2004 年 22 巻 1 号 p. 101-106
Welding filler metals that phase-transformation temperature is low have been developed recently at NIMS. In order to improve the reliability of welded joints by reducing welding residual stress, the developed welding filler metals are used. It is difficult to detect phase-transformation temperature (Ms : starting temperature of phase-transformation or Mf : finishing temperature of phase-transformation) of filler metals with low phase-transformation temperature by using Formaster because of the lack of its cooling power. As transformation behavior of filler metals to be used in welding is considerably different from that of single filler used with low phase-transformation temperature owing to dilution of the base metal, it should be detected at actual welding because it remains no more than speculation.
The authors detected the phase-transformation behavior during cooling process in welding by using the laser speckle strain measurement. As base materials, 9% Ni steel and low carbon steel plates were used for the experiments. On the other hand, several kinds of filler metals with low phase-transformation temperature were supplied. The transformation range and expansion during phase-transformation were clearly detected even the range was near the room temperature.