电子束焊铝合金微观结构对耐蚀性的影响

Relationship Between Microstructure and Corrosion Resistance of Al-alloy Joints in Electron Beam Welding

采用电子束焊接工艺焊接了一个铝制零件,用光学显微镜、SEM和EDS研究了其焊缝的微观组织和耐蚀性机理。结果表明,焊接接头没有形成热影响区,熔合区由致密细小的柱状晶组成。热影响区的缺乏和熔合区致密的晶粒结构提高了焊缝的防腐性。沿熔合区晶界分布的富Cu共晶组织也提高了其耐蚀性。

An aluminum alloy part was welded by electron beam welding process, and the microstructure and mechanism of corrosion resistance of the welded joint were investigated by optical microscope, SEM and EDX. The results show that there is no formation of the heated affected zone（HAZ） in the joint. The fusion zone（FZ） is composed of the compact fine columnar grains. Both the absence of the HAZ and compact grain structure of the FZ improve the corrosion resistance of the weld part. Moreover, the Cu-rich eutectic structure which distributes along the grain boundaries of the FZ also results in the improvement of the corrosion resistance.