High temperature mechanical properties and surface fatigue behavior improving of steel alloy via laser shock peening

• The properties of 00Cr12 were improved by laser shock processing.
• A deep layer of residual compressive stresses was introduced.
• Fatigue life was enhanced about 58% at elevated temperature up to 600 °C.
• The pinning effect is the reason of prolonging fatigue life at high temperature.

Laser shock peening was carried out to reveal the effects on ASTM: 410L 00Cr12 microstructures and fatigue resistance in the temperature range 25–600 °C. The new conception of pinning effect was proposed to explain the improvements at the high temperature. Residual stress was measured by X-ray diffraction with sin2ψ method, a high temperature extensometer was utilized to measure the strain and control the strain signal. The grain and precipitated phase evolutionary process were observed by scanning electron microscopy. These results show that a deep layer of compressive residual stress is developed by laser shock peening, and ultimately the isothermal stress-controlled fatigue behavior is enhanced significantly. The formation of high density dislocation structure and the pinning effect at the high temperature, which induces a stronger surface, lower residual stress relaxation and more stable dislocation arrangement. The results have profound guiding significance for fatigue strengthening mechanism of components at the elevated temperature.