Deformation Hardening Behavior And Mechanism Of Typical High Manganese Wear Resistant Cast Steel Under Dynamic Load

High manganese wear-resistant cast steel is widely used in mining machinery,railroads,metallurgy and other fields because of its excellent work-hardening properties.The wear resistance and service life of high manganese wear-resistant cast steel are closely related to the service conditions,and the alloy tends to show very different wear resistance in different service environments.The ability to grasp the quantitative matching law between service conditions and strain hardening thresholds is the key to determining whether the advantages of high manganese wear-resistant cast steel processing hardening characteristics can be fully utilized to ensure wear resistance.However,the existing deformation hardening theory of high manganese wear-resistant cast steel mainly focuses on the qualitative study of deformation hardening law and mechanism,while the quantitative study involving deformation hardening theory is less focused.Based on this,this paper takes typical high-manganese wear-resistant cast steel Mn13Cr2 and Mn18Cr2 as the research object,and makes full use of the advantages of the Separate Hopkinson Press Bar technique(SHPB)in dynamic load simulation research to systematically study the deformation hardening behavior and mechanism of high-manganese wear-resistant cast steel under different dynamic loads.The mapping law between the work-hardening behavior and dynamic load of the experimental steel under different dynamic loads was elucidated quantitatively,and the critical threshold value of deformation hardening of the experimental wear-resistant cast steel was investigated,and the strain-hardening mechanism of the high-manganese wear-resistant cast steel under dynamic load was further explored by using electron backscatter diffraction(EBSD)and transmission electron microscopy(TEM)techniques.This study can provide experimental and theoretical references for the deep exploration of the wear resistance potential of high Mn wear-resistant cast steel or the rational selection of wear-resistant cast steel.The main research work and conclusions of this paper are as follows:(1)The mechanical properties of Mn13Cr2 and Mn18Cr2 high manganese wear-resistant cast steels were systematically studied by using water toughness treatment process,and the best mechanical properties interval and the best heat treatment process window were clarified.The results show that Mn13Cr2 high manganese wear-resistant cast steel has the best overall mechanical properties after "holding at 1000 ℃ for 2 h + water toughness treatment at 1040 ℃".Mn18Cr2 high manganese wear-resistant cast steel has the best overall mechanical properties after "holding at 1000 ℃ for 2 h +1020 ℃ water toughness treatment".(2)Based on the SHPB dynamic load simulation platform,the deformation hardening law of Mn13Cr2 high manganese wear-resistant cast steel under dynamic load was investigated.The results show that the deformation hardening process of Mn13Cr2 high manganese wear-resistant cast steel mainly consists of three stages: linear hardening,parabolic hardening and low strain hardening.When the impact load is 0.6 MPa,the critical load for the transition from the elastic strain to the linear hardening stage during the deformation of the alloy increases,and the hardening rate at the linear hardening stage is significantly higher than that at lower loads,and the work-hardening ability of the alloy is fully stimulated,and the alloy exhibits excellent work-hardening ability.(3)Based on the SHPB dynamic load simulation platform,the deformation hardening law of Mn18Cr2 high manganese wear-resistant cast steel under dynamic load was investigated.The results show that the deformation hardening process of Mn18Cr2 high manganese wear-resistant cast steel mainly consists of two stages,parabolic hardening and low strain hardening,while the linear hardening stage can be almost neglected.When the impact load is 0.6 MPa,the critical load for the transition from elastic strain to linear hardening stage during alloy deformation increases,and the stress state in the parabolic hardening stage is significantly higher than the distribution interval at lower loads,and the alloy exhibits excellent work-hardening ability.(4)The deformation mechanisms of two high manganese wear-resistant cast steels,Mn13Cr2 and Mn18Cr2,under dynamic loading were investigated by using EBSD,TEM and other research means,combined with the strain hardening law under dynamic loading.The results show that with the increase of impact air pressure,no TRIP effect phenomenon was found to exist for both alloys,and the internal dislocation density of the matrix increased significantly.The twin sub-structure appears under partial impact pressure,but the twin content does not show a certain regular variation.The work-hardening mechanism of the two typical alloys under dynamic loading is dominated by dislocation hardening mechanism and supplemented by twin hardening mechanism.