Effect of Tungsten Electrode Eccentricity on Microstructure and Properties of TC4 Welded Joints in Rotary Tungsten Inert Gas Welding

Experiments were conducted to investigate the microstructure and properties of Ti‐6Al‐4V rotational arc welded joints using tungsten electrodes with varying eccentricities. The arc's rotation during welding expanded the heated area around the groove, increasing the heat‐affected zone (HAZ) width. The weld zone primarily consists of lath martensite. Increasing electrode eccentricity reduces low‐angle grain boundaries and causes a nonlinear change in grain size. At 0.75 mm eccentricity, the average grain size reaches a minimum of 0.72 μm. The dislocation angle range for the α phase in the weld zone is 1.05°–4.35°, 55.6°–65.3°, and 88.3°–90.45°. Static tensile strength values for the HAZ and weld zones exceed the base metal by over 97% (940 MPa), with elongation after fracture reaching 80% (11.14%) of the base metal's value. Impact toughness also surpasses over 80% (490.25 KJ m −2 ). Furthermore, at 0.75 mm eccentricity, impact toughness increases by more than 10% compared to other eccentricities, emphasizing the strengthening effect of fine grains on material impact toughness.