Abhishek Telang

Surface amorphization of NiTi alloy induced by Ultrasonic Nanocrystal Surface Modification for improved mechanical properties

We report herein the effects of Ultrasonic Nano-crystal Surface Modification (UNSM), a severe surface plastic deformation process, on the microstructure, mechanical (hardness, wear), wettability and biocompatibility properties of NiTi shape memory alloy. Complete surface amorphization of NiTi was achieved by this process, which was confirmed by X-ray diffraction and high-resolution transmission electron microscopy. The wear resistance of the samples after UNSM processing was significantly improved compared with the non-processed samples due to increased surface hardness of the alloy by this process. In addition, cell culture study demonstrated that the biocompatibility of the samples after UNSM processing has not been compromised compared to the non-processed sample. The combination of high wear resistance and good biocompatibility makes UNSM an appealing process for treating alloy-based biomedical devices.

Effects of Ultrasonic Nanocrystal Surface Modification on the Residual Stress, Microstructure, and Corrosion Resistance of 304 Stainless Steel Welds

In this study, ultrasonic nanocrystal surface modification (UNSM) of 304 stainless steel welds was carried out. UNSM effectively eliminates the tensile stress generated during welding and imparts beneficial compressive residual stresses. In addition, UNSM can effectively refine the grains and increase hardness in the near-surface region. Corrosion tests in boiling MgCl2 solution demonstrate that UNSM can significantly improve the corrosion resistance due to the compressive residual stresses and changes in the near-surface microstructure.

Effects of Ultrasonic Nano-Crystal Surface Modification on the Microstructure and Properties of 304 Austenitic Stainless Steel

In this study, the effects of Ultrasonic Nano-crystal Surface Modification (UNSM) on the microstructure changes and the mechanical properties of austenitic stainless steel 304 were studied. Due to the dynamic impacts induced by the multiple strikes during UNSM, surface nanocrystallization and transformation to martensite has been achieved. The work-hardened surface layers (3.5 times the original hardness) lead to significant improvement in the mechanical properties as measured by nano-indentation and tensile test. The results demonstrate that UNSM is a powerful surface processing technique that can improve component mechanical properties and performance.Copyright