304HC不锈钢钢丝形变诱导α′-马氏体相变及断裂机制  

Study on deformation inducedα′-martensitic transformationand fracture mechanism of 304HC stainless steel wire

作　　者：徐杨[1] 宋仁伯[1] 王宾宁 张磊峰[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083

出　　处：《塑性工程学报》2015年第4期154-160,共7页Journal of Plasticity Engineering

摘　　要：通过X射线衍射、扫描电镜和透射电镜等手段,研究冷拔过程中304HC不锈钢钢丝马氏体相变规律,并对马氏体相变过程中材料的断裂机理进行研究。结果表明,实验用钢形变马氏体的最高转变温度为57.9℃,镍当量为18.7%,满足形变诱导马氏体相变的温度条件和材料条件;随着马氏体相变的进行,试样的抗拉强度增加,延伸率下降;形变诱导马氏体相变的形核位置在孪晶与马氏体的交界面,位错弯曲缠结,形变孪晶协调变形,α′-马氏体在剪切带处切变形核,聚集形成马氏体板条;随着马氏体转变量增加,试样断裂类型由韧性断裂逐渐变为混合断裂;同时,在载荷较小时材料中的Al2O3夹杂与基体分离或本身开裂而形成微孔,随着载荷的增加,碳化物第二相阻碍位错运动并引起应力集中,变形不协调导致微孔长大、聚合,最终形成宏观裂纹。By means of XRD, SEM, and TEM. the rule of martensitic transformation of 304HC stainless steel wire during cold- drawing was studied, and the fracture of material and the mechanism were also studied during martensitic transformation. The experimental results show that the highest transformation temperature of deformation induced martensite of steel is 57.9 ℃. The equivalent of nickel is 8.7 %. They meet the temperature and material conditions of deformation induced martensitic transforma- tion. The tensile strength of specimen increases and the elongation decreases with the martensitic transformation. The nucleation site of deformation induced martensitic transformation is on the interface between twin and martensite. Then dislocations bend and tangle. Strain-twins deform harmonically, α′-martensites nucleate in the shear band and gather to form martensitic lath. The type of fracture changes from ductile fracture to mixed fracture gradually with the increasing amount of martensitic transformation. Al2O2 inclusion separates from the matrix and cracks when the bad is small. Then they form micro pores. The second phase of carbide hinders dislocation motion and causes stress concentration with the increase of load. After that, the micro pores grow up resulted from inharmonious deformation. They aggregate together. In the end, the macroscopic fractures form.

关 键 词：304HC不锈钢 冷拔 马氏体相变 形核机理 断裂机制 

分 类 号：TG356.4[金属学及工艺—金属压力加工]