1980 Volume 49 Issue 2 Pages 129-136
It has been already found out experimentally that all what to be done in order to prevent the occurrence of the transverse cracks which occur in the thick weldments by the submerged arc welding process is to decrease hydrogen concentration in the welded zone and that, to do so, a low temperature postweld heat treatment was a very effective method.
Then, as the first step for clarifying the concrete conditions of the low temperature postweld heat treatment to prevent the occurrence of the cracks, in this paper the correlation between the hydrogen concentration in the welded region just after welding and the practical welding conditions, such as preheat and interpass temperatures, welding speed, plate thickness, and dimensions of a welded structure, is investigated by using an analytical computer program employing the finite element method which can estimate the hydrogen distributions presented in the previous paper.
First, we introduce a parameter τ of the hydrogen diffusion during welding, of which values can be determined both by the welding thermal history and by the temperature dependence of the hydrogen diffusivity coefficients, and clarify the correlation between its parameter and the hydrogen concentration just after welding. Next, considering the compensatory heating by gas burners during welding, we find out the relationship between its parameter and the welding conditions.
