合金冷镦钢ML40Cr脱碳层影响因素分析及优化

Analysis and Optimization of Influencing Factors on Decarburization Layer of Alloy Cold Heading Steel ML40Cr

某公司采用120t BOF→LF→RH→180×180连铸→线材轧制工艺,ML40Cr冷镦钢盘条成功研发,并批量生产。下游冷镦紧固件类的客户在加工过程通常采用攻丝、调质等工序,材料表面脱碳将引起螺牙强度不足、冷镦开裂等缺陷,直接导致螺栓产品在后续使用过程存在“脱扣”的风险,造成产品不合格。高端客户对材料脱碳层要求比较高,单边脱碳层深度要求控制在盘条直径的1.0%以下,因此优化脱碳层深度对于提升公司ML40Cr产品档次,进入高端紧固件客户具有十分重要的意义。结合生产实际,对轧制过程中影响ML40Cr盘条脱碳层深度的原因进行分析与工艺优化。

A compary adopts the 120 ton BOF→LF→RH→180×180 continuous casting→wire rod rolling process,and the ML40Cr cold heading steel wire rod has been successfully developed and mass produced.Customers of downstream cold heading fasteners usually use tap⁃ping,quenching and tempering and other processes in the processing process.Decarburization of the material surface will cause defects such as insufficient strength of the screw teeth and cold heading cracking,which will directly lead to the risk of“tripping”of bolt products in the subsequent use process,resulting in unqualified products.High end customers have high requirements for material decarburization layer,and the depth of unilateral decarburization layer is required to be controlled below 1.0%of wire rod diameter.Therefore,optimizing the depth of decarburization layer is of great significance to improve the grade of ML40Cr products and enter high⁃end fastener customers.Based on the pro⁃duction practice,is optimized the reasons that affect the depth of decarburization layer of ML40Cr wire rod in the rolling process is analyzed and optimizes the process is optimized.