Abstract
The distribution of toughness in HAZ of multi-pass welded high strength steel was investigated on the basis of the distribution of microstructure which had been discussed in the previous report.
The main results obtained were as follows.
(1) The toughness differed with each microstructure which had been classified in the previous report.
(2) The toughness of each microstructure was improved by the tempering thermal cycles of the following passes. But the degree and the peak temperature range of the improvement were varied according to the indivisual microstructures.
(3) The toughness was relatively low in the area close to the base metal and high in the intermediate area between the base metal and the weld metal. In the area near the fusion line, low and high toughness regions were distributed alternately.
