Effect of characteristics of transformation expansion of weld metals on angular distortion behavior of welded joints - Welding angular distortion control by transformation expansion of weld metals (Report 2)

The effect of martensitic transformation start temperature and transformation expansion strain on welding angular distortion of welded joints was investigated. T-joints were fabricated with welding wires of which Ni and Cr content were varied and the residual angular distortion of the T-joints was measured. The residual angular distortion decreased when the martensitic transformation start temperature increased in the range from 100°C to 405°C. A numerical simulation with consideration of the effect of phase transformation was performed to investigate the relationship between the transformation expansion of the weld metal and the angular distortion of a T-joint. In order to clarify the effect of the transformation temperature and the transformation expansion strain separately, numerical simulations were carried out with hypothetical properties of transformation expansion. Evaluated were the relationship between the reduction of the angular distortion by the transformation expansion of the weld metal and properties of transformation expansion: transformation start temperature and transformation expansion strain. The reduction increased when the transformation temperature increased under hypothetical conditions that the constant transformation expansion occurred regardless of transformation temperatures. It also increased when the transformation expansion strain increased. In actual materials, as the transformation expansion strain is dependent on the transformation temperature, an optimum temperature range for reducing angular distortion exists.