Abstract The bead geometry of autogenous bead-on-plate tungsten inert gas (TIG) welding performed on Ti-6Al-4 V alloy inside an argon inert box chamber was measured for different processing conditions. The microstructural evolution of the weldment was evaluated through optical microscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD) technique. The development of residual stress and the texture in the weldment were assessed through the XRD techniques. The full penetration melting for bead-on-plate welding was obtained for high current and low scan speed combination that induces maximum heat input within the experimental domain. Owing to intense heat of the TIG arc, a complex microstructural evolution occurred in the Ti-6Al-4 V alloy, which causes transformation of initial β phase to martensitic α’ phases. The transformation of initial α + β phase to martensitic α’ phase enhances the hardness value of the melt pool upto 365 HV0.2, and further at heat affected zone (upto 385 HV0.2) owing to grain refinement. The residual stress developed in the weld melt pool was recorded tensile type, and for increasing the welding current, due to the enhancement of induced heat, the residual stress increased from 140 to 200 MPa (for 80 A) to 240–270 MPa (for 100 A).

中文翻译：

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Ti-6Al-4V合金板珠TIG焊组织演变及金相特性

摘要 测量了在氩气惰性箱室内对 Ti-6Al-4 V 合金进行自生板载钨惰性气体 (TIG) 焊在不同工艺条件下的焊道几何形状。通过光学显微镜、扫描电子显微镜 (SEM)、X 射线衍射 (XRD) 技术评估焊件的微观结构演变。通过 XRD 技术评估焊件中残余应力的发展和织构。在高电流和低扫描速度的组合下，在实验范围内引起最大热输入，获得了板珠焊接的全熔透熔化。由于TIG电弧的强烈热量，Ti-6Al-4V合金发生了复杂的微观结构演变，导致初始β相转变为马氏体α'相。初始α+β相向马氏体α'相的转变使熔池的硬度值提高到365 HV0.2，并且由于晶粒细化而在热影响区进一步提高（高达385 HV0.2）。焊缝熔池中产生的残余应力记录为拉伸型，随着焊接电流的增加，由于感应热的增强，残余应力从 140 到 200 MPa（对于 80 A）增加到 240-270 MPa（对于100 A)。