Effect of Weld Heat Input on Weld Cracking in 80kg/mm² High-Strength Steel

Abstract

It has been reported that increasing weld heat input is effective in preventing delayed fracture because it would delay cooling after welding and consequently lengthen the time of structural improvement and discharge of diffusive hydrogen. On the other hand, a higher weld heat input tends to increase thermal stress and restraint stress, which in turn can promote delayed fracture.
In the present study, the relationships of weld heat input to delayed fracture (cracking) and restraint stress are investigated experimentally.
The result are as follows;
(1) In the formula σ_w=mK, the value of m varies with heat input.
(2) Increase of weld heat input result in a higher restraint stress, which promotes cracking.
(3) Increase of weld heat input does not lead to a lower preheating temperature.