Interface formation and defect elimination mechanism of T2/304L interface during electromagnetic pulse welding process

Abstract

Experimental and numerical methods are carried out to analyze the interface formation and defect elimination mechanism during electromagnetic pulse welding T2 to 304L tube by changing the inner tube morphology from original scheme to stage scheme, ramp stage, and location stage. When the original scheme is operated with 13mm lap length, the morphology of interface is divided into four zones containing end unwelded zone, first welded zone, central unwelded zone, and second welded zone due to the different impact velocity and angle during the initial impact process, parallel impact process, and final impact process. The parallel impact leads to the formation of the central unwelded zone, containing (Cu, Fe) solid solution, oxides, nano grains, and amorphous phase. By providing a suitable impact angle, the ramp scheme (α = 7°) and location scheme (L = 6.5 mm) can eliminate the defect in the central unwelded zone.