Effect of Laser Shock Peening on Fatigue Performance of Fracturing Pump

Hydraulic fracturing is widely accepted and has become the most useful method to increase exploiting production of shale oil and gas in more complex geological environment. As the key component of the hydraulic fracturing, fracturing pump bears high cyclic pressure and is prone to fatigue failure around intersection line of the fluid cylinder, which is closely associated with the material surface state. In this paper, residual stress and axial tension fatigue test are investigated on the specimens with and without Laser Shock Peening (LSP) treatment. Numerical simulation is conducted to identify stress distribution and LSP region of fracturing pump, which is then subjected to LSP and fatigue performance test. Results showed that LSP produced a maximum compressive residual stress (CRS) of up to 730 MPa on the specimen surface and a CRS layer with a thickness of 1.5 mm under the upper surface. Tension-tension fatigue life was increased by 141.08% at 800 MPa after LSP treatment. Stress concentration of the fracturing pump was located at intersection line according to finite element analysis. And then, LSP region was designated as the area where Mises stress larger than 80% of Max. The service life was increased by 68.3% with subsequent LSP which was attributed to the compressive residual stress.