420CL焊缝冷成形轮缘横裂分析及改进  

Analysis and improvement of FBW weld transverse crack of 420CL for rolling forming steel wheel rim

作　　者：张征 何先勇 赵光 ZHANG Zheng;HE Xian yong;ZHAO Guang(Tangshan Iron and Steel Group Co.,Ltd.Technology Center,Tangshan 063000 Hebei,china;Hebei High Quality Steel Continuous Casting Technology Innovation Center,Tangshan 063000 Hebei,china)

机构地区：[1]唐山钢铁集团有限责任公司技术中心,河北唐山063000 [2]河北省高品质钢连铸技术创新中心,河北唐山063000

出　　处：《四川冶金》2023年第3期39-43,共5页Sichuan Metallurgy

摘　　要：客户使用420CL热轧钢带制作轮辋过程中,在滚型、扩涨等冷成形工序轮辋轮缘出现与焊缝垂直方向的横裂纹,通过光学显微镜、扫描电镜、能谱仪检测等手段,对420CL钢热轧基板及轮辋开裂焊缝进行分析,确定导致焊缝开裂的原因。结果表明:焊缝接头部位为受热和力作用的固态相变组织,其会遗传母材基体的高强度,母材基体强度高,对应其焊缝强度高、硬度大,其焊缝与母材的硬度差异大,焊缝接头表层存在的粗晶粒区与细晶粒区的交界成为裂纹源,导致轮辋外表面塑性变形时协调变形的能力差。通过分析合金成分对性能的影响,优化成分设计,用Ti代Nb,降低材料的强度及屈强比,提高延伸率,改善420CL的综合力学性能,用其制作轮辋时开裂率约0.6%,完全满足下游客户的需求。In the process of using 420CL hot-rolled steel strip to make rims,transverse cracks perpendicular to the weld appeared in the rim flange of the cold forming process such as rolling and expansion.By means of optical microscope,scanning electron microscope and energy spectrometer,the cracking weld of 420 CL steel hot-rolled substrate and rim was analyzed to determine the cause of weld cracking.The results show that the weld joint is a solid phase change structure subjected to heat and force,which will inherit the high strength of the base metal matrix.The strength of the base metal matrix is high,and the corresponding weld strength is high and the hardness is large.The hardness difference between the weld and the base metal is large.The interface between the coarse grain zone and the fine grain zone on the surface of the weld joint becomes the crack source,resulting in poor ability to coordinate deformation when the outer surface of the rim is plastically deformed.By analyzing the influence of alloy composition on properties,the composition design was optimized,and Ti was used to replace Nb to reduce the strength and yield ratio of the material,increase the elongation,and improve the comprehensive mechanical properties of 420 CL.The cracking rate of the rim was about 0.6%,which fully met the needs of downstream customers.

关 键 词：420CL 轮辋 裂纹 硬度 成分 

分 类 号：TG142.41[一般工业技术—材料科学与工程]