3.5% Ni 鋼の再現溶接熱影響部の破壊靱性について : 低温用鋼の破壊靱性について(第 2 報)

概要

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3.5% Ni steel for low temperature service was subjected to some synthetic welding cycles. These J integral fracture toughness, J_<Ic> and critical crack-tip opening displacement, δ_c were obtained through three point bend test conducted at low temperature range from -196℃ to -80℃. The main results obtained were as follows; 1) Judging from the results of manual wold sample with covered electrode (3.5% Ni and 6.5% Ni) through V-notch Charpy impact test, the absorbed energy was better in the following order. base metal>weld HAZ>weld metal But the energies of synthetic HAZs were much inferior to those of weld HAZ mainly due to grain coarsening. 2) J_<Ic> values and δ_c values in synthetic HAZ were inferior to those of as-received steel in evrey test temperature. But the remarkable recovery of J_<Ic> and δ_c was obtained in synthetic HAZ by a reheat of the temperature at 700℃ to 800℃ and a rapid cooling, which was due to the formation of a tempered martensite and a bainite structure. Fracture toughness of the reheated synthetic HAZ was about two to three times larger compared to that of as-received specimen. 3) Maximum J_<Ic> and δ_c were observed at 18 to 40 sec, chanigng the cooling time from 800℃ to 500℃ in synthetic HAZ, which was heated at peak temperature of 1300℃.
社団法人溶接学会の論文
1982-05-05