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利用扫描电镜观察了中强可焊AlZnMg合金焊接接头应力腐蚀断裂的特点。结果表明,应力腐蚀断裂的特点深受接头本身的抗应力腐蚀性能的高低和断裂位置的影响。抗应力腐蚀性能高的接头,主要在热影响区断裂,断口几乎是全由韧窝组成的韧性断裂;而抗应力腐蚀性能低的接头,主要在熔合线近傍断裂,断口全是沿晶的脆性断裂。抗应力腐蚀性能低的合金焊接后,在大气中长期存放沿熔合线发生的开裂,是由焊接应力引起的,断口是典型的脆性沿晶断裂。
Scanning electron microscope (SEM) was used to observe the characteristics of stress corrosion cracking of welded joints of medium strength solderable AlZnMg alloy. The results show that the characteristics of stress corrosion cracking are strongly influenced by the stress corrosion resistance and fracture location of the joint itself. The joint with high stress corrosion resistance mainly breaks in the heat-affected zone, and the fracture is almost the ductile fracture composed entirely of dimples. The joint with low stress corrosion resistance mainly breaks near the fusion line and the fracture is all along the brittleness fracture. After the alloy with low stress corrosion resistance is welded, the long-term storage of cracking along the fusion line in the atmosphere is caused by the welding stress, and the fracture is a typical brittle intergranular fracture.