TWI Industrial Member Report Summary 362/1988
By C S Punshon and B G I Dance
Background
In-vacuum electron beam welding is being used increasingly as an alternative welding process in the heavy fabrication industries where there is a growing demand for improved productivity and weld quality. When conducting circumferential welds, however, some difficulties still exist in terminating welds in thick steel using a beam current fade-out technique, due to the formation of porosity defects and occasionally solidification cracking. The main objectives of the work reported here, which covers part of a continuing research programme, are:
1. To identify some of the factors responsible for fade-out problems, and
2. To develop techniques for improving fadeout quality.
Constant current partial penetration (CCPP) welds and fade-out tests were conducted in 70mm thick C-Mn steel, and the effects of various process variables on weld quality were isolated. Methods were developed by which satisfactory fade-out integrity could be achieved, for this material and thickness.