B_4C对MGH956合金TIG焊接头性能的影响

Effect of B_4C on Mechanical Property of TIG Weld Joint of an ODS High Temperature Alloy MGH956

采用TIG焊对MGH956合金进行原位合金化焊接,研究了B4C对焊缝显微组织和力学性能的影响。结果表明,填加B4C后焊缝以等轴晶为主,晶粒细小均匀,没有明显的氧化物聚集现象,晶内和晶界都有增强相;随着B4C含量的提高焊缝组织进一步细化,增强相几乎全部集中在晶界上,晶内颗粒状增强相消失。随着B4C含量的提高焊缝的塑韧性降低,抗拉强度先增大后降低。填加0.25%B4C时焊缝抗拉强度最高,达到630 MPa,为母材强度的87.5%,断口呈脆性断裂。

The 1.3 mm thick plate of ODS high temperature alloy MGH956 was TIG welded with fill- ers containing different B4C （0, 0.25 and 0.5 mass %）, then the effect of B4C content on the microstructure and mechanical properties of the weld joints was investigated. The results show that the microstructure of the weld metal with B,C exhibits mainly equiaxed grains, which are fine and uniform, without significant agglomeration of oxide dispersoids, while the strengthening particulates of the alloy distribute in both grains and grain boundaries. The microstructure of weld joint was finer as the filler with B4C content in a range from 0.25 to 0.5 mass%. However nearly almost the strengthening particulates of the alloy concen- trate in the grain boundaries but disappear in the grains for the weld joints by filler with 0.5% B4C. The ten- sile strength of the weld joints firstly increases and then decreases when the B4C content of the fillers ranged from 0% to 0.5 mass%, but their toughness decreases with the induce of B4C. The tensile strength of the weld joint with filler material containing 0.25% B4C is the highest i.e. 630 MPa, reaching 87.5% of the parent material. The fractured surface exhibited characteristics of brittle fracture.