703 下限界近傍の高温疲労き裂伝ぱ挙動に関する研究(GS-4 機械材料・材料加工(1))

概要

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Fatigue crack growth behaviors at elevated temperatures were investigated for SUS304 stainless steel and Ni-base superalloy MGA1400 Fatigue crack growth tests were conducted in the near-threshold region using single-edge-cracked specimens of SUS304 stainless steel at 550 (℃), and using SEC specimens and center-cracked specimens of the MGA1400 alloy at 900 (℃). Crack growth rates of SUS304 in a vacuum were compared with those in air. It was found that the crack growth rate da/dN in a vacuum was as low as one-tenth of that in air. Threshold value, Δ K_<th>, was higher than that in air. The crack growth restarted when the maximum stress intensity factor, K_<max>, was increased for a crack exhibiting threshold behavior. For the MGA1400 alloy, the threshold value, Δ K_<th>, of the directionally solidified alloy (DS alloy) was lower than that of the conventionally cast alloy (CC alloy).
一般社団法人日本機械学会の論文
2001-03-16