Experimental investigation of femtosecond laser shock peening on surface characterizations of NiTi alloy

Hao Wang, Ruhr-Universität Bochum, Bochum, Germany
Evgeny Gurevich, Ruhr-Universität Bochum, Bochum, Germany
Andreas Ostendorf, Ruhr-Universität Bochum, Bochum, Germany

Femtosecond laser shock peening (FLSP) technology was used to process the surface of NiTi alloy without protective coating in air and distilled water. The surface characteristics of NiTi alloy, such as roughness, surface oxidation, micro-hardness, microstructure and wear resistance, were studied after FLSP treatment. The surface roughnesses were changed and FLSP treatment in distilled water can generate smoother surface than that treated in air. FLSP treatment can induce grain refinement in the surface layer of NiTi alloy, which can result in an increase in microhardness. The result of scratch testing reveals that the FLSP treatment can improve the friction and wear resistance on the surface of NiTi alloy. This enhancement of wear resistance may be attributed to increase of microhardness and the grain refinement generated by significant plastic strain accumulation on the surface of NiTi alloy after FLSP treatment.

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