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This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates (50 mm thick) by using finite element and contour measurement methods. A three-dimensional finite element model of 50-mmthick titanium component was proposed, in which a column-cone combined heat source model was used to simulate the temperature field and a thermo-elastic-plastic model to analyze residual stress in a weld joint based on ABAQUS software. Considering the uncertainty of welding simulation, the computation was calibrated by experimental data of contour measurement method. Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint. The peak tensile stress exceeds the yield strength of base materials inside weld, which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.

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Plates (37 mm thick) of 6005A-T6 aluminum alloy were butt joined by a single-sided and double-sided friction stir welding (FSW). The 3D residual stresses in the joints were determined using neutron diffraction. The microstructures were characterized by a transmission electron microscope (TEM) and electron backscatter diffraction (EBSD). In the single-sided FSW specimen, there were acceptable mechanical properties with a tensile strength of 74.4% of base metal (BM) and low residual stresses with peak magnitudes of approximately 37.5% yield strength of BM were achieved. The hardness is related to the grain size of the nugget zone (NZ), and in this study, precipitations were dissolved due to the high heat input. In the double-sided FSW specimen, there were good mechanical properties with a tensile strength of 80.8% of BM, but high residual stresses with peak magnitudes of approximately 70% yield strength of BM were obtained. The heat input by the second pass provided an aging environment for the first-pass weld zone where the dissolved phases were precipitated and residual stresses were relaxed.

The Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti17) titanium alloy is the main material used in manufacturing blades and disks of aero engines, and it is always jointed with different microstructures for the design constraints. In this work, the residual stresses of linear friction welding of β Ti17 and α + β Ti17 are measured by contour method and the X-ray diffraction method. The welding-induced tensions were found to be greater on the β side than that on the α + β side, and had an obvious reduction in the weld centre. After the post weld heat treatment (PWHT) of 630°C for 3 h, all tensions on the β side relax to a very limited value while some new PWHT-induced compressions are found on the α + β side.

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