熔接衛生に関する研究 (その2) : 熱応力が熔接時の発塵に及ぼす影響

概要

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Coating materials of electrodes are rapidly heated during arc-welding. In order to study how thermal stress generated by the are-welding effects the production of dusts, samples of coating materials were rapidly thrown into an electric furnace kept at constant temperatures (every 100℃, from 100℃ to 1000℃) and were heated for 20 minutes. Obtained results were shown by the time-differential value of weight change curves. Whether the heating temperature was high or low, the thermal stress was generated ad maximum 30∼40 seconds after the beginning of heating the samples and caused to produce a lot of dusts. Heatings at 300℃∼400℃ and 500℃∼800℃ generated extreme thermal stresses. These temperatures were in accordance generally with those (below 300℃ and 450℃∼670℃) already reported. When the coating materials was rapidly heated, the thermal stress generated even below 1,000℃ could be a thermal shock, producing dusts. The thermal shock at 300℃∼400℃ caused mainly by the vaporization of hygroscopic water, which acts between structures and between crystals, developing coarse dusts. The dusts produced at 500℃∼800℃ are caused by decreasing glutinosity of the coating materials and by various changes of the crystal system. This thermal shock acts between crystals and between the internal parts of the crystal, producing fine dusts.
社団法人日本産業衛生学会の論文
1967-09-20