Cleaning: 1. The workpiece and fixture before heat treatment shall remove oil, salt, paint and other foreign substance 2. The fixture was first used in the vacuum furnace, be in not less than the workpiece in advance required in addition to air purification treatment under vacuum Second, the furnace charging: 1. Easy deformation of the workpiece in the heat treatment process, and heat should be conducted on special fixture 2. The artifacts should be placed in the effective heating area Three, preheating: 1. For complex shape or cross section has changed dramatically larger artifacts, as well as the effective thickness should be preheated 2. The preheating method has: a preheat to 800 degrees Celsius, secondary preheat to 500 ~ 500 degrees and 550 degrees Celsius, a preheating temperature speed should be limited.