残余奥氏体及其机械稳定性与钢强韧性关系的研究

INVESTIGATION ON THE RELATIONSHIP BETWEEN STRENGTH AND TOUGHNESS OF STEELS AND RETAINED AUSTENITE AND ITS MECHANICAL STABILITY

钢中残余奥氏体发生应变诱发马氏体相变的百分量与拉伸应变量的对数呈线性关系,用直线斜率的倒数Ks值可表示残余奥氏体机械稳定性的大小。提高钢中残余奥氏体量及其机械稳定性是改善钢强韧性的有效途径之一。残余奥氏体发生应变诱发马氏体相变吸收能量是提高钢韧性的主要原因。在低碳贝氏体钢中,以M—A岛形式存在的残余奥氏体因受岛中马氏体的强化作用使屈服强度保持较高水平,而残余奥氏体在拉伸的均匀塑性变形阶段因应变诱发相变形成的马氏体使钢的抗拉强度提高。

There is established a linear dependence of percent of strain induced martensite transformation of the retained austenite in the steel upon tensile strain The mechanical stability of retained austenite can be indicated by Ks,the reciprocal of the strainghe line slope. It is one of effective methods improving the strength and toughnees that the amount of retained austenite and its mechanical stability is increased. The strengthening and toughening mechanism of the retained austenite has been studied in this paper. The toughness of the steel is improved by re- tained austenite which absorbs energy in induced martensite transformation. In low carbon bainitic steels,the ratio of yield strength to ultimate strength is remained a high vlue because the retined austenite in M-A islands is strengthened by martensite in the islands. The ultimate tensile strength is increased by the martensite formed by strain induced transformation of retained austenite in uniform plastic deformation of tensile.