汽车紧固件用冷镦线材的现状

Present situation of cold heading wire rod for automobile fastener

介绍汽车零部件用线材的数量、品种,以及汽车紧固件的生产状况和市场需求。指出国内冷镦线材现状:标准可选用范围狭窄,冷镦线材品种数量较少;原材料存在冷镦开裂,有的开裂率超过10%;线材中各元素成分不仅要符合标准规定,还应对S,P含量严格控制,并对C,S i,Mn的组合比例分组优化;紧固件企业一般对产品的后处理(冷镦后调质、渗碳处理)较为重视,对冷镦前处理不重视,专业线材厂采用SCT炉、井式炉、抽真空加氮基保护气氛炉的较普遍,而使用氢气保护的钟罩炉球化退火较少,使紧固件质量受到很大影响。针对国内已经具备制造汽车紧固件优质线材的基本条件,建议尽快采用专坯专用,建立加强质量管理的冷镦线材供应链,逐步缩小与发达国家的差距。

To introduce the quantity, variety of wire rod for automobile parts and the manufacture of automobile fastener and market requirement. The present situation of China cold heading wire rod is pointed out. The scope can be selected in standard is narrow. The variety and quantity are little. Cold heading cracking exists in raw material, the cracking rate of some is more than 10%. Each element composition in wire rod reaches requirements of standard, the content of S, P is controlled strictly, and the combination ratio of C, Si, Mn is optimized in group. Fastener factory usually paid more attention to post treatment such as hardening and tempering after cold heading, carburization treatment of products, paid little attention to cold heading pretreatment. It is usual to adopt SCT furnace, well - type furnace, vacuum pumping and adding ni- trogen -based protective atmosphere furnace in special wire rod factory, but few adopt hydric protective bell-type furnace spberoidization annealing, which has great impact on the quality of fastener. Aiming at the facts that China has the ability to produce quality wire rod for automobile fastener, it is suggested to adopt special billet special purpose, to establish cold head- ing wire rod supply chain which strengthens quality management, to reduce the difference with advanced country slowly.