Heat treatment technology of cold working die steel
The main failure modes are overload failure, wear failure, failure and fatigue failure.
(1) the failed mold material itself is insufficient to bear the bearing capacity generated by the working load. When brittle fracture is not easy to occur, toughness and cracking are easy to occur, upsetting deformation and failure are easy to occur when strength is insufficient. Cold heading and cold extrusion die are prone to this failure.
(2) the friction loss between the working part of the mold and the material to be processed causes the shape and size of the working part (blade and punch) to change, leading to the failure. The size and quality of the working surface require high blanking die, extrusion die prone to this kind of failure.
(3) in the mold workplace and under the high pressure added to the friction material, the lubrication film breaks and occludes the processing material and "cold welding" it to the mold surface, causing scratches and failures on the surface quality of the processed products. In the drawing process, bending modulus and cold extrusion die are prone to such failure.
(4) the effect of cold die under impact load is at a certain speed and the effect of repeated energy, and its working state is similar to that of energy impact fatigue test. Due to the high hardness of the mold material, the fatigue life is more and more urgent, about 1000-5000 times, but the majority of the crack initiation, the source of the fatigue crack growth area is obvious. In large die, such as cold extrusion, cold heading die, multi - fatigue failure is common.