Effect of Vacuum Electron Beam Welding Parameters on Microstructure and Properties of 304 Stainless Steel/CuCrZr Alloy Joint

CuCrZr alloy and 304 stainless steel were joined by normal and scanning vacuum electron beam welding. The effects of welding speed （10, 20, 30 mm·s⁻¹ with matching welding beam current of 18, 25, 36 mA）, scanning amplitude （0.5, 1.0, 1.5 mm）and the distance of electron beam offset to CuCrZr alloy side （electron beam offset, 0.2, 0.4, 0.6 mm） on the microstructure and mechanical properties of the joint were studied. The results show that when the electron beam offset was 0 and there was no scanning, cracks existed in the weld under different welding speeds. With the increase of welding speed, the cracks became more obvious, and the tensile strength and percentage elongation after fracture of the joint decreased. The welded joint under a welding speed of 10 mm·s⁻¹ had tensile strength of 385 MPa and percentage elongation after fracture of 4.56%. When the electron beam offset was 0 and the welding speed was 10 mm·s⁻¹, cracks existed in the weld under different scanning amplitudes. With the increase of scanning amplitude, the depression formed at the weld near CuCrZr alloy side became more obvious, and the tensile properties of the joint decreased; under the scanning amplitude of 0.5 mm, the tensile strength of the joint was 350 MPa, and the percentage elongation after fracture was 2.37%. When the electron beam offset was zero, the scanning amplitude was fixed at 0.5 mm, and the welding speed increased to 20, 30 mm·s⁻¹, no cracks were found in the weld, and the maximum tensile strength and percentage elongation after fracture of the joint reached 364 MPa and 5.40%, respectively. When the welding speed was 10 mm·s⁻¹ and there was no scanning, no cracks appeared in the weld under different electron beam offsets. When the electron beam offset was 0.2 mm, the weld microstructure was uniformly mixed, the tensile strength of the joint reached 324 MPa, and the percentage elongation after fracture was 5.51%. With the increase of the electron beam offset, the content of copper phase in the weld increased, and the tensile properties of the joint decreased.