X80钢铜衬垫自动焊外根焊接头的组织与性能

Microstructure and Properties of X80 Steel Joint by Copper Liner Automatic External Root Welding

采用铜衬垫自动焊外根焊工艺对X80钢进行焊接,研究了焊缝成形质量以及粘铜区域和未粘铜区域的铜含量、显微组织及力学性能。结果表明:焊缝成形良好,未发现裂纹、未熔合等缺陷。未粘铜区域的铜含量与母材一致,粘铜区域的铜质量分数约为0.46%,渗铜深度约为0.18 mm;未粘铜区域焊缝组织主要由针状铁素体和少量的先共析铁素体组成,粘铜区域则主要是块状铁素体、粒状贝氏体以及游离铜组成。未粘铜区域和粘铜区域硬度变化趋势基本一致,焊缝根部粘铜区域的硬度略高于未粘铜区域;粘铜区域和未粘铜区域的抗拉强度分别为730,732 MPa,冲击性能基本一致,弯曲试验后均未见裂纹。焊缝根部渗铜未对接头的力学性能产生明显影响。

X80 steel was welded by copper liner automatic external root welding.The quality of weld formation and the copper content,microstructure and mechanical properties of the copper bonded and non-copper bonded areas were studied.The results show that the weld was well formed and no defects such as cracks or incomplete fusion were found.The copper content in the non-copper bonded area was consistent with the base metal.The copper mass fraction of the copper bonded area was about 0.46%,and the copper infiltration depth was about 0.18 mm.The microstructure of the weld in the non-copper bonded area was mainly composed of acicular ferrite and a small amount of pre-eutectoid ferrite,while that of the copper bonded area was mainly composed of block ferrite,granular bainite,and free copper.The hardness variation trend of the non-copper bonded area and the copper bonded area was basically the same.The hardness of the copper bonded area of weld root was slightly higher than that of the non-copper bonded area.The tensile strength of the copper bonded area and the non-copper bonded area was 730,732 MPa,respectively.The impact properties of the two areas were basically the same,and no cracks were found after bending test.The copper infiltration at the root of the weld had no obvious effect on the mechanical properties of the joint.