Influence of local heat treatment on residual stresses in electron beam welding

Electron beam welding (EBW), as a high performance welding method, is also subject to requirements of high integrity welds which particularly include residual stresses affecting distortion and fatigue behaviour. In this context multiple beam technique may provide new applications of specific thermal weld treatment. The present work introduces a promising method of local post-heating in a certain distance to the current welding location applying multiple beams for the reduction in residual stresses in EB welded sheet metals. The conducted investigations include finite element analysis (FEA) and stress measurements in the weld seam area. Using a systematic approach within the FEA decisive process parameters are optimised with reference to the achievable reduction in residual stress. All simulation results are validated by experiments applying strain gauges for the stress measurement. Both simulations and experiments revealed a considerable decrease in residual stress achievable by appropriate positioning of additional heat sources combined with the right power input and beam focusing.