生产中常遇见一些较短的45钢结构件,要求两种硬度。如图所示的零件,要求头部(φ60mm处)硬度为HRC43～48,螺杆部分硬度为HRC32～33。按照常规方法,先将螺杆部分淬火、回火、符合技术要求后,再将头部淬火、低温回火。这种操作工艺不但经济效益低,而且质量不能保证,因为两种硬 Often encountered in the production of some short 45 steel structure, requiring two kinds of hardness. As shown in the figure, the head (φ60mm Department) hardness of HRC43 ~ 48, the screw part of the hardness of HRC32 ~ 33. In accordance with conventional methods, the first part of the screw quenching and tempering, in line with technical requirements, then the head quenching, tempering at low temperature. This operating process not only low economic efficiency, but the quality can not be guaranteed because of two hard