Abstract: A new low transformation temperature electrode-(LTTE) is developed based on the volume expansion principle that weld metal begins to transform from austenite to martensite at round 191 °C and finishes about room temperature. The weld metal of LTTE can obtain compressive residual stresses by phase stress at usual cool speed. These may enhance the fatigue strength of welded joints. The fatigue specimens of five kinds of the typical welded joints welded by LTTE and E5015 electrode are selected to conduct fatigue test. It is shown that the former fatigue strength is improved respectively from 11% to 58% than the latter at 2×106 cycles. It is also shown that the higher the stress concentration and restraint intensity of weld joints are，the higher their effect of improving fatigue strength are.

Key words: Compressive residual stress, Phase stress, Welded joints Fatigue strength