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对30 mm厚TC4钛合金进行电子束焊接试验,通过金相分析以及显微硬度测试对焊接接头的显微组织和力学性能进行了研究。结果表明,TC4钛合金母材由等轴α以及部分β转变组织组成,焊缝区组织在纵向上具有不均匀性。焊缝顶部β柱状晶粗大,沿熔合线向顶部生长,中部和下部柱状晶相对较小,垂直熔合线向焊缝中心对称竞相生长。β晶粒内部微观组织为针状马氏体,马氏体尺寸从焊缝顶部到底部逐渐减小。热影响区显微组织为等轴初生α相和α’针状马氏体,以及未完全转变的β相。焊缝区和热影响区显微硬度值高于母材;在焊缝区纵向上,顶部显微硬度值为340 HV,随着距离焊缝顶部距离的增加,硬度值显著增大,最大值为435 HV。
Electron beam welding of 30 mm thick TC4 titanium alloy was carried out. The microstructure and mechanical properties of the welded joint were studied by metallographic analysis and microhardness test. The results show that the base metal of TC4 titanium alloy is composed of equiaxed α and partial β transformation, and the microstructure of weld zone is inhomogeneous in the longitudinal direction. The β-columnar crystals at the top of the weld are coarse, grow to the top along the weld line, the middle and lower columnar crystals are relatively small, and the vertical weld line grows symmetrically to the center of the weld. The microstructure of β grains is acicular martensite, and the martensite size decreases gradually from the top to the bottom of the weld. The HAZ microstructure is equiaxed primary α and α ’acicular martensite, and incompletely transformed β phase. The microhardness value of the weld zone and the heat affected zone is higher than that of the base metal. In the longitudinal direction of the weld zone, the microhardness value of the top is 340 HV. The hardness value increases significantly with the distance from the top of the weld seam, It is 435 HV.