油中における時効硬化Al合金の疲労強度とき裂伝ぱ形態の関係

抄録

Rotating bending fatigue tests were carried out on specimens with a small blind hole of three age-hardened Al alloys, i. e. 2017-T4, 7075-T6, and 6061-T6, in air and in oil. The main results obtained are as follows: (1) Fatigue strength of 6061-T6 decreases and those of 2017-T4 and 7075 -T6 increase, in oil as compared with those in air. (2) In 2017-T4 and 7075-T6, the mode of crack propagation is affected by the stress level and the environment. (3) The effect of oil on the crack growth rate depends on the mode of crack propagation. That is, the effect is strong in the tensile mode and weak in the shear mode.