18%Niマルエージング鋼の疲労特性に及ぼす逆変態オーステナイトの影響

概要

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The influence of reversion austenite on the fatigue behavior of a maraging steel has been investigated by using 18%Ni-8%Co-5%Mo steel. The behaviors of age hardening and reversion from martensite to austenite were examined first under various aging conditions in the temperature range of 750〜850K. These aging conditions were chosen so that a selected volume fraction of austenite(γ vol%=1, 2, 3 or 24%)was formed in the age hardened maraging steel. The specimens were subjected to fatigue test, crack growth test and fractography. The results obtained are as follows: (1)The formation of reversion austenite results in a great improvement of fatigue strength. Especially, a small amount of austenite(2〜3 vol%)markedly increases the fatigue limit of a maraging steel without reducing the hardness so much. Due to the existence of reversion austenite, crack growth tends to be suppressed and the maximum length of non-propagating crack becomes longer. (2)The existence of reversion austenite improves the fatigue fracture toughness.
社団法人日本材料学会の論文
1995-02-15