厚板铜镍合金电子束焊的接头组织与力学性能

Microstructure and mechanical properties of thick Cu-Ni alloy welded joint by EBW

采用真空电子束焊接实现了船用厚板铜镍合金的优质可靠连接,焊后对接头组织、显微硬度、拉伸性能和冲击性能进行了测试研究。研究结果表明,焊缝为粗大的枝晶组织,热影响区为晶粒大小不等的孪晶组织,靠近焊缝处晶粒有异常长大;接头显微硬度最高值为HV0.2122,出现在热影响区;焊接接头最大抗拉强度达到342 MPa,与母材等强,拉伸试样均在母材断裂,拉伸断口分布大小不一的韧窝,呈明显的韧性断裂特性;焊缝最高冲击吸收功达到160 J,高于母材的,热影响区最低冲击吸收功121 J,略低于母材的。

This work was aiming at investigation on the microstructure and mechanical properties of Cu-Ni alloy joints by Electron Beam Welding(EBW) with no filler materials. The results indicated that the microstructure of the fusion zone(FZ) was composed of coarse pine-tree structure. The heat affected zone(HAZ) consisted of twin crystal with different size. The HAZ near FZ consisted of some abnormality bigger size grain. Micro-hardness values for HAZ were higher than that of FZ and base metal, and there were the peak values for the HAZ near the weld metal. The tensile strength of joint was almost equal to that of base metal, and the fracture locations of all the tensile specimens were in base metal, and it was well in accordance with the relationship between microstructure and mechanical properties of welded joints. The tensile fracture morphology of joint presented obviously the characteristic of ductile fracture, which was related to the bigger and deeper dimples distributed on the surface of joint. The HAZ toughness exhibited 121 J which was lower than that of the BM and FZ, and the highest impact toughness was achieved in FZ which was 160 J.