Fundamental Study on Cavitation Erosion Using a NiTi Shape Memory Alloy.

Abstract

In order to clarify the role of slip deformation on cavitation erosion, vibratory cavitation tests were carried out for a NiTi shape memory alloy in martensitic phase and austenitic phase. This alloy deforms plastically by the combination of slip and twinning deformation, and the erosion resistance of NiTi shape memory alloy is 500 to 1000 times higher than that of SUS316 stainless steel. The erosion resistance of austenitic phase is superior to martensitic phase, because the accumulation of slip in the austenitic phase is slower due to the superelasticity than that in the martensitic phase. The martensitic phase test with intermittent shape recovery shows a better resistance without the shape recovery, since the deformation twins produced by cavitation erosion test are eliminated by shape recovery, resulting in the delay of slip accumulation. However, the amount of shape recovery was decreased with test duration. The decreasing rate of shape recovery has a good linear relationship with the volume loss rate. It was concluded that the accumulation of slip deformation corresponds well with the volume loss rate.