SM50 鋼溶接熱影響部の金属組織学的検討と最高到達温度の推定

概要

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Metallographic changes in the weld heat-affected zone (HAZ) for the ferritic and pearlitic steel such as Steel SM50 were investigated, and a maximum temperature at any portion of the HAZ was estimated from the relation between microstructual changes and the theoretical formula for one dimentional thermal conduction. Results are as follows; (1) The observation of the fusion line was facilitated through the application of an interference microscope to the weld zone etched with the saturated picric acid solution containing an anion activator. (2) The massive ferrite at the portion heated to 950℃ in the synthetic HAZ with a cooling time from A_3 to 500℃ of about 0.8∿4 sec, was not the ferrite retained in the base metal, but the ferrite grown from the austenite due to heating. (3) The boundary between the HAZ and the unaffected zone of the base metal was clarified by the observation of macro- and microstructures. (4) The maximum temperature at any portion of the HAZ was estimated by using an equation introduced from the formula for one dimentional thermal condition due to the instantaneous plane heat source and the metallographic techniques as mentioned above in (1) and (3).
1981-10-01