遷移温度域の破壊靭性評価のための新しい統計処理法 : 平均化形状母数を用いたワイブル分布による解析

概要

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Scatter of cleavage fracture toughness K_<Jc> in the transition region can often be quite extensive. Approaches based on two- or three-parameter Weibull distribution have been used to predict the lower-bound fracture toughness from scattered data sets. However, for small data sets, an approach is often unavailable to estimate the lower-bound value with a high degree of confidence because of difficulty of determining the correct Weibull slope m. In this paper, based on a large number of experimental data, an empirical relationship among Weibull slope m, yield strength σ_ys, average value of fracture toughness K_<Jc(avg)> and specimen thickness B, has been developed as m=6.98+3.74 log[B/(K_<Jc(avg)>/σ_<ys>)^2]. When the averaged slope value was determined and the lower-bound fracture toughness K_<Jc0.03> was predicted using this relationship for A508 C1.3 and A533B steels tested in JSPS/MPC RRT, a more appropriate result was obtained than those obtained using the previous 2-parameter Weibull method and 3-parameter Weibull method in ASTM Draft with m=4 and K_<min>=20 MPa√<m>.
一般社団法人日本機械学会の論文
1996-12-25