Ti-6Al-4V合金の超音波疲労特性

概要

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In order to investigate the fatigue strength of Ti-6Al-4V alloy at a large number of cycles,ultrasonic fatigue tests were performed.Three heat treatment,i.e. mill anneal (MA),duplex anneal (DA),and solution treatment and aging (STA),were applied to the specimens.Although the fatigue strength obtained from this method was approximately 15 percent higher than that obtained from the conventional fatigue test,the general trend of these two S-N diagrams was the same.Usefulness of the ultrasonic fatigue teat as an acceleration method to determine the S-N diagram was confirmed on this alloy and the fatigue strength of the above mentioned heat treated specimens at a large number of cycles up to 2×10^9 cycles was determined.The noteworthy result was that there seemed to exist a fatigue limit in this alloy from the data up to 10^8 cycles,but the fatigue strength became decreased at further number of cycles.This result was obtainable only by performing the fatigue test in a longer period like up to 10^9 cycles.Similarly to the tensile strength,the STA specimen showed the highest fatigue strength and the MA and the DA specimens followed.Judging from their FCP properties and fractograhies,the difference in fatigue strength among these specimens with various microstructures was caused in the atages of crack nucleation and/or microcrack growth.
社団法人日本材料学会の論文
1993-10-15