Effects Of Aging Treatment And Plastic Deformation On Microstructure And Properties Of Alloying High Manganese Steel

As one kind of traditional wear-resistant materials, high manganese steel performskey feature of strain hardening and is widely used in mechanical equipment of mine,metallurgy, railway, construction materials, electricity, coal and so on. A fullyaustenitic microstructure is obtained only after a water toughening treatment.Hardness of high manganese steel with water-toughening is at a low level. When it issubjected to impact and abrasive wear, surface of work piece suffers impact andcutting from abrasive, resulting in shear fracture, serious wear and effecting itsworking life. Aiming at above issue, effects of aging treatment and plasticdeformation on microstructure and properties of high manganese steel and themechanism of strain hardening were investigate in this paper by metallographicanalysis, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmissionelectron microscopy (TEM), frictional wear test and compression deformation test.The researches show that, carbides precipitate in the austenitic matrix of highmanganese steel after aging treatment. The precipitate carbides are mainly (Cr,Mn)7C3,combining with a certain amount of Fe3C and a small amount of VC,(Cr,Mn)23C6.The morphology of carbides show needle and rod-like and the maximum size is about200nm.(Cr,Mn)23C6presents spherical particles, and its diameter is about10nm.Along with improvement of aging temperature and prolonging of aging time, carbidescome to precipitate from the grain boundary and inside as well. As a result, whenaging at650oC for6h, austenite recrystallization appeared remarkably and the bestdispersion strengthening effects has been achieved.Compression deformation analysis finds that, after deformation, certaindeformation was taken place in austenite grains, resulting in some glide line,dislocation and stacking fault raised. On the whole, the values of R0.2、n、k assumeupward tendency with increasing aging temperature, which indicate strength and workhardening ability are improved with increasing aging temperature. It also shows thebest work hardening ability and superior yield strength when aging at650oC for6h.Meanwhile, water toughening samples have better work hardening ability than lowtemperature aging samples. There is no mechanical twin appearing in all compression deformation process. The main mechanism controlling a course of work hardening arehigh density dislocation tangles and stacking fault hardening. Deformation of samplespresents typical double n mechanical behavior. There is principal influence on n1stage from different aging treatment, the value of n1is greater comparing with n2.Frictional wear analysis shows that, the work hardening ability of water tougheningsamples should not play a full part in the process of frictional wear test. Consequently,the aging samples possess outstanding wear-resisting property. The weight loss ofhigh manganese steel samples which aging at650oC for6h is minimum, it acts outthe most excellent wear resistance. Moreover, the wear surface only brings out a littleamount of furrows, certainly not peeling-off and accumulating. High manganese steelperforms typical abrasive wear, therefore, possesses remarkable wear resistance.