大规格易淬火直用冷镦钢生产实践

PRODUCTION OF LARGE-SCALE EASY-TO-QUENCH STRAIGHT COLD HEADING STEEL

针对大规格SWRCH35K淬透性不足问题,优化其成分体系,降低Si含量,控制C、Mn含量,并添加Cr、B元素等措施来解决。通过提高钢水洁净度,采用合适过热度,并使用大口径铝碳质水口解决了连铸“套眼”问题,同时,通过控轧控冷,得到合适的铁素体比例以及细小且均匀的珠光体组织,抗拉强度高于原SWRCH35K,硬度值为83.5(HRB)。直接加工后经过调质处理,使其芯部和边部硬度均匀,硬度为31~32(HRC),有效地解决了大规格冷镦钢芯部“淬不透”的问题。

In response to the problem of insufficient hardenability of large-sized SWRCH35K,measures such as optimizing its composition system,reducing Si content,controlling C and Mn content,and adding Cr and B elements are adopted to solve the problem.By improving the cleanliness of molten steel,adopting appropriate superheat,and using aluminum carbon water nozzles,the problem of“sleeve hole”in continuous casting has been solved.At the same time,by controlling rolling and cooling,a suitable ferrite ratio and a small and uniform pearlite structure have been obtained.The tensile strength is higher than that of the original SWRCH35K,and the hardness value is 83.5(HRB).After direct processing,it undergoes quenching and tempering treatment to ensure uniform hardness of the core and edges,with a hardness of 31~32(HRC),effectively solving the problem of insufficient quenching in the core of large-sized cold heading steel.