小型パンチ試験におけるタービンローター鋼の延性-脆性遷移挙動に及ぼす変形速度効果

概要

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The effect of deformation rate on the ductile-brittle transition behavior of temper embrittled turbine rotor steels has been investigated employing a newly developed dynamic small punch (SP) tester. It is shown that the dynamic SP test produces a clear ductile-brittle transition behavior similar to the Charpy V-notch (CVN) impact test. The ductile-brittle transition temperatures determined by fracture energy measurements and by fracture surface observations are higher about 48-90℃ than those obtained from the static SP tests. The effect of deformation rate on the relationship between FATT_<SP> and FATT_<CVN> obtained from SP and CVN tests is examined : it is found that as the deformation rate increases to 10^3 and 2.5×10^6 times, the value of α, which is a proportionality coefficient in the relationship given by FATT_<SP>=α×FATT_<CVN>, is increased to 0.45 and 0.54, respectively. From these experimental results, it is implicated that the use of the dynamic SP testing method enhances the predictability of FATT_<CVN>.
社団法人日本鉄鋼協会の論文
1992-03-01