摘要
通过采用扫描电镜及透射电镜等手段,观察并研究了TWIP钢在低周单轴循环对称拉压载荷下的疲劳断裂后的显微组织。结果表明:TWIP钢矩形试样的疲劳裂纹一般萌生于角部,从表面萌生时可能表现为多个疲劳源。在低周疲劳变形过程中,TWIP钢不但产生了形变孪晶,还产生了大量的微条带,其实质为细微孪晶片层和驻留滑移带。疲劳裂纹主要萌生于微条带对晶界和孪晶界的撞击引发的孔洞。孔洞串连接起来成为裂纹,夹杂物促进了裂纹扩展。随着裂纹的扩展,试样的承载面积不断减小,最终发生快速的韧性断裂。
Microstructure evolution of a TWIP steel after low cycle axial symmetric tension-compression fatigue fracture was observed and researched by SEM and TEM. The results indicate that the fatigue crack usually is initiated from the corner of the rectangle specimen of the TWIP steel. There may be more than one crack source when crack initiating from surface. Deformation twins and great amount of micro-bands,which are substantially sub-twin layers and persistent slip bands,generated during the fatigue deformation. The fatigue crack is mainly initiated at the holes which are formed by the crashes between micro-bands,twinning boundaries and grain boundaries. The holes link up to form crack,and the inclusions in the steel promote the propagation of cracks. With the propagation of crack,load bearing area of the specimen decreases until the occurence of fast final ductile fracture.
出处
《材料热处理学报》
EI
CAS
CSCD
北大核心
2014年第9期142-145,共4页
Transactions of Materials and Heat Treatment
基金
北京科技大学中央高校基本科研业务费专项资金资助项目(FRF-TP-11-005B)
宝钢汽车用钢开发与应用技术国家重点实验室开放课题基金-稀土对TWIP钢作用的基础研究
关键词
TWIP钢
低周疲劳
孪晶
驻留滑移带
裂纹萌生
TWIP steel
low cycle fatigue
twin
persistent slip band
crack initiation
