SWRCH35K冷镦钢球化退火工艺

Spheroidizing annealing of SWRCH35K cold heading steel

在双相区+亚温区球化退火的基础上,对SWRCH35K冷镦钢进行球化退火试验。由SWRCH35K冷镦钢的化学成分通过Thermo-calc软件计算得到试验钢的A1点为719℃,A3点为792℃。在综合分析影响球化的因素的基础上,重点考虑加热温度、加热时间、等温温度、等温时间4个因素的影响,确定了它们的试验设定值,并依此设计出试验方案。由试验结果可知:在加热温度为730℃,加热时间为30 min,等温温度为700℃,等温时间为6 h的情况下,碳化物颗粒尺寸适中、数量较多且分布弥散,获得了最好的球化效果。且整个球化周期约为8 h,与一般的球化工艺相比,周期明显缩短。且加热温度和等温温度值的选取,可以为在线球化退火工艺的制定提供参考。

Based on the intercritical ＆ subcritical spheroidizing annealing, some experimental works were done on SWRCH35K cold heading steel. The temperatures of critical points A1 and A3 for SWRCH35K cold heading steel were calculated to be 719 ℃ and 792℃, respectively, by using Thermo-calc software. On basis of comprehensive analysis on the factors which influence spheroidizing, with consideration of the influence of heating temperature, heating time, isothermal temperature and isothermal time, their experimental values and the scheme were designed. The experimental results show that under the condition of the heating temperature at 730 ℃, heating time for 30 min, isothermal temperature at 700 ℃, isothermal time for 6 h, the carbide size is moderate, the amount of carbide is large, carbides distribute dispersively, and the best effect of spheroiddizing can be obtained. The whole spheroidizing period is about 8 h, compared with the conventional spheroidizing process, the spheroidizing period is obviously reduced. The selection of heating temperature and isothermal temperature can provide reference for online spheroidizing annealing process.