摘要
对一种C-Si-Mn-Cr合金钢,通过900℃奥氏体化20 min,空冷及280与370℃回火2 h,获得抗拉强度为1500 MPa的新型无碳化物贝氏体/马氏体(B/M)复相组织高强钢,采用C-T试样进行疲劳实验,测定了疲劳裂纹扩展速率(da/dN)及疲劳门槛值(△K_(th)),利用扫描电镜观测了疲劳裂纹在疲劳循环过程中的扩展路径,分析断口形貌与显微组织间的关系,结果表明,这种无碳化物B/M复相高强钢具有较高的△K_(th)值,并且能明显地降低da/dN,其原因在于B/M复相组织高强钢独特的精细组织结构及疲劳裂纹尖端的闭合抗力的提高。
The ultimate tensile strength of a novel carbide-free bainite/martensite duplex-phase high strength steel (C-Si-Mn-Cr steel) is above 1500 MPa after austenitizing at 900 degreesC for 20 min, then air cooling and tempered for 2 h at 280 degreesC and 370 degreesC, respectively. The fatigue crack propagation rate da/dN and threshold DeltaK(th) were measured using compact-tensile specimens, the fatigue crack propagation path during the cycling fatigue was observed by SEM, and the relationship between fatigue fracture morphology and microstructure was analyzed. The results show that the carbide-free bainite/martensite duplex-phase high strength steel has higher DeltaK(th) and lower da/dN, which originates from special microstructure and advanced closure resistance on the fatigue crack tip.
出处
《金属学报》
SCIE
EI
CAS
CSCD
北大核心
2003年第7期734-738,共5页
Acta Metallurgica Sinica
基金
国家重点基础研究发展规划资助项目G1998061513
关键词
贝氏体/马氏体复相高强钢
疲劳裂纹门槛值
疲劳裂纹扩展速率
闭合抗力
bainite/martensite duplex-phase high strength steel
fatigue crack threshold
fatigue crack propagation rate
closure resistance
