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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

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2021

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Vol. 21, no. 3

618--634

EN

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.

2

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

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2021

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Vol. 21, no. 1

136--152

EN

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.

3

Effect of turning-induced initial roughness level on surface roughness and residual stress improvements in subsequent burnishing

Zhang Peirong, Du Jin, Zhang Hui, Su Guosheng, Shen Xuehui, Huang Weimin, Liu Zhanqiang

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 3

241--253

EN

The hydraulic support column of comprehensive mining equipment is the most important part, subjecting to corrosion, wear and collision. The scrapped columns are restored by laser cladding to replace plating process for enhancing service life. All that is required after laser cladding is subtractive machining to improve the surface quality of the laser cladded coatings. This work focused on the remanufacturing machining strategy for re-contouring the laser cladding restored columns. First, surface roughness model of the laser cladded coatings by turn-burnishing was presented based on the surface generation mechanism. Then the effect of turning-induced roughness level on the surface roughness improvements by subsequent burnishing is addressed. Results indicated that the reduction of surface roughness by burnishing showed positive correlation with the feed in initial turning with conventional inserts, while was negatively correlated with the feed in initial turning with wiper inserts. In addition, the initial turning-induced surface roughness level generated great influence on the residual stress improvement in subsequent burnishing. Based on the findings, proper remanufacturing machining strategies for re-contouring the laser cladding-restored hydraulic support columns were presented.