Three-body abrasive wear of fine pearlite, nanostructured bainite and martensite (original) (raw)
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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.
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.
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...
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.
Wear, 2016
In the present work, the wear behaviour of different steels has been investigated under a three body abrasive environment at room and elevated temperatures. High-silicon steel (0.25C-1.42Si) was austempered at 300 and 320°C in order to obtain two carbide-free bainitic steels with different mechanical properties. The same steel subjected to two different quench and temper heat treatments was used as a reference material for mechanical and wear testing. The steels were subjected to three-body abrasive wear by means of a high temperature continuous abrasion tester (HT-CAT). The tests were done at 25, 300 and 500°C respectively. All samples showed similar wear rates at room temperature. At 500°C, the material austempered at 320°C showed the highest toughness and the lowest wear rate. High temperature hardness and impact toughness tests showed that abrasive wear is not only influenced by hardness but also by the toughness of the material. Owing to their good strength/toughness combination CFB steels could prove to be an important material for abrasive wear applications.
Wear, 2018
In the current study, a high-carbon, high-silicon steel (1.21 wt% C, 2.56 wt% Mn, 1.59 wt% Si) was subjected to different heat treatments ((a) quenching from 800-1000°C; (b) quenching from 800-1000°C with further bainitizing at 250°C for 8 days), resulting in microstructures consisting (a) of austenite and martensite (up to 94 vol% austenite) or (b) of austenite, nanobainite, and tempered martensite (up to 39 vol% nanobainite). The work is carried out using SEM, XRD, microhardness measurement, surface profile characterization, and two-body abrasion testing. It was found that steel wear behaviour is strongly dependent on austenite volume fraction and its metastability to mechanically-induced martensite transformation under wear. Austenite enrichment with carbon (upon carbides dissolution or bainite transformation) inhibits mechanically-induced transformation leading to decrease in microhardness increment after wear test and to an increase in wear rate. Specimens as-quenched from 900-1000°C are found to have the highest wear resistance. This is attributed to the higher metastability of the retained austenite of these specimens. Nanobainite-containing specimens exhibit suppressed TRIP-effect under abrasion. The specimens containing 60-94 vol% of metastable austenite are by 1.5-1.8 times more wear resistant compared with the specimens consisting of 10-39 vol% nanobainite and 49-55 vol% of more stable austenite. Also, the relationship between wear behaviour and surface profile of the worn specimens is discussed.
Wear, 2020
This study aims to understand the effects of toughness and hardness on two-body wear of nanostructured carbide-free bainitic steels. For this purpose, three different steel grades were austempered at 250 • C to obtain carbide-free bainitic microstructures with different mechanical properties. The mechanical properties were determined in terms of fracture toughness and hardness. The wear tests were carried-out at three different loads with two different types of abrasive papers. The results show that a carbide-free bainitic steel with an optimum combination of hardness and fracture toughness exhibits the highest wear resistance. It has been seen that hardness is not the only parameter in determining the abrasive wear resistance and retained austenite has a beneficial effect on two-body abrasive wear.
A first evaluation of the abrasive wear of an austenitic FeMnAlC steel
Wear, 2004
Alloys of the FeMnAlC system have been primarily developed as possible alternatives to stainless steels for structural applications in moderately aggressive environments. Such alloys, when solution treated, are non-magnetic and present an austenitic structure that can be modified by thermal treatments. In this way, different combinations of mechanical strength, fracture toughness and physical properties can be obtained, and components for aeronautical and chemical industries are currently in use. Information concerning the performance of these alloys under wear conditions is still very limited, and the use of FeMnAlC alloys in applications where mechanical components are subjected to cavitation and abrasion conditions still require experimental data and fundamental research. The present study has been carried out to characterize the abrasive wear behavior associated to the different microstructures of this new kind of high Mn steel and to compare it with conventional steels. Microstructures were characterized by optical and atomic force microscopy, and samples subsequently subjected to a micro-abrasion test, together with samples of a AISI 304 stainless steel and a AISI M2 tool steel. It has been shown that when subjected to a controlled cooling process, the abrasion wear resistance of the austenitic FeMnAlC alloy was of the same level as the 304 stainless steel and of the M2 tool steel. This result has been explained in terms of the austenite decomposition that takes place during the controlled cooling process.
Influence of stress state on abrasive wear of steels
Wear, 1995
The resistance of materials to abrasive wear depends on many factors that can be generally classified as material-based or operating systembased. In the published wear models, the bulk stress state or stress history of worn material do not appear as influencing factors. Following the analogy with stress corrosion and fatigue, as well as with cyclic softening of steel materials, the possible influence of bulk stress state and stress history on abrasive wear of steels has been examined. Preliminary experiments were carried out using a scratch tester with a diamond indenter. Hypoeutectoid steel specimens were bent to obtain tensile or compressive stress and then scratched in situ under a normal load of 25-40 N. The results of the screening experiments indicate that the depth of grooves and the wear mechanism differ, depending on whether the specimens are under tension or compression. Tensile stress favours micro-cutting, while a compressive state apparently maintains microploughing. The pilot experiments, conducted with a hypereutectoid steel, indicate (with a confidence 80%) the significant influence of stress history, i.e. cyclic stressing, on abrasive wear. Further analyses, combined with detailed observation using scanning electron microscopy, have allowed discussion and explanation of these phenomena.
Materials Science and Engineering A-structural Materials Properties Microstructure and Processing, 2007
Effects of heat treatment on the high-stress abrasive wear response of 0.2% carbon steel have been investigated at varying applied loads, abrasive (SiC) sizes and sliding distances. The heat treatment involved intercritical annealing at three different temperatures between Ac 1 and Ac 3 followed by ice water quenching in order to produce a dual phase microstructure consisting of varying quantities of ferrite plus martensite. The wear rate increased monotonically with applied load irrespective of the heat treatment schedule. Further, the wear rate increased drastically when the abrasive size was increased from 15 to 27 m; a further increase in the abrasive size led to only a marginal increase in the wear rate. In general, the wear rate decreased with increasing sliding distance and attained a nearly stable value at longer sliding distances. Increasing intercritical annealing temperature resulted into higher martensite content, thereby leading to reduced wear rate. However, the extent of reduction in wear rate with martensite content has been found to change with the applied load and abrasive size. The present investigation clearly suggests that it is quite possible to attain desired combinations of bulk hardness and microstructure (ferrite plus martensite) that could greatly control abrasive wear properties in low carbon steel. The observed wear response of the samples has been explained on the basis of microconstituent-abrasive interaction during the course of abrasive action, degradation of the abrasive particles and the nature of various microconstituents, i.e. mechanical properties. of equivalent tensile strength is another interesting feature of the dual phase steels .