Simulations in multipass welds using low transformation temperature filler material

Transient thermal and residual stress fields in flux-cored arc welds were examined using a finite element (FE) model. Experimental multipass welds were produced using both conventional and low transformation temperature (LTT) filler metals. Temperature-dependent material properties and both convective and radiant heat loss boundary condition have been considered in the FE model. The effects of the transformation temperature and interpass intervals on residual stresses were examined. It was found that compressive longitudinal residual stresses were developed at the weld centreline in the LTT filler metal. A short-time interpass interval causes the weld fusion zone to be above the martensite start temperature allowing the optimal use of the phase transformation effect. The FE model is sensitive to alteration in welding parameters and can satisfactorily predict the residual stress distribution in welded parts.