Cracking Parameter of High Strength Steels related to Heat Affected Zone Cracking (Report 2)

概要

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It has been impossible to predict proper welding procedures using the results of small restraint cracking tests, since the relationship between small specimens and actual welded structures has not been clear on account of their cooling rate and the intensity of restraint. In the present investigation are reproduced various intensities of restraint on small specimens, so that the effect of the restraint may be clarified.<BR>Introducing the weldment cracking parameter, Pw, a method is established to predict the adequate welding procedures for a given chemical composition of steel used, the amount of diffusible hydrogen in weld metal and the intensity of restraint of the weldments.<BR>Although the cooling processes are different depending on the size of structures, preheating method and the ambient temperature, even for the same preheating temperature, generalized welding procedures can be given by using the criterion of critical cooling time interval from 300°C to 100°C.<BR>The relationship between Pw and critical cooling time interval from 300°C to 100°C indicates the proper welding procedure which assures sound weldments without any cracks. For a given value of Pw, it is only necessary to preheat the structure in such a way that the cooling time lies above the limiting line.
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