Effect of Transformation Temperature on Improving the Fatigue Strength of Welded Joints

The phase stresses produced by transformation expansion strain at different transformation temperature can affect the kinds and values of the residual stresses of welded joints. The effect of transformation temperature of weld metal on the residual stresses and the fatigue strength of welded joints is analyzed based on their test. The fatigue specimens of welded joints with longitudinal stiffeners welded by five welding electrodes whose transformation temperatures of deposited metal are different, are selected to conduct fatigue test, which have high restraint intensity and stress concentration. It is shown that the fatigue strength of welded joint is the highest in all welded joints at around 191℃ of transformation temperature. It is also shown that the welding electrodes with low transformation temperature can improve the fatigue strength of welded joints.