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1

To decrease the turning-induced pitting susceptibility of laser-cladded Fe–Cr–Ni layer by low plasticity burnishing

Zhang Peirong, Hu Shunrui, Lv Tao, Du Jin, Su Guosheng, Liu Zhanqiang, Xu Chonghai

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 4

art. no. e179, 2022

EN

Corrosion resistance of machined surface and its correlation with surface roughness have been the important concerns for sustainability of the final products. However, the pitting corrosion of laser-cladded Fe–Cr–Ni layers by turning exhibits susceptibility to surface roughness characteristics. In present study, the generation mechanism of pitting susceptibility by turning and the effect of burnishing on decreasing the pitting susceptibility were explored. To this end, a theoretical model of the potential difference between roughness peaks and valleys was established with considering the functional parameters of the surface roughness. Then, the correlations between the potential difference and pitting characteristics including pitting depth, width and area were analyzed in order to reveal the generation mechanism of pitting susceptibility. The occurrence of pitting corrosion could be predicted by the local potential difference, which was higher at the location where pitting corrosion would occur while lower where pitting corrosion did not occur. Finally, the influence of each functional parameter of surface roughness on the potential difference was analyzed using the proposed model, with which the machining schematics were discussed. On the basis of this research, it was expected to improve the corrosion resistance of the claddings by turning and subsequent burnishing process chain.

2

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.

3

Sustainable manufacturing: re-contouring of laser cladding restored parts by machining method with cutting energy management

Zhang Peirong, Du Jin, Zhou Tingting, Su Guosheng, Huang Weimin, Liu Zhanqiang

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 2

167--176

EN

Laser cladding has been commonly utilized for restoring high value-added parts. However, the poor surface quality becomes key technological barrier which restricts its widespread applications. In the paper, re-contouring strategies by machining method are explored for minimal energy consumption as well as required surface roughness. Firstly, the effect of structural characteristics of the laser-cladded workpiece on specific cutting energy was explored by means of layer-by-layer turning and orthogonal cutting. Results indicated that the specific cutting energy increased, and the machining chatter/vibration exacerbated with decreasing coating thickness under fixed cutting parameters. The reason can be summarized as a result of the effect of elastoplastic deformation behavior across the interface. Then, the influences of depth of cut and feed on specific cutting energy in finish turning were addressed. Results indicated that the specific cutting energy reduced with increasing depth of cut and feed in the form of power functions. In addition, energy efficiency decreased with an increase in uncut chip thickness and cutting speed. On basis of this work, large feed and low cutting speed with the adoption of wiper inserts were recommended for minimizing energy consumption within surface roughness requirement.

4

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.