溶着金属のミクロワレに関する研究 : イルミナイト系溶接棒によるシングルビードのミクロワレの観察

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The authors studied on the phenomenon of microcracking in single bead obtained from ilmenite electrode. Electrolytic-polishing was used to detect the microcracks on the longitudinal section of a bead-on-plate specimen. Effect of cooling condition after welding, plate thickness and initial plate temperature were mainly studied. Results obtained were as follows. (1) The formation of microcracks in mild steel weld metal, previously noticed by Flanigan, has been observed in single bead from ilmenite electrode under condition of rapid cooling. The length of microcracks varied widely being often 0.3mm. and above, but most commonly about 0.1mm. (2) There was a clear trend towards increasing crack numbers with the increase of plate thickness. The specimen of 25mm. and 32mm. thick, for instance, contained microcracks when air-cooled after welding at 0℃., but no cracking was found with 19mm. thick specimen. (3) A change in initial plate tempere from 0℃. up to 40℃ had a pronounced effect, decreasing the extent of microcracking; i.e., the preheating at 40℃. was remarkable in preventing microracking even with 32mm. thick specimen. (4) The specimen of 19mm. thick, welded with ilmenite electrode and water quenched within 1min. after welding, contained microcracks, but no cracking was found even though 32mm. thick specimen with low hydrogen electrode.
社団法人溶接学会の論文
1964-10-25