鋼材の動的破壊靱性特性における温度および歪速度の影響の検討

概要

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The effect of strain rate and temperature on the dynamic fracture toughness K_<ld> and the critical COD δ_<cd> of structural steel has been experimentally studied. Dynamic tensile test was carried out using1T, 2 T and 3 T-CT type specimens produced from steel for pressure vessel of 125 mm in thickness (A 533-C1. 1). Tensile rates were changed from static (0.2 mm/s)to 8 m/s at loading device in fracture test. Test temperature were selected mainly in which the specimen fractured without unstable fibrous crack at notch tip. The results are summarized as follows. The values K_<ld >and δ_<cd >decrease with increase in tensile rate (K_i or δ). But it is supposed evidently that there is maximum tensile rate affecting to the fracture toughness behavior. Fracture toughness values obtained by present study have had not so good correlation with the strain rate and temperature parameter T_K In(A/ε) excepting the low fracture toughness level. We attempted a modification to strain rate-temperature parameter concerning to the strain rate with which it was appreciated the unification of the effect of strain rate in different strain rate excepting over 2×l0^3 strain. It is suggested to investigate the local strain behavior at the crack tip corresponding to the load point tensile rate.
社団法人日本船舶海洋工学会の論文