Abstract
In this study, fretting tests of a GCr15 steel ball against a nickel titanium (NiTi) shape memory alloy plate (NiTi/GCr15) are performed on a horizontal servo-hydraulic fretting machine. It is found that the martensite reorientation plays an important role in the fretting behaviour of NiTi. Similar to that in a cyclic torsion test, the shear-induced martensite reorientation deformation of NiTi is reversible in tangential fretting, where the material undergoes a cyclic shear process. With an increase in the number of fretting cycles, the additional tangential displacement due to the martensite reorientation deformation in NiTi reaches its peak value at about 50–100 cycles after the initial increase, and finally decreases to a constant value after 1000 cycles. As a result, the martensite reorientation in fretting increases the elastic-accommodation ability of NiTi/GCr15 pairs, and further expands the partial slip regime of NiTi/GCr15 pairs. In addition, similar to the martensite phase transition in NiTi, the martensite reorientation in NiTi exhibits a strong shielding effect to decrease the contact stress of NiTi/GCr15 pairs and improve the wear resistance of NiTi.
Get full access to this article
View all access options for this article.