Study on microstructure regulation and strengthening-toughening mechanism of WC-8Co cemented carbide by laser shock peening

In this research, we have successfully developed a low-pulse energy laser shock peening (LSP) technology and applied it to WC-8Co cemented carbide tools, aiming to significantly enhance their mechanical performance. Through a systematic investigation, we explored the effects of laser power and the number of scanning passes on the mechanical properties and microstructure of the tools, as well as the underlying strengthening and toughening mechanisms of LSP. Our findings reveal that when the laser power was optimized at 0.4 mj and the tool was subjected to 2 scanning passes during LSP treatment, there was a remarkable improvement in the tool's flexural strength and hardness, increasing by 27.9 % and 39.8 %, respectively. This study underscores the potential of LSP as an effective method for improving the performance of cemented carbide tools. The relative density reached 98.1 %, grain size reduced to 1.06 mu m, and residual compressive stress reached -1871MPa. Additionally, under the induction of low-pulse energy, a multi-level construction of material microstructures is achieved, resulting in a unique non-uniform grain structure along the depth direction with a gradient distribution. This effectively inhibits the initiation and propagation of cracks, thus significantly enhancing the mechanical properties of the tool. These findings, applicable to cemented carbide tool materials, open up new avenues for the development of novel high-performance tools for high-speed machining.