Regulation of retained austenite in medium Mn and high Ti content wear-resistant steel and effect on its wear resistance
Wear-resistant steel for construction machinery not only requires high wear resistance,but also should have good plasticity and toughness.Through the design of medium Mn alloy composition and annealing in two-phase region,the introduction of retained austenite(RA)in high Ti content martensitic wear-resistant steel can make the wear-resistant steel obtain good plastic toughness and wear resistance.The research results show that with the increase of annealing holding time in two-phase region at 630 ℃,the volume fraction of RA in-creased.After holding for 8 h,the volume fraction of RA of sample was 32.1％,and the elongation was 17％.During the tensile process,the work hardening rate curve of the samples annealed in the two-phase region first decreased and then increased slightly,then remained sta-ble,and finally began to decrease until the sample breaks.The increase of the work hardening rate was related to the strain-induced marten-sitic transformation.High work hardening rate was beneficial to the increase of elongation of the steel.Compared with the rolled sample,the hardness of the sample annealed in the two-phase region for 8 h was reduced by 120HV,but the relative wear resistance was increased by 23％.The wear morphology of the sample annealed in the two-phase region was grooves and spalling pits,while the wear morphology of the rolled sample has more plastic deformation fatigue spalling in addition to grooves and spalling pits.Because of the low elongation,poor plasticity and fatigue resistance of the rolled sample,the experimental steel was prone to spalling due to plastic deformation fatigue during repeated deform-ation.In addition,during the wear process,the RA in the two-phase region annealed sample will undergo phase transformation,resulting in phase transformation induced plasticity effect and increasing the work hardening rate.The work hardening rate in the later stage of tensile had a great influence on the wear resistance.The higher the work hardening rate was,the better the wear resistance was The X-ray results show that the volume fraction of retained austenite in the samples annealed in the two-phase region after wear will decrease by more than 50％.
medium Mn and high Ti content martensitic wear-resistant steelresidual austeniteannealing in two-phase regionwear resistance propertywork hardening rate
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