickness, and coefficient of friction are studied. The trailing edge tensile stress and the leading edge compressive stress are generally predicted to reduce with wear, while the shear stress at the interface is predicted to increase. An extrapolation procedure for predicting coating wear life is shown to provide accurate and slightly conservative estimates compared with explicit modelling to complete coating wear.     

Influence of the countermaterial on the dry sliding friction and wear behaviour of low temperature carburized AISI316L steel

Low temperature carburising (LTC) allows a significant hardness increase, with a consequent increase in wear resistance, without deteriorating corrosion behaviour. However, wear resistance strongly depends on contact conditions, therefore this work focuses on the dry sliding behaviour of LTC-treated AISI316L austenitic stainless steel against several countermaterials (AISI316L, LTC-treated AISI316L, hard chromium or plasma-sprayed Al₂O₃–TiO₂). LTC produced a hardened surface layer (C-supersaturated expanded austenite), which improved corrosion resistance in NaCl 3.5% and increased wear resistance, to an extent which depends on both normal load and countermaterial. The best results were obtained when at least one of the contacting bodies was LTC-treated, because this condition led to mild tribo-oxidative wear. However, LTC did not improve the behaviour in terms of friction.     

The influence of topography on the specific dissipated friction power in ultra-mild sliding wear: Experiment and simulation

Current political, economic and ecological guidelines demand the increase of power densities of nearly all machinery parts. In order to further lower the wear rate towards the ultra-mild sliding wear regime, an integral approach is needed, which has to regard contact conditions, surface topography, surface chemistry, as well as sub-surface properties. Still, there are no simple parameters to classify the performance of a tribosystem. In this study the area affected by tribocontacts is calculated by means of a three dimensional elastic–ideal plastic contact model. The surfaces are prepared by means of conventional machining procedures and characterized by scanning white light interferometry. The further input data as to normal and friction forces are derived by reciprocating sliding wear tests under boundary lubrication conditions of carburized steel against carburized steel and 52100 steel against case-hardened spheroidal cast iron. This contribution will depict the distinct influence of the topography on friction and ultra-mild sliding wear of common Fe-base materials and point out the marked importance of highly localized effects, which govern the acting mechanisms.     

Friction and wear behaviour of plasma-sprayed Cr2O3 coatings against steel in a wide range of sliding velocities and normal loads

This study investigates the influence of sliding speed and normal load on the friction and wear of plasma-sprayed Cr₂O₃ coatings, in dry and lubricated sliding against AISI D2 steel. Friction and wear tests were performed in a wide speed range of 0.125–8 m/s under different normal loads using a block-on-ring tribometer. SEM, EDS and XPS were employed to identify the mechanical and chemical changes on the worn surfaces. A tangential impact wear model was proposed to explain the steep rising of wear from the minimum wear to the maximum wear. The results show that the wear of Cr₂O₃ coatings increases with increasing load. Secondly, there exist a minimum-wear sliding speed (0.5 m/s) and a maximum-wear sliding speed (3 m/s) for a Cr₂O₃ coating in dry sliding. With the increase of speed, the wear of a Cr₂O₃ coating decreases in the range 0.125–0.5 m/s, then rises steeply from 0.5 m/s to 3 m/s, followed by a decrease thereafter. The large variation of wear with respect to speed can be explained by stick-slip at low speeds, the tangential impact effect at median speeds and the softening effect of flash temperature at high speeds. Thirdly, the chemical compositions of the transfer film are a-Fe₂O₃ in the speed range 0.25–2 m/s, and FeO at 7 m/s. In addition, the wear mechanisms of a Cr₂O₃ coating in dry sliding versus AISI D2 steel are adhesion at low speeds, brittle fracture at median speeds and a mixture of abrasion and brittle fracture at high speeds. Finally the lubricated wear of Cr₂O₃ coating increases sharply from 1 to 2.8 m/s.     

On the influence of test parameters on friction and wear of ceramics in oscillating sliding contacts

The tribological behaviour of different ceramics in contact with steel was studied for the case of oscillating sliding motion with a ball-on-disc apparatus. The influence of several test condition parameters was investigated by a systematic variation of the stroke, frequency, and normal load at room temperature in laboratory air at different levels of relative humidity. Each of the four parameters was varied in three stages. While the coefficient of friction was only mildly influenced by the operational variables, the coefficient of wear showed great variations and depended strongly on the humidity of the surrounding air. The effect of the operational variables and of the humidity on friction and wear varied for the different materials under investigation.     

Study on the protective effect of built-up layer in dry cutting of stainless steel SUS304

This work presents a systematic and comprehensive investigation of the protective effect of built-up layer (BUL) in dry cutting of stainless steel SUS304. A detailed examination of BUL and built-up edge (BUE) formation conditions, their formation mechanisms, and their protective effect was carried out at different cutting speeds (5–140 m/min), and different feed rates (0.02–0.1 mm/rev). The uncoated cemented carbide tool was used as a cutting tool. The dimensions of BUL/BUE and tool wear were measured by scanning electron microscope (SEM) and laser confocal microscopy (LCM). The protective effect of BUL/BUE was characterized using flank wear progression, as well as crater wear progression, cutting force analysis, and surface roughness analysis. As a result, it was found that BUE forms around the cutting edge at low cutting speeds (5–20 m/min), and BUL, which resembles a water drop, forms on the tool rake face at cutting speeds equal to or above 40 m/min. And a thin layer of flank built-up (FBU) can form on the tool flank face as the cutting speed increases from 40 m/min to 140 m/min. The BUL/BUE formation mechanism was also confirmed. It was revealed that BUL can be considered as a protective layer, which can not only prevent the tool rake face from wear but also decrease the tool flank wear, but BUE can only prevent the crater wear; and to a certain extent, the thin layer of FBU can also work as a protecting layer on the worn tool flank face in dry cutting of SUS304. It was also revealed that the height of BUL plays a very important role in its protective effect. Meanwhile, it was found that BUL and the thin layer of FBU have no or few influences on the amplitude variation of cutting forces and on the surface roughness. These results indicated that BUL can be used to realize the self-protective tool (SPT) in cutting of difficult-to-cut material such as SUS034. In addition, the research also proved that it is necessary to take the influences of BUL, BUE, and FBU formations on tool wear into account in the tool wear model in order to achieve high-precision prediction.     

The effect of silicon content and morphology on the wear of aluminium-silicon alloys under dry and lubricated sliding conditions

Improvement in the efficiency of the internal combustion engine has resulted in the increased usage of aluminium alloys and, in particular, aluminium-silicon as a substitute for cast iron. Despite the wide use of such materials in tribological environments little knowledge is available on the wear resistance of aluminium-silicon alloys. This paper investigates the wear performance of a range of binary aluminium-silicon alloys produced by a novel melt-spray technique. In addition, samples of the 11wt% silicon alloy were produced by conventional casting methods to elucidate the influence of silicon morphology on wear resistance. Pin-on-ring wear tests were carried out under dry and boundary-lubricated conditions. Surface analysis showed a similar wear mechanism under both conditions, these being: (1) oxidative and (2) metallic wear. Under boundary-lubricated conditions the load at which the transition to metallic wear occurred was increased. Raising the silicon content of the alloy was reflected in an increase in both wear resistance and transition load. Under dry sliding conditions the wear rate of the 11wt% alloy increased with a reduction in the silicon particle size, whereas under boundary-lubricated conditions the reverse was observed and the sand-cast alloy exhibited superior performance.     

Effects of microstructure and experimental parameters on high stress abrasive wear behaviour of a 0.19 wt% C dual phase steel

The present investigation is aimed at understanding the influence of the size and quantity of ferrite plus martensite on mechanical and abrasive wear properties in a 0.19 wt% C dual phase steel. The results indicate that the mechanical properties like strength, ductility and impact, as well as abrasion resistance of the samples are greatly influenced by the material and test conditions. For example, the samples involving prior annealing showed higher ductility but less strength over the normalized specimens. Also, the increasing intercritical annealing temperature led to superior strength associated with reduced ductility. The wear rate increased with load and abrasive size due to a larger depth of cut made by the abrasive medium. The wear rate decreased as sliding distance increased. The steel subjected to prior normalizing treatment attained superior wear resistance to that of the one subjected to prior annealing treatment. The wear rate also decreased with increasing intercritical annealing temperature from 765 to 805 °C with an exception that the steel treated at 805 °C exhibited wear rate comparable to the one treated at 765 °C when tested against coarser size (40 μm) abrasive.     

The effect of ion implantation on the sliding wear behaviour of ultrahigh molecular weight polyethylene against an oxidised titanium alloy Ti-6Al-4V

Pin-on-disk sliding wear studies have been conducted on untreated and ion-implanted UHMWPE against an oxidised Ti-6Al-4V alloy. Under water lubricated conditions no wear was measured. The enhanced mechanical and physical properties of the surface treated materials are responsible for the improved wear performance which may be of great importance to orthopaedic prostheses.