35MnBH链轨节余温淬火开裂成因及措施  

Causes and measures of residual temperature quenching crack of 35MnBH chain track link

作　　者：范芳东 Fan Fangdong(Fujian Sansteel(Group)Co.,Ltd.,Sanming 365000,China)

机构地区：[1]福建省三钢(集团)有限责任公司,福建三明365000

出　　处：《金属制品》2025年第2期24-28,共5页Metal Products

摘　　要：钢厂首次采用大方坯在中大棒生产线轧制59 mm 35MnBH圆棒,用户在生产链轨节后应用原余温淬火工艺时出现23.7%的开裂率。通过系统性试验分析失效机理并提出工艺优化方案。通过宏观形貌观察与金相分析,确认裂纹性质为淬火开裂。进一步对圆棒横截面化学成分、非金属夹杂物、力学性能及末端淬透性进行综合检测,发现横截面存在显著的化学成分偏析,近表面C、Mn含量高于心部区域,导致淬火过程中表层与心部马氏体相变行为差异,引发组织应力集中。末端淬透性试验表明,材料淬透性J13为45.8,超过技术指标。将原余温淬火温度从860~880℃降低至830~850℃,淬火开裂率控制在0.5%以内,符合用户要求。The crack rate of diameter 59 mm 35MnBH round rod rolled by large square billet in medium and large rod production line was 23.7%when customer applied original residual temperature quenching process after producing chain track link.Failure mechanism was analyzed by systematic test and process optimization scheme was proposed.Through macroscopic morphology observation and microstructure analysis,it is confirmed that crack is quenching cracking.The chemical composition,non-metallic inclusions,mechanical properties and end hardenability of cross section of round rod are further tested.It is found that there is significant chemical composition segregation in the cross section,and content of C and Mn near surface is higher than that core area,which leads to difference in martensitic transformation behavior between surface and core area during quenching,resulting in concentration of stress in structure.The end hardenability test shows that hardenability J13 of the material is 45.8,which exceeds technical index.Original residual temperature quenching temperature is reduced from 860~880℃to 830~850℃,quenching cracking rate is controlled within 0.5%,which meets the requirements of customers.

关 键 词：35MnBH 化学成分 余温淬火 淬透性 非金属夹杂物 

分 类 号：TG356.45[金属学及工艺—金属压力加工]