晶粒组织对Al-Cu合金应力腐蚀开裂行为及导电率的影响

Effect of grain structure on stress corrosion cracking behavior and electric conductivity of Al-Cu alloy

通过研究和比较T3511态2224铝合金大尺寸Z字型断面不同位置的组织和应力腐蚀开裂行为,探讨了晶粒形态对抗应力腐蚀开裂能力和开裂方式的影响。结果表明,纤维状晶粒具有较低的应力腐蚀敏感性,在250 MPa应力下具有纤维状晶粒的试样52天断裂,而条状偏等轴晶粒试样的断裂时间仅为42天。条状偏等轴晶晶粒尺寸大且晶界为界面能较大的大角度晶界,晶界强度较低,应力腐蚀裂纹易沿着大角度晶界扩展。不同位置试样的开裂方式均为沿晶开裂,同时Z字型断面不同位置的导电率数值一直保持稳定。

Though investigating and comparing the microstructure and stress corrosion cracking(SCC)behaviors at different locations of large-size Z-shaped sections of 2224 aluminum alloy in T3511 state,the effects of grain morphology on the SCC resistance and cracking modes were discussed.The results show that the specimens with fibre-like grains have lower stress corrosion sensitivity and are fractured in 52 days at stress of 250 MPa,while the specimens with nearly equiaxed grains are fractured in only 42 days.The nearly equiaxed grains have larger grain size and large-angle grain boundaries with higher interfacial energy,along which the stress corrosion crack is easy to propagate due to the lower grain boundary strength.The cracking mode of the specimens at different positions is all intergranular cracking,and the conductivity value in different positions of the Z-shaped section remains stable.