Toward an Improved Understanding of Effect of Linear Heat Input on Heat-Affected Zone Tempering in Temper Bead Welding

In temper bead welding, the heat input from welding is purposefully utilized to temper the hard microstructure for improving toughness. An optimal temper bead welding requires careful control of heat input and bead placement. In this study, the effect of linear heat input on heat-affected zone (HAZ) tempering was studied by a combination of experimental testing and numerical modeling. Temper bead welding experiments were performed on SA-533 steel using three different heat inputs while keeping the power ratio constant. The extent of tempering in the HAZ was quantified using micro-hardness mapping. A 2-D weld heat transfer model, using the double-ellipsoidal heat flux equation, was developed to calculate the temperature evolution. The peak temperatures experienced in the substrate’s HAZ was correlated to the hardness distribution. The results indicate that the linear heat input can have a significant influence on the extent of tempering in temper bead welding.