大型铝合金压铸模的性能均匀性与开裂机理

Uniformity of properties and cracking mechanism of large-scale aluminum alloy casting die

通过微观组织观察与力学性能检测,分别对热疲劳龟裂与早期整体开裂失效的大型铝压铸模进行了分析。结果表明:由碳化物偏聚引起的微观组织及性能的不均匀,是导致大型铝合金压铸模热疲劳龟裂的主要原因;模具心部因存在局部的粗晶组织使其韧性恶化,在薄弱位置处的微裂纹快速扩展为致命性贯穿裂纹导致其早期整体开裂。此外,模具微区硬度的离散度,能较好地反映模具微区组织性能的均匀性。

The thermal fatigue cracking and early gross cracking failure of large-scale aluminum alloy casting die were analyzed by microstructure and mechanical properties test. The results show that the uneven microstructure and properties caused by carbides segregation are the main cause of thermal fatigue cracking of large-scale aluminum alloy casting dies. The toughness of the casting die is deteriorated due to the existence of local coarse grain structure in the die core, and the microcracks at the weak position grow rapidly into fatal penetrating cracks and lead to its early gross cracking. In addition, the dispersion of die microhardness in micro-area can well reflect the uniformity of microstructure and properties of the die.