30Mn7Al汽车钢的力学性能与微观结构  

Microstructure and mechanical properties of 30Mn7Al automobile steel

作　　者：孙国强[1] 张杭州 康庆宇 杨沐鑫[2,3] 宁小智 吴林[1] SUN Guoqiang;ZHANG Hangzhou;KANG Qingyu;YANG Muxin;NING Xiaozhi;WU Lin(Department of Structural Steels,Central Iron and Steel Research Institute,Beijing 100081,China;State Key Laboratory of Nonlinear Mechanics,Institute of Mechanics,Chinese Academy of Sciences,100190 Beijing,China;School of Engineering Science,University of Chinese Academy of Sciences,100049 Beijing,China)

机构地区：[1]钢铁研究总院有限公司工程用钢研究所,北京100081 [2]中国科学院力学研究所非线性力学国家重点实验室,北京100190 [3]中国科学院大学工程科学学院,北京100049

出　　处：《金属功能材料》2022年第6期119-128,共10页Metallic Functional Materials

基　　金：国家自然科学基金资助项目(51601204)。

摘　　要：提出一种成分为0.3C-7Mn-0.5Al (质量分数,%)的新型第三代汽车钢,通过20%~65%冷轧及后续625~675℃退火处理,获得近等比马氏体/亚稳奥氏体双相组织,具有1.0 GPa以上拉伸屈服强度,以及60~75 GPa·%强塑积(抗拉强度与断后伸长率之积)。原位拉伸观测表明,冷轧退火态样品表现出多重非均匀塑性变形特征:在初始塑性应变阶段,显示出屈服降及吕德斯应变平台;在随后的加工硬化硬化阶段,产生动态应变时效诱导应力阶跃。通过变形微结构的EBSD、TEM和3D-APT观测指出,动态微带变形及局部相变传递使样品在更大应变范围内持续应变硬化,是实现其优异力学性能主要微观机制。A novel medium-Mn automotive steel has been designed to achieve unprecedented mechanical properties with tensile yield strength above 1.0 GPa and the product of strength and elongation exceeding 60-75 GPa·%. The tensile behavior is characterized by inhomogeneous deformation, which shows an incipient yield drop effect followed by a large Lüders straining and then several Portevin-Le Chatelier bandings during work-hardening stage. The multiple work-hardening mechanisms behind the unique mechanical properties are revealed by EBSD, TEM, 3 D-ATP, and in-situ DIC observations. These results indicated that the inhomogeneous martensitic transformation occured only within the local deformation zone, and only a small amount of martensite was required for the generation and propagation of Lüders and PLC microbands, which could provide a sustainable transformation-induced plasticity(TRIP) effect prolonging to a larger strain range. Consequently, not only the microband propagation, but also its induced local phase transitions played an important role in the multiplication of mobile dislocations, both of which provide a high density of mobile dislocations to enable strong strain hardening capabilities and the resulting unique mechanical properties.

关 键 词：第三代汽车钢 加工硬化 吕德斯变形 动态应变时效 TRIP效应 

分 类 号：TG142.1[一般工业技术—材料科学与工程]