シャルピーサイズ試験片によるJ_<Ic>破壊じん性試験およびその溶接部じん性評価への適用について

概要

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Since specimens taken from weldments or thermally simulated samples have a size limitation, a need has arisen to measure fracture toughness by using Charpy-size small specimens. In this study, J_<Ic> fracture toughness tests using two types of specimens (compact and three-point-bend specimens) with various dimensions were conducted for medium strength steels by the unloading compliance method in order to determine the applicability of Charpy-size specimens. Also, the metallurgical effect on fracture toughness of the heat-affected zone was discussed by the J_<Ic> test results of Charpy-size thermally simulated specimens. The following conclusions were obtained: (1) By using a side-groove to 20% of the original thickness of the specimen, J-resistance curves independent of specimen configuration were obtained. (2) Although Charpy-size specimens with side-groove did not satisfy the size requirement of J_<Ic> validity (B, W-a≥25J_<Ic>/σ_f), they had the same critical I value at the crack initiation as that of the larger-size specimens. (3) J_<Ic> fracture toughness of the heat affected zone can be expressed very well by the experimental equation J_<Ic>= (-Aσ_B+B)/S where A=0.152, B=11.7, σ_B: tensile strength in kg/mm^2 and S : area fraction of nonmetallic inclusions in percent.
社団法人日本材料学会の論文
1984-05-15