1965 Volume 34 Issue 2 Pages 154-159
The precipitation characteristics of boron constituent in the weld heat affected zone had been already reported in the Report No. 1. As a continuation of the Report No. 1, the effect of born constituent upon the propertis of weld heat affected zone has been investigated and the following results were obtained.
1. The precipitation of boron constituent has the tendency to decrease the hardenability of heat affected zone.
2. The predominant precipitation of boron constituent decreases the ductility of heat affected zone including elongation, reduction in area in tention, test and also crack initiation angle as well as fracture angle in bend test. The precipitation also impairs impact value. With regard to the influence of the precipitate upon the ressistance for fatigue, the precipitate has no effect on the fatigue limit but it decreases the number of repeated cycles required for fracture under the stress more than fatigue limit.
From these results, it is advisable to avoid the precipitation of boron constituent in the weld heat affected zone by selecting the suitable steel composition and correct welding condition.
Much efforts has been made in our Steel Works for this purpose and the object has been almost achieved by selecting the most suitable steel composition.