XRDおよびEBSDを用いた23Cr-45Ni-7W合金溶接部のひずみ評価

Abstract

The residual strain of 23Cr-45Ni-7W Alloy welds was estimated by the change in the dislocation density and the average misorientation within grains. X-ray diffraction was used to measure the dislocation density by the modified Williamson-Hall method and the modified Warren-Averbach method. EBSD technique was used to measure the orientation in order to calculate the grain orientation spread (GOS) as the average misorientation within grains. Tensile tests were conducted at room temperature and were interrupted to prepare a number of specimens with different residual strain. The changes in the dislocation density and GOS with the strain were investigated using the interrupted specimens and the heat-affected zone in 23Cr-45Ni-7W Alloy welds. The dislocation density and GOS increased approximately linearly with increase in the residual strain. The residual strain of the heat-affected zone in 23Cr-45Ni-7W Alloy welds was evaluated from the linear relationships. The residual strain near the bond line estimated by the dislocation density was 3.7%;the estimated residual strain decreased with increases in the distance from the bond line. At 10 mm away from the bond line, the residual strain became less than 1%. The change in the residual strain near the bond line estimated by GOS showed a similar tendency.