Mould vacuum heat treatment

The vacuum heat treatment of mould includes preparation heat treatment, final heat treatment and surface strengthening. Usually refers to die in the final heat treatment defect or in the future in the process of heat treatment process and all kinds of defects in the process of using, such as quenching crack and deformation out-of-tolerance, hardness and electric processing and cracking, grinding cracks, die early damage, etc. Let’s do a more detailed analysis.
One, cracking. The causes and preventive measures of quenching are as follows:

1. The shape effect is mainly caused by design factors, such as the small rounded Angle R, improper location of the hole, and poor cross section.
2. Overheating (overheat) is mainly caused by temperature control or running temperature, vacuum heat treatment process, unreasonable, unreasonable, and especially inadequate tempering. The setting of temperature is too high and the temperature of the furnace is not equal. The preventive measures include repairing and checking the control temperature system, modifying the process temperature and adding the iron between the workpiece and the floor of the furnace.
3, decarburization, mainly by overheating or burnt, unprotected air furnace heating, small machining allowance, forging or prepare to factors such as heat treatment residual decarburized layer, the preventive measures for the controlled atmosphere heat, salt bath heating, vacuum furnace, box-type furnace adopts packing protection or use the anti-oxidation coatings; The machining allowance is increased by 2 ~ 3mm.
4. Improper cooling is mainly caused by the selection of coolant or too cold, and the cooling characteristics of quenching medium or tempering treatment should be mastered.
5, organization of raw materials, such as carbide segregation, forging quality is poor, prepare the improper heat treatment methods, such as preventive measures is to use the correct forging process and reasonable heat treatment system.