摘要
为优化600 MPa级冷压桥壳钢的成分与组织性能,进一步提高车桥的疲劳服役寿命,利用热模拟试验机预制了桥壳钢的焊接热影响粗晶区(CGHAZ)组织,采用示波冲击法得到了CGHAZ的冲击韧性,通过维氏硬度计考察了CGHAZ的组织软化特征,通过电液伺服疲劳试验机测试了CGHAZ的疲劳裂纹扩展速率,利用激光扫描共聚焦显微镜(CLSM)、高温激光显微镜(HTLM)、扫描电子显微镜(SEM)以及电子背散射衍射(EBSD)研究了CGHAZ的组织演变,M/A的形态,大角度晶界分布和疲劳二次裂纹的扩展及其走向.结果表明,采用Nb-V成分体系的桥壳钢脆韧转变温度低于−20℃.当t8/5≤15 s时粗晶区组织不发生软化且疲劳二次裂纹在大角度晶界处发生明显偏转,其疲劳裂纹扩展速率相对Mn-Ti系和Ti-Nb系最低.
In order to optimize the composition and microstructure properties of 600 MPa cold-pressed axle housing steel,and further improve the fatigue service life of the axle,this paper uses a thermal simulation test machine to prefabricate the welding heat affected coarse grained area(CGHAZ)structure of the axle housing steel.The impact toughness of CGHAZ was obtained;the softening characteristics of CGHAZ were examined by a Vickers hardness tester;the fatigue crack growth rate of CGHAZ was tested by an electro-hydraulic servo fatigue tester;the laser scanning confocal microscope(CLSM),high temperature Laser microscopy(HTLM),scanning electron microscopy(SEM),and electron backscatter diffraction(EBSD)studied the structural evolution of CGHAZ,the morphology of M/A,the distribution of large-angle grain boundaries,and the propagation of fatigue secondary cracks and their trends.Studies have shown that the brittle-ductile transition temperature of bridge shell steel using the Nb-V composition system is lower than−20℃;when t8/5≤15 s,the microstructure in the coarse grain region does not soften and fatigue secondary cracks occur at large angle grain boundaries.Deflection,the fatigue crack growth rate is the lowest compared to Mn-Ti and Ti-Nb systems.
作者
张楠
赵阳
田志凌
郑江鹏
张书彦
李晓林
ZHANG Nan;ZHAO Yang;TIAN Zhiling;ZHENG Jiangpeng;ZHANG Shuyan;LI Xiaolin(Central Iron and Steel Research Institute,Beijing 100081,China;Anstell beijing research institute,Beijing,102211,China;Centre of Excellence for Advanced Materials,Dongguan 523808,China;Shougang Research Institute of Technology,Beijing 100041,China)
出处
《焊接学报》
EI
CAS
CSCD
北大核心
2020年第11期38-46,I0003,共10页
Transactions of The China Welding Institution
基金
广东省自然科学基金资助项目(2017B030306014)
广东省“珠江人才计划”引进创新创业团队资助项目(2016ZT06G025).
关键词
微合金化
桥壳钢
热模拟
大角度晶界
疲劳裂纹扩展速率
microalloying
bridge shell steel
thermal simulation
large angle grain boundary
fatigue crack growth rate
