Y_2O_3分散合金の高温疲労き裂進展抑止機能

概要

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The arrest function in fatigue crack propagation at 25 and 550℃ in air was investigated for Fe-20Cr alloys containing dispersed oxide particles of Al_2O_3, ZrO_2 and Y_2O_3 in weight percents from 0.3 to 1.2. The P_<max>-constant ΔK-decreasing test, where the minimum load, P_<min>, increased with increasing crack length while the maximum load, P_<max>, remained constant, was employed in order to avoid crack closure. The main conclusions obtained are as follows : (1) Fatigue crack propagation properties including the threshold were independent of the material at room temperature under the closure-free condition. The fatigue threshold values at 550℃ were higher than those at room temperature for all materials. In addition, the threshold values at 500℃ were about 50% higher for Y_2O_3-dispersed alloys than those for the base alloy and Al_2O_3-or ZrO_2-dispersed alloys. (2) The increase of threshold level at 550℃ for Y_2O_3-dispersed alloys was explained in terms of suppression of the spalling of the oxide layer formed at the fatigue crack tip by dispersed Y_2O_3 particles. Accordingly, we concluded that Y_2O_3 dispersion could show the arrest function of the fatigue crack propagation at elevated temperatures.
一般社団法人日本機械学会の論文
1994-07-25