高碳高锰钢450℃时效处理后的拉伸断裂行为

摘要

The microstructure,tensile property,the characteristic of fracture morphology and the process of nucleation and expansion of cracks were studied by metallography analysis,tensile test and fracture morphology analysis.The test result show that the microstructure of the high carbon and high manganese steel treated by aging at 450℃ is consisted of a few discontinuous carbides existing on the austenitic grain boundary.The high carbon and high manganese steel with the microstructure behaves superior plasticity and high tensile strength.Its tensile strength and elongation can reach 981 MPa and 70％ respectively.Deformation twins are formed in fractured mafrix of the high carbon and high manganese steel,and fracture nucleation happens on the twin boundary and on the carbides on grain boundary.Cracks grow up along the twin boundary and grain boundary,and the fracture spreads by adjacent cracks attaching to each other,resulted in fracture.Fracture morphology of the high carbon and high manganese steel is fractured stone like,and many dimples exist on the fracture surface.%采用金相分析、拉伸实验以及断口形貌观察等分析手段研究了100Mn13高碳高锰钢450℃时效处理后的组织、拉伸性能、断口形貌特征及其裂纹形核与扩展过程.结果表明:高碳高锰钢水韧处理及450℃时效处理后的金相组织为奥氏体基体上存在有少量沿晶界呈不连续分布的碳化物.具有这样组织的高碳高锰钢仍具有优越的塑性和高的抗拉强度,其断裂后的抗拉强度和延伸率可分别达到981MPa和70％.拉伸断裂后的高碳高锰钢组织中出现了大量的孪晶,而且裂纹在孪晶界处以及晶界上的碳化物处形核,并沿晶界和孪晶界长大,相邻裂纹相互连接、扩展,直至断裂.拉伸断口微观形貌为石断状,其断裂面上存在有大量的韧窝.