Cause analysis of Cr12Mov die steel cracking after heat treatment
Cr12Mov die steel is a high hardness cold work die steel, which is usually heat treated to about 60HRC, normally speaking, if the purity of the material is good enough, the detection standard, the possibility of fracture of the material after vacuum heat treatment is very low. So why do many customers often crack the materials they buy in whose home?
First of all, we need to be sure that many people say that the heat treatment hardness is too high to greatly improve the possibility of material cracking, in fact, there are many reasons for cracking, not to mention, from the performance of Cr12Mov die steel heat treatment to 60HRC is absolutely in line with the relevant technical reference.
First of all, the first reason is that the material is not the material, that is to say, the material that breaks on your hand may not be CR12MOV die steel at all, so it is very easy to cause the heat treatment process is not in line, resulting in the possibility of cracking the material.
The second point is about the more professional problem of vacuum heat treatment, that is to say, when the Cr12Mov die steel is cooling, it is fast cold below the Ms temperature, and the stress is too large, which leads to the cracking of the material.
The third point is more forced, that is, the plane size of the workpiece is too large, resulting in uneven heat treatment, or containing impurities, unqualified detection, or the cause of excessive concentration of stress in some places.
The fourth point we can imagine is the problem of vacuum heat treatment process, that is, the quenching heating temperature is too high, the grain is coarse, and the brittleness is large. Grain boundaries oxidize or melt during overfiring.
The fifth point is that some thermal treatment plants do not preheat the workpiece when the Cr12Mov die steel is heat treated, and the heating speed is too large to cause heating cracking, which is a problem of operation specifications.
The sixth point can be said to be the quality of the material, in general, if you buy some small factory materials, although the procurement cost of these materials is low, but its terrible is in poor organization, raw materials exist mesh eutectic carbide or spheroidizing annealing poor, or raw materials have microscopic cracks, the possibility of crack expansion and cracking during quenching.
The seventh point is to return to the problem of heat treatment process, that is, the lack of intermediate annealing before repeated quenching is also a major reason for the cracking of Cr12Mov die steel.
The eighth point is that the Cr12Mov die steel is not tempered in time after quenching.
In fact, to sum up, we can conclude that the possibility of cracking of Cr12Mov die steel is nothing more than three points: heat treatment process problems, material quality problems, and heat treatment operation specifications. Generally speaking
