Study On The Performance Of New Type Low Alloy Martensitic Wear Resistance Steel With High Strength And High Toughness

One novel types of heat treatment process, quenching and partitioning process (Q&P process) recently has been carried out, Q&P process has been further studied, then quenching, partitioning and temper process (Q-P-T process) has been carried out based on Q&P process. High strength and high toughness in martensitic steel can be obtained by Q-P-T processing. Q-P-T process is a novel technology to develop the high strength and high toughness martensitic steel.In this paper, quenching, partitioning and temper process (Q-P-T) and quenching and temper process (Q-T) are applied in the low alloy wear resistance steel ADVANS 450W(?) and ADVANS 550W(?) and ADVANS 600W(?). Microstructure of materials is analyzed by scanning electron microscope (SEM) and optical metallographic microscope (LOM), mechanical properties are investigated. And the impact abrasive wear characteristics of materials are tested on MLD-10 type three-body impact abrasive wear tester under different impact energy, the volume fraction of retained austenite in the wear surface of samples is measured by using X-ray diffraction before and after wear test. After wear test, curve of micro-hardness of subsurface layer of samples is measured by micro-hardness tester, the wear mechanism is analyzed by scanning electron microscope (SEM). Final results of the experiments are:(1) Upon suitable heat treatment, uniform and meticulous martensite lath, and retained austenite film are found in all low alloy wear resistance steel with ideal mechanical properties. And Q-P-T process remarkably improves the plasticity and toughness of low alloy martensitic steel in our study.(2) By Q-T processing and Q-P-T processing, the strength of steel ADVANS 450W(?) reaches 1450～1550MPa, hardness reaches HRC45, and Akv(40℃) reaches 50～65J, the strength of steel ADVANS 550W(?) reaches 1700-2000MPa, hardness reaches HRC52-55, and Akv (-40℃) reaches 20-30J. By Q-T processing, the strength of steel ADVANS 600W(?) reaches 2250MPa, hardness reaches HRC57.6, and Akv (-40℃) is about 13J.(3) Under 0.5J-3.5J impact energy, abrasive wear resistance of low alloy martensitic steel is proved almost 1.4 times higher to that of high manganese steel ZGMn13, therefore it's possible materials to replace high manganese steel on track.(4) In our study, wear resistance of the low alloy martensitic steel increases with increasing hardness, under the condition of three body impact abrasive wear. The impact abrasive wear resistance of steel increases with increasing impact toughness provided with basically equal hardness.(5) The reasons of weight loss in materials are micro-ploughing and micro-cutting, micro-fatigue and micro-cracking, and micro-spalling because of subsurface micro-cracking. Under 0.5J～1.5J impact energy, primary wear mechanism of low alloy martensitic steel is micro-ploughing and micro-cutting. It gradually changes into micro-fatigue and micro-cracking with increasing impact energy, and turns into micro-fatigue and micro-cracking under 2.5J-3.5J impact energy.