Na,K杂质及微量Ce对8090合金裂纹扩展阻力的影响

EFFECT OF Na AND K IMPURITIES AND Ce MODIFICATION ON CRACK PROPAGATION RESISTANCE FOR ALLOY 8090

研究了含0.05%Ce及不同Na,K杂质含量的8090合金薄板裂纹扩展阻力,探讨了合金断裂韧性及裂纹起始扩展阻力随(Na+K)含量变化的规律和微量Ce的作用,结果指出:随(Na+K)含量增加,合金裂纹扩展阻力下降;若(Na+K)含量处于一定范围内时,合金中加入0.05%Ce会改善其断裂韧性及裂纹起始扩展抗力;当(Na+K)含量过高,Ce的这种有益作用便被掩盖,Na,K对合金韧性造成危害的原因之一是可以促使T_1等相沿晶界或亚晶界析出,并促使再结晶晶粒异常长大。

The crack propagation resistance for alloy 8090 sheet decreases with the increase of content of Na and K impurities. An improvement over the fracture toughness and crack initi- ation resistance for the alloy containing Na and K within certain limit may be made by adding 0.05% Ce. This beneficial modification would not be manifested if the alloy contained more enough Na and K. One of the reasons why Na and K injure the toughness of the alloy might be due to that they cause the precipitation of T_1 phase along grain and subgrain boundaries and accelerate the abnormal growth of recrystallized grains.