SM50C 溶接ボンド部の破壊靱性とストレッチド・ゾーンについて

概要

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The concept that the toughness of low and medium strength steels is well defined by the two parameters δ_i (COD at fibrous crack initiation) and T_i (fibrous-cleavage transition temperature in fracture initiation) has been applied to the toughness evaluation of welded joint. Tests were made on the coarsegrained region of the heat-affected zone (HAZ) of SM50C by using 3 point bend specimens in the temperature range from -196℃ to room temperature. Although δ_i of HAZ specimen takes almost the same value as that of base metal, T_i's of HAZ specimens show high temperatures than those of the base metal by 60°∿70℃, for both fatigue-precracked and 0.1R mechanical-notched specimens. The value of the stretched zone depth (SZD) measured on the fracture surface shows the value of COD at fracture initiation regardless of the material (base metal or HAZ) and fracture mode (fibrous or cleavage). Therefore, the toughness of a welded joint could be evaluated by SZD instead of COD.
社団法人溶接学会の論文
1978-03-05