Cr12 mould steel forging operation points – heat treatment

In addition to the forging operation of high speed steel, Cr12 die steel should pay attention to the following items:
(1) type Cr12 steel due to exist, and there are a lot of hard carbide along grain boundary forging heating effect more significant, and the eutectic temperature is low, therefore, more easily than high speed steel produced in the process of forging overheating and burnt. For this reason, in the forging operation, the existing temperature rise should be reduced in time to reduce the force of the hammer or to stop for a while. After the billet is gradually changed to the normal forging temperature, the hammer force will be increased.
(2) the Cr12 steel often due to poor quality of the surface, upsetting side surface cracks easily, therefore, should be to “riveting dui”, make blank bulky at both ends and sunken into the middle, when the rough height nearly (or length) of 1.5 times the diameter, vertical upsetting, until the basic flat side (< 1.5 don’t need “rivet heading”).
(3) when the Cr12 steel punching hole is prone to crack, it is recommended that the hole should not be perforated, especially in diameter less than phi 50mm. For large hole, if you have to punch, punch to preheat to 200 ~ 300 ℃; The taper of the punch should not be too large, and when the double-sided punch hole, it should be heated immediately after finishing one side, and then the other side, because the temperature of the contact with the anvil will decrease, and the crack will be produced easily.
(4) the Cr12 steel mold piece forging and several pieces of a whole forging quality difference is more, larger cross section on forging mould though measures is difficult to achieve small mould quality level, in order to ensure the quality should be the single piece forging production.
(5) under the blank material with cold sawing advisable, due to keen blanking, end residual burrs, upsetting the end to fold, to pull long, folds produce craze, and the dimension of eager not easy also accurate.
The determination of the heating time of the Cr12 mold steel, the size of the working process in the forging process, the selection of the tonnage of the forging hammer, the cooling standard, the common defects and the prevention measures are the same as the high speed steel.