Everyone knows that stainless steel screws now require molds for stainless steel screws during cold forming. In the process of producing stainless steel fasteners, the molds are subjected to impact loads. In order to reduce the damage in the form of breakage, chipping, etc. during use, the mold steel is required to have a certain degree of toughness.
The chemical composition, grain size, purity, carbides, inclusions, etc., number, morphology, size, and distribution of the die steel, and the heat treatment system of the die steel and the metallurgical structure obtained after the heat treatment are all of the steel. The toughness has a big impact. In particular, the degree of cleanliness of the steel and the distortion of the hot working have a more pronounced effect on its transverse toughness. The toughness, strength and wear resistance of steel are often conflicting. Therefore, we must reasonably choose the chemical composition of the steel and use reasonable refining, thermal processing and heat treatment processes so that the wear resistance, strength, and toughness of the mold material are optimally matched.
Impact toughness is the total amount of energy absorbed by the sample during the entire fracture process during a single impact. However, many tools are fatigue fractured under different working conditions. Therefore, conventional impact toughness cannot fully reflect the fracture properties of die steel. Test techniques such as multiple energy impact fracture work or multiple fracture life and fatigue life are being used.
The above shows the importance of the mold when cold-tapping stainless steel screws or cold-extruded stainless steel fasteners.