Influence of Melting Amount of TZM on the Microstructure and Properties of TZM/CoCrFeNiMo_0.2/Q235 Electron Beam Welded Joints

The influence of TZM melting amount on microstructure and mechanical properties of TZM/CoCrFeNiMo_0.2/Q235 electron beam welded joints was studied by using different interlayer thicknesses and beam offset distances. TZM molybdenum alloy and Q235 steel were joined using a CoCrFeNiMo_0.2 high-entropy alloy as an interlayer. The study demonstrated that optimal welding parameters, including an interlayer thickness of 0.4 mm and a beam offset distance of 0.2 mm, resulted in joints with superior tensile strength and defect-free weld morphology. Adjustments to interlayer thickness and beam positioning effectively controlled the melting extent of the TZM base material, thereby regulating the Mo content within the weld and suppressing the formation of brittle intermetallic compounds. Detailed microstructural analysis revealed that fine eutectic structures within the reaction layer played a crucial role in improving the performance of the joints, while excessive interlayer thickness or improper beam offset compromised mechanical integrity. These findings provided valuable insights into the development of high-performance composite structures and innovative welding strategies for dissimilar material joints.