Two-body abrasion resistance of high-carbon high-silicon steel: Metastable austenite vs nanostructured bainite (original) (raw)
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Materials
A high-carbon, high-silicon steel (1.21 wt% C, 2.56 wt% Mn, 1.59 wt% Si) was subjected to quenching from 900 and 1000 °C, resulting in microstructures containing 60 and 94% of retained austenite, respectively. Subsequent abrasive wear tests of quenched samples were performed using two-body abrasion and three-body abrasion testing machines. Investigations on worn surface and subsurface were carried out using SEM, XRD, and microhardness measurement. It was found that the highest microhardness of worn surface (about 1400 HV0.05) was achieved on samples quenched from 900 °C after three-body abrasion. Microhardness of samples after two-body abrasion was noticeably smaller. with a maximum of about 1200 HV0.05. This difference correlates with microstructure investigations along with XRD results. Three-body abrasion has produced a significantly deeper deformed layer; corresponding diffractograms show bigger values of the full width at half maximum parameter (FWHM) for both α and γ alone sta...
Three-body abrasive wear of fine pearlite, nanostructured bainite and martensite
Wear, 2013
The abrasive wear of three metallurgical structures with radically different hardnesses have been investigated for the same steel. The particular steel concerned is a recent innovation capable of generating extremely fine distributions of crystals. The austenite in the alloy nevertheless has the capability of uniformly transforming into extremely fine pearlite, nanostructured bainite, and plate martensite. It is found that although the abrasion rates and wear coefficients are not very different for the three states, the mechanisms of abrasion are quite different. We report detailed characterisation experiments together with comparisons with commercially available steels subjected to identical tests.
Wear of fine pearlite, nanostructured bainite and martensite
2017
Abrasion is a form of wear prominent particularly in the agricultural, mining, mineral and transportation industries. The cost of abrasive wear to the national economy is estimated to be about 1% of the gross national product, and it can compromise the safety and reliability of engineering components. The mechanism of wear is complex and dependent on all the materials involved in the process, environmental conditions and many subtle factors such as the shape of the abrading particles. Many abrasion-resistant steels are based on a quenched and tempered martensitic microstructure, because the hardness of the steel should intuitively matter in determining the wear rate. Nevertheless, the relationship between the rate of material loss and steel hardness is unlikely to be monotonic.
Tribology International, 2020
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Wear, 2018
The three-body abrasive wear behavior of three ferrous alloys with different microstructures but similar hardness has been investigated using a standard dry-sand rubber wheel test (ASTM G65-16). Although the hardness of the alloys was similar, the abrasion rates are radically different owing to differences in abrasion mechanisms in their microstructures. A carbide-free bainitic steel having fine bainitic laths exhibited better abrasion resistance owing to the strain-induced transformation of austenite into martensite. Nano-scaled martensitic laths that formed on the surface resisted plastic deformation during abrasion and thereby increased the abrasion resistance. The microstructure containing bainitic ferrite undergoes extensive plastic deformation associated with a large quantity of dislocations, which in turn accommodates the strain of abrasion. The steel with a blockymartensitic microstructure had the least wear resistance. In that case, fragmentation and chipping comprised the prominent abrasion mechanism. The degeneration of a martensitic structure and its subsequent tempering radically reduces the hardness at the surface and makes it more susceptible to abrasion. Steel containing a mixture of bainite and martensite had intermediate abrasion resistance relative to the other two alloys.
Two-Body Abrasion Resistance of High-Carbon Metastable Austenitic Steels
METAL 2021 Conference Proeedings, 2021
This study presents the results of two-body abrasion tests on several high-carbon low-alloy steels initially consisting of a dual-phase microstructure containing metastable austenite and thermally induced plate martensite. The wear behavior of these metastable austenitic steels (MAS) is compared to commercial wearresistant steels. Some tested MAS showed specific wear rates (SWR) that are more than three times lower compared to that of a martensitic 30MnB5 (1.5531) and an austenitic X120Mn12 (1.3401) steel and even more than five times lower than the SWR of Hardox 450. Pre-and post-wear hardness measurements indicate that low wear rates in MAS are related to hardness increase during wear. MAS with post-wear hardness in the range of 900-1000 HV achieved the lowest SWR. A further increased post-wear hardness up to 1250 HV proved to be not beneficial and led to an increasing SWR. XRD measurements show significant changes in the phase fractions of the MAS sub-surface region due to an austenite-martensite phase transformation. SEM micrographs also show severe plastic deformation in the sub-surface layer and the wear tracks.
Metals, 2020
A novel high C high Si carbide free bainitic steel was developed for the production of cold work tools, knives, and rolls, requiring high hardness, toughness, as well as abrasive/adhesive wear resistance and resistance to galling at low costs. The steel was tribologically tested in dry sliding conditions under abrasive and adhesive wear mode, facilitated by using alumina and bearing steel ball as a counter-material, respectively. It was determined that carbide dissolution occurs under high contact pressures, thereby enriching the surrounding matrix with carbon and locally increasing the retained austenite content. The high retained austenite at the sliding interface increases the steels work hardening capacity and promotes superior wear resistance when compared to much more alloyed cold work tool steel, such as AISI D2. The steel has a high resistance to galling as determined by sliding against a soft steel bar due to its chemical composition.
Wear, 2005
In this work, the influence of the proportion of retained austenite in the abrasive wear resistance of a laser surface melted martensitic stainless tool steel is analysed. Samples of a 0.5 wt.% C, 13 wt.% Cr + Fe martensitic stainless tool steel were surface melted using a CW CO 2 laser. By changing the processing parameters, samples with proportions of retained austenite varying from 15 to 100% were produced. Microscale abrasive wear tests were performed in the samples. The wear behaviour of the laser melted samples was compared with that of a sample of the same steel in the conventional quenched and tempered condition. It was observed that the wear behaviour of the material depends on the proportion of retained austenite but also of the test conditions, namely of the applied load. For the lower test loads, it was observed that the material submitted to conventional heat treatment presents higher wear resistance; on the contrary, for the higher test loads, it was observed that some of the laser melted samples present a wear resistance higher than that of the conventionally treated material. The analysis of the worn surfaces shows that, in the laser surface melted samples, the stress-induced transformation of austenite into martensite plays an important role in the increase of the wear resistance of the material with increasing applied load.
Tribology Letters, 2003
A low (0.2%) carbon steel has been subjected to heat treatment to form varying quantities of ferrite plus martensite in its microstructure. This was achieved by holding the samples in the two-phase (ferrite plus austenite) region at three different temperatures (750, 780, and 810 °C) for a specific duration followed by quenching in ice water. In another exercise, the steel was also subjected to annealing treatment by austenitizing at 890 °C followed by furnace cooling for comparison purposes. The samples were subjected to low-stress (three-body) abrasion tests using an ASTM rubber wheel abrasion test apparatus at different wheel speeds (150, 273 and 400 rpm corresponding to linear speeds of 1.79, 3.26 and 4.78 m/s respectively) for different sliding distances at a fixed load of 49 N. Crushed silica sand particles of size ranging from 212 to 300 μm were used as the abrasive medium. The wear rate of samples decreased progressively with sliding distance until a (nearly) steady-state condition was attained. This was considered to be due to abrasion-induced work hardening of subsurface regions as well as the greater tendency of protrusion of the harder martensite/pearlite phase at longer sliding distances, thereby providing greater resistance to wear. Decreasing wear rate with increasing treatment temperature 750–810 °C could be attributed to the greater volume fraction of the hard martensite phase in the samples containing ferrite plus martensite. The lower wear rate observed in the case of the samples containing ferrite plus martensite over the annealed ones comprising ferrite and pearlite was attributed to the higher bulk hardness of the former. Increasing linear speed from 1.79 to 3.26 m/s led to an increase in wear rate. This could be attributed to greater tendency of the abrasive particles to create deeper scratches and scouping (digging). A reduction in wear rate with a further increase in the linear speed from 3.26 to 4.78 m/s could be due to a change in the mechanism of wear from predominantly sliding to rolling of the abrasive particles in view of the increased plastic deformability characteristics of the specimens due to higher frictional heating. The present investigation clearly suggests that it is possible to attain a desired combination of bulk hardness and microstructure (consisting of ferrite plus martensite) leading to optimum abrasion resistance in low-carbon steels. The quantity of the two phases in turn could be varied by suitably controlling the heat-treatment temperature.
2013
The present study is concerned with the potential of high carbon, high silicon steel grades isothermally transformed to bainite at low temperature (< 300 °C). A first part gives an overview of design principles allowing very high strength and ductility to be achieved, while minimising transformation duration. Wear and fatigue properties are then investigated for over ten variants of such material, manufactured in the laboratory or industrially. The results are discussed against published data. Tensile strength above 2 GPa are routinely achieved, with, in one case, an exceptional and unprecedented total elongation of over 20%. Bainite plate thickness and retained austenite content are shown to be important factors in controlling the yield strength, though additional, non negligible parameters remain to be quantified. Rolling-sliding wear performances are found to be exceptional, with as little as 1% of the specific wear rate of conventional bainitised 100Cr6. It is suggested that this results from the decomposition of retained austenite in the worn layer, which considerably increases hardness and presumaby introduces compressive residual stresses. Fatigue performance were slightly improved over 100Cr6 for one of the two industrially produced material, but significantly lower otherwise. Factors controlling fatigue resistance require further investigations.