高張力鋼溶接熱影響部の変態特性と遅れ割れ

概要

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Underbead cracking was investigated in relation to the progress of isothermal transformation in the heat-affected zone of two high tensile strength steels. C.C.T. diagram for one of the two steels was determined using specimens austenitized in hydrogen and in vacuum. Delayed cracking tests were carried out using specimens, into which hydrogen was charged in austenitic and martensitic states. Main results obtained are summarized as follows : 1. Underbead cracking is closely related with the progress of isothermal transformation in the welding heat-affected zone. 2. Holding time for the prevention of underbead cracking is shortest in the intermediate transformation range. 3. Below the Ms point, longer holding time is required to prevent underbead cracking with a lowering of temperature. 4. Hydrogen dissolved in steel does not play any significant role in the transformation. 5. From delayed cracking tests on two series of high tensile strength steel specimens containing the same amount of hydrogen charged in austenitic and martensitic states, incubation period for cracking in the former series was found to be about ten times longer than in the latter.
社団法人溶接学会の論文
1970-12-25