HENRY GRANJON PRIZE COMPETITION 2007 Winner - Category C: "Design and Structural Integrity" CALCULATION OF THE EFFECT OF TRANSFORMATION EXPANSION ON WELD DISTORTION USING NUMERICAL ANALYSIS

A numerical simulation considering the transformation effect was applied to the evaluation of the relationship between the martensitic transformation expansion of weld metal and weld distortion of fillet-welded joints. Fillet T-joints were fabricated in order to measure weld distortion and model material properties for numerical simulation. The measured results of weld distortion showed that the weld angular distortion was reduced when low-transformation-temperature welding wire, of which transformation temperature is lower than conventional welding wires, was used. The numerical simulation, considering phase transformation effect, precisely reproduced the measured angular distortion behaviour. The numerical simulation method was applied to the evaluation of the effect of transformation expansion of weld metals on weld distortions of weld joints. The martensitic transformation start or finish temperature was varied in order to clarify the effect of the transformation temperature on weld distortions. Consequently, it was demonstrated that the martensitic transformation start temperature is most effective for reducing weld angular distortion.