Investigation on mechanical properties and surface strengthening mechanism of the cemented carbide processed by laser shock peening
Xuming Zha, Linqing Xi, Yunwu Guo, Xiao Chen, Xiuyu Chen, Bicheng Guo, Yi Li, Zhilong Xu, Feng Jiang
Abstract
Cemented carbide has been widely used for the manufacturing due to the comprehensive properties such as high hardness, wear resistance and good toughness. Nevertheless, within the challenge of extreme working environment, it is of great significance to enhance the mechanical properties of cemented carbide components. In this study, the influence of laser shock peening on the mechanical properties and strengthening mechanisms of cemented carbide were systematically investigated. Results revealed that the grain refinement of cemented carbide was emerged after the laser shock peening treatment. The average tungsten carbide (WC) grain size of cemented carbide under the untreated and 20 laser shock cycles condition was about 1.82 and 1.62 μm, respectively. Also, the percentage of WC grain size with less than 1 μm was improved from 21.4% to 38.3%. High density dislocations and the mechanical twins within the WC grains after laser shock peening treatment could contribute to the formation of gradient nanostructure and the improvement of mechanical properties. Under 20 laser shock cycles, optimal mechanical properties of cemented carbide were achieved. The hardness, fracture toughness and residual compressive stress could reach to 18.68 GPa, 13.5 MPa ⋅m 1/2 and 1673.1 MPa, respectively. In addition, the deterioration of mechanical properties and crack propagation could be appeared due to the excessive hardening of the surface layer of cemented carbide with the number of laser shock peening exceeding 20 cycles. This study could provide effective guidance for the mechanisms of laser shock peening and the selection of appropriate laser shock parameters for cemented carbide workpiece.