Prevention of the Transverse Cracks in Heavy Section Butt Weldments of 2 1/4Cr-1Mo Steel through Low Temperature Postweld Heat Treatment : (Report 2) Correlation between Hydrogen Concentration and Practical Welding Conditions

概要

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It has been already found out that all the thing to be done in order to prevent the transverse cracks which occur in the thick weldments of the submerged arc welding process is to decrease hydrogen concentration in the welded zone and for this purpose a low temperature postweld heat treatment was a very effective method. As the first step for clarifying the concrete conditions of the low temperature postweld heat treatment to prevent 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.
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1979-10-01