合金冷镦钢SCM435冷镦开裂原因分析  

Cause Analysis of Cold Heading Cracking of Alloy Cold Heading Steel SCM435

作　　者：刘荣泉 郑福胜 靳君 Liu Rongquan;Zheng Fusheng;Jin Jun(Chief Engineer Office,Changshu Longteng Special Steel Group Limited Company,Suzhou 215511,China)

机构地区：[1]常熟市龙腾特种钢有限公司总工办,苏州215511

出　　处：《特殊钢》2025年第2期116-120,共5页Special Steel

摘　　要：某汽车配件生产商使用规格ϕ24 mm的合金冷镦钢SCM435热轧盘条,开发某款形变量接近90%的中轴类产品。原材料经“2拉2球”工艺拉拔后,在冷镦加工时出现批量开裂,开裂比例约60%。经对开裂产品进行理化检测分析。分析结果表明,冷镦开裂问题源于材料塑性不足导致的应力开裂。进一步检测发现,用户球化退火热处理工艺不良,球化组织仅有4.0级,是导致材料塑性和韧性不足的根本原因。通过优化球化热处理工艺,将球化退火加热段温度由765℃降至745℃,使材料球化组织级别达到5.0~6.0级,有效改善了材料的塑性和韧性,成功解决了产品在冷镦过程中出现开裂的质量问题。A certain auto parts manufacturer uses alloy cold heading steel SCM435 hot-rolled wire rod with a specification of Φ24 mm to develop a mid-shaft product with a deformation rate approaching 90%.After the raw materials were drawn through a"2-draw-2-ball"process,a batch of cracks appeared during cold heading processing,with a cracking ratio of about 60%.Physical and chemical testing and analysis were conducted on the cracked products.The analysis results indicated that the cold heading cracking issue originated from insufficient material plasticity leading to stress cracking.Further inspection revealed that the user's spheroidizing annealing heat treatment process was poor,with a spheroidization structure only at grade 4.0,which was the fundamental cause of the insufficient material plasticity and toughness.By optimizing the spheroidizing heat treatment process,the spheroidizing annealing heating section temperature was reduced from 765℃to 745℃,bringing the material spheroidization structure grade to 5.0-6.0,effectively improving the materialrs plasticity and toughness,and successfully solving the quality issue of cracking during the cold heading process of the product.

关 键 词：SCM435冷镦钢 冷镦开裂 应力裂纹 球化退火 

分 类 号：TG142.15[一般工业技术—材料科学与工程]