Wear failures of components often occur and cause great economic losses in modern industry production. To obtain excellent wear resistance surface will help reduce the abrasion. Herein, a wear-resistant iron-based alloy coating was deposited on a low-carbon steel substrate by argon arc overlaying, and sequentially surface nanocrystallized through ultrasonic impact treatment (UIT). Micro-structural, mechanical property (including nanohardness and elastic modulus) and wear behavior changes of the coating before and after UIT were experimentally investigated. In addition, the wear mechanism variation owing to the application of UIT was discussed. The results show that a highly deformed nanocrystalline layer with an average grain size in the range of ~100 nm was generated at a depth of approximately 34 μm from the treated coating surface, which contains a certain amount of the deformation-induced α’-martensite phase. Compared with the as-deposited coating, the coating after UIT processing exhibits considerable improvements in the ratio of nanohardness (H) to elastic modulus (E) and better wear resistance under the same wear test conditions. The wear mechanism has also changed from the adhesive type of the as-deposited coating to an abrasive type on the introduction of a nanocrystalline microstructure.

This study aims to explore the effects of ultrasonic impact parameters on the surface modification of a stainless steel coating deposited on a medium-carbon low-alloy steel using argon arc surfacing welding. Ultrasonic impact treatment (UIT), at three different vibration strike numbers (40,000 times/(mm²), 57,600 times/(mm²), and 75,000 times/(mm²)) marked UIT–1, UIT–2, and UIT–3, respectively, was carried out to modify the surface structure and properties of the stainless steel coating. The surface morphological and structural features, phase compositions, grain size, topography, micro-mechanical properties, as well as the wear resistance of the coating before and after UIT with different impact parameters were experimentally investigated. The results of optical microscopy (OM), scanning electron microscopy (SEM), electron backscatter diffraction (EBSD), and X-ray diffraction (XRD) analyses revealed that the grain refinement accompanied by the formation of the strain-induced α′–martensite occurred on the UIT-treated coating surface. With the increase in the vibration strike number, the surface grain size and roughness decreased, while the α′–martensite content increased. Micro-hardness after UIT was increased by about 19% (UIT–1), 39% (UIT–2), and 57% (UIT–3), and the corresponding wear rate obtained was decreased by 39%, 72%, and 85%, respectively. Significant improvements in wear resistance were achieved using UIT. However, an excessive vibration strike number on the per unit area (/mm²) might result in unwanted micro-cracks and delamination on the treated surface, deteriorating the performance of the coating. These findings validate that UIT parameters (such as the vibration strike number on per unit area) are of great importance to bringing about improvements in wear performance, and UIT is found to have a high potential in modifying the surface characteristics and optimizing the mechanical performances of the deposited coating for a wide range of potential applications.