Measurement and simulation of residual stresses in transient liquid phase bonded ferritic steels

Abstract

Ferritic steel bars -25 mm in diameterwere welded by transient liquid phase bonding (TLPB) using Fe-based amorphous metallic foils as filler material. The resulting residual stress (RS) field shows a low peak magnitudeof 147 MPaas measured by neutron diffraction.The most distinctive feature of TLPB is the heat input delivered simultaneously at the whole joint that allows much lower cooling rates compared with arc welding (AW).Therefore, the elapsed time between 800 and 500 ºC (t 8/5) was particularly long reaching 390 sec. As a result, a low RS peak magnitude (147 MPa) was obtained in the as-welded condition. This value is well below the RS peak magnitude obtained with AW which typically attain the yield strength of the base metal (276 MPa).The numerical simulation of RS at the welded bars was performed by a thermal and mechanical analysis. It shows that TLPB produced a large austenized region, low cooling rates and a remarkable t 8/5. Consequently, the large volume in which the heat input is delivered is the driving force to reduce RS peak magnitudes. From the mechanical analysis, it was found that the simulated RS were in good agreement with the measured RS. Therefore, the proposed numerical simulation model can be used to predict RS in TLPB weldments.