我厂生产的150mm四用游标卡尺中的测尺如图1所示,材料为T8钢。热处理后要求:硬度尺身HRC43～53,测量面HRC≥58,前端面、尾端面HRC≥40。金相组织测量面马氏体级别不大于2.5级。原用传统工艺流程如下:整体淬火—清洗—中温回火(上夹具入炉)—外卡爪淬火—清洗—内卡爪淬火—低温回火—清洗。热处理工艺曲线如图2。淬火加热在盐浴炉内进行,中温回火在井式炉内进行,低温回火在硝盐槽内进行。为了避免热传导引起尺身硬 I produced the 150mm four vernier caliper ruler as shown in Figure 1, the material is T8 steel. After heat treatment requirements: hardness scale HRC43 ~ 53, measuring surface HRC ≥ 58, the front face, tail face HRC ≥ 40. Metallography measurement martensite level not more than 2.5. The original traditional process is as follows: Overall quenching - cleaning - tempering at medium temperature (on the fixture into the furnace) - the outer jaw quenching - cleaning - within the jaw quenching - tempering - cleaning. Heat treatment process curve shown in Figure 2. Quenching heated in a salt bath furnace, tempering temperature in the pit furnace, low temperature tempering in the salt tank. In order to avoid heat conduction caused by the ulnar stiff