TC4-DT钛合金电子束焊接接头的拉伸性能

Tensile Properties of Electron Beam Welded Thick TC4-DT Joint

摘要:

用电子束焊接50 mm厚TC4-DT钛合金板，对母材、焊缝金属和焊接接头的拉伸性能进行测试，获得了母材和焊缝金属的基本拉伸性能数据，分析了电子束焊接接头显微组织对拉伸性能的影响。结果表明，电子束焊接使TC4-DT钛合金焊缝金属强度增加，塑性和韧性降低，应变硬化能力增强。焊接接头拉伸试验的断裂位置均在离焊缝边缘较远的母材上，母材为整个接头的薄弱环节。母材和焊缝金属拉伸断口均表现出延性韧窝断裂特征。与母材金属相比, 焊缝金属拉伸性能的变化与电子束焊接过程中冷却速度快、在焊缝区形成了粗大β柱状晶及针状马氏体有关

Abstract:

A 50 mm thick TC4-DT alloy plate was welded using electron beam. Ultimate tensile tests of base metal, weld metal and the whole joint were carried out to collect the tensile property data. Moreover, microstructure and fracture morphology after tensile tests were observed to study the effect of electron beam welding on tensile properties of TC4-DT alloy. The results indicate that both the base metal and weld metal exhibit high strength and weak strain hardening ability. Electron beam welding makes the weld strength and strain hardening ability increase, while the plasticity and ductility decrease. Base metal is the weakest part of the whole joint, and the fracture occurs on the base metal away from the weld metal during the tensile tests of the joints. In addition, fractography of both the weld metal and base metal is found to be dimple, which means that the fracture feature of both the base and weld metal is ductile. The tensile property difference between the base metal and weld metal is related to the microstructure change of weld metal after welding. The increase of strength and decrease of plasticity and ductility for weld metal is mostly dependent on the formation of coarse β columnar grain and martensite in the weld metal due to the very fast cooling speed during electron beam welding