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In the production of die forgings, such as ingots or steel residual shrinkage, air bubbles, loose, inclusion, etc., may lead to forging cracking; And even if only the raw material surface scratch, scarring, folding, cracking, will also bring defects to the forgings. Therefore, raw materials must be inspected in the production of die forgings.
When forging large die forgings and alloy steel die forgings, if the heating rate is too fast, the temperature difference between the inner and outer layers is large, and the temperature stress and microstructure stress will lead to the crack in the center part. However, if the heating temperature is too high and the holding time is too long, the coarse grain fracture with luster, crystallinity and intergranular fracture will be produced. So we must control the heating specification, in order to refine the grain, improve the structure, improve the mechanical properties, for steel with such a structure, must be fully annealed to produce recrystallization.
In addition, by applying different thermal and mechanical conditions to the blank under different die forging deformation modes, the blank will have different physical fields and the evolution process of microstructure and properties. Therefore, the die forging process of the same die forging will change its quality.
In addition, the quality of die forgings is also related to the design of forgings and die. The choice of machining allowance and forging tolerance should be based on reality. The die parting surface of the forgings, the belly of the die forging, the radius of the fillet, the size of the skin and the structure of the flaps should also be designed in accordance with the reality. In short, every link in the production of die forgings will have a significant impact on the quality of forgings.
