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前面研讨了热挤压模具的有效区域的不可逆组织变化与损伤积累,弄清了组织变化与损伤扩展之间的关系。由此得知,热挤压模具经过一定使用阶段后,伴随硬化相沿晶界分布,在离表面0.40～0.56mm深度处,产生具有粗大晶粒组织的间隙层,它促进疲劳裂纹的产生与扩展,间隙层内部的损伤积累,导致产生容易剥离的孤立宏观区域。
In the previous section, the irreversible tissue changes and damage accumulation in the effective area of the hot extrusion die were studied, and the relationship between the changes of the tissue and the extension of the damage was clarified. From this, it can be seen that, after a certain use stage of the hot extrusion die, along with the grain boundary distribution of the hardened phase, a gap layer having coarse grain structure is generated at a depth of 0.40-0.56 mm from the surface, which promotes the generation and propagation of fatigue cracks , The damage accumulated inside the gap layer accumulates, resulting in isolated macroscopic regions that are easily peeled off.