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Surface properties enhancement of Inconel 718 alloy by ultrasonic roller burnishing coupled with heat treatment

Shen Xuehui, Gong Xianhong, Wang Baolin, He Jianqun, Xu Chonghai, Su Guosheng

Archives of Civil and Mechanical Engineering

2021

Vol. 21, no. 3

618--634

Ultrasonic burnishing (UB), in which a ball tip is usually utilized, has been proved to be an effective method for metal surface strengthening. In this study, a roller tip was employed in the ultrasonic burnishing of Inconel 718 alloy (ultrasonic roller burnishing, URB). Meanwhile, a new surface modification technique, i.e., a combination of URB and heat treatment (URB/HT), was advanced to achieve better surface finishing. The surface integrities together with the mechanical behaviors of various samples treated by URB or URB/HT were experimentally examined and compared. Meanwhile, the transient stress distribution of the being treated materials with two treatments was comparatively analyzed by the FEA method. As result, compared with URB, the URB/HT-treated sample had better surface morphology, lower surface roughness, higher micro-hardness, and more well-distributed compressive residual stress. Furthermore, URB/HT-treated samples presented higher yield strength and lower wear rate in comparison with the URB-treated ones. The reduction of deformation resistance and easy flow of the near-surface material during URB/HT treatment mostly contributed to the excellent surface finishing.

New approach towards the machining process after laser cladding

Shen Xuehui, Su Hao, Wang Jiatian, Zhang Changsheng, Xu Chonghai, Bai Xiaolan

Archives of Civil and Mechanical Engineering

2021

Vol. 21, no. 1

136--152

As a chip-free and high-efficiency three-dimensional forming technology, laser cladding has been successfully applied in the green manufacturing and remanufacturing of some high-end engineering parts/components. However, in most cases, cladding coatings need to be machined due to the poor surface finishing by sole laser cladding technique. The study aims to explore an effective way to replace the current machining process after laser cladding, which is supposed to be incapable of satisfying the various technical requirements of some high-demand engineering parts/components. With this purpose, three new surface strengthening processes, i.e. ultrasonic roller burnishing at ambient temperature (URB), ultrasonic roller burnishing at warm temperature (UWB), and UWB coupled with continuous heat treatment (UWB/HT), were proposed and comparatively explored. The contact stresses between the contact pairs in URB were calculated and analyzed in theory. A set of ultrasonic roller burnishing equipment was self-manufactured to perform the experiment. Comparing with the conventional process, the three new processes were evaluated mainly from aspects of surface finishing, the adhesion behavior and corrosion resistance of the finished surface. Summarily, ultrasonic warm burnishing coupled with continuous heat treatment (UWB/HT) is considered to have the greatest potential to achieve the effective machining after laser cladding with excellent surface finishing over the other two strategies, which is expected to further advance the application of laser cladding technique particularly in the fabrication of some high-demand products serving in harsh conditions.

Surface integrity enhancement of austenitic stainless steel treated by ultrasonic burnishing with two burnishing tips

Shi Ya-Long, Shen Xue-Hui, Xu Guo-Feng, Xu Chong-Hai, Wang Bao-Lin, Su Guo-Sheng

Archives of Civil and Mechanical Engineering

2020

Vol. 20, no. 3

224--240

A set of ultrasonic burnishing equipment with two different burnishing tips was designed and manufactured, with which a series of experiments were performed to explore the effects of process parameters and burnishing tips on the surface integrity of austenitic stainless steel material being treated by ultrasonic burnishing (UB). Based on the experiment data, the two surface treatments, i.e. UB with ball tip and UB with roller tip, were comparatively assessed together with the other two surface machining methods of fine turning and grinding. As a further study, a microscopic FE model was built to investigate the three-dimensional transient stress and strain field inside the being treated material. It was found that parameter combination is determinative to surface finishing in UB process, and static pressure and burnishing pass are supposed to be the two most significant parameters for surface integrity of the treated sample. On the whole, roller tip is more preferable to achieve good surface enhancement than ball tip. The superposition of ultrasonic vibration leads to the dynamic change of the stress and strain field in UB, resulting in the oscillating propagation of stress wave inside the material, which gives explanation for the good performance of UB than that of conventional burnishing without ultrasonic.