13Cr マルテンサイト系ステンレス鋼の 3% 食塩水中における腐食疲労挙動と粒界腐食性との関連

概要

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Corrosion fatigue tests of 13Cr martensitic stainless steels in several tempered states were carried out in 3%NaCl solution at room temperature, and the effect of metallurgical variables on corrosion fatigue strength at 10^7∿10^9 cycles was investigated. The followings are found : 1) Corrosion fatigue strength σ_<WC> monotonically decreases with the loading cycle. At 10^9 cycles, σ_<WC> decreases to 50MPa for some tempered states. 2) In a high cycle region, σ_<WC> strongly depends on the tempering conditions, and σ_<WC> of the steels sensitive to intergranular corrosion was relatively low because of the formation of deep pits. 3) The apparent stress intensity factor for corrosion fatigue cracking, K_<cf>, is about 1.6∿2.5MPa√<m> at 10^7∿10^9 cycles and independent of tempering conditions. 4) The rate determining process for corrosion fatigue life under high cycle and low stress conditions appears to be that of pitting corrosion. 5) One of the effective methods to increase corrosion fatigue strength may be careful selection of the tempering conditions in which the Cr depleted zone is not formed.
社団法人日本鉄鋼協会の論文
1989-03-01