The Effect Of High Energy Shot Peening On Stress Corrosion Cracking Of304Austenitic Stainless Steel

304stainless steels have good plasticity, toughness and weld ability, is widely used in various industrial fields of the national economy. However, this material is apt to cause localized corrosion phenomena such as intergranular corrosion and stress corrosion in chlorine ion solution, which bring a lot of restrictions when304stainless steels are used, and even lead to serious safety accidents. In recent years, both domestic and foreign researchs about the surface shot peening treatment to improve the mechanical properties, fatigue performance and resistance to uniform corrosion performance of materials have achieved many useful results, but the effect of high energy shot peening process parameters on performance of stress corrosion cracking of304stainless steels, yet lack of systematic research.304stainless steels and its welded joints were treated by high energy shot peening treatment with the different shot peening pressure and time in this article. The effect of high energy shot peening process parameters on surface performance of304stainless steels was studied by the analysis of XRD, scanning electron microscopy (SEM), transmission electron microscope (TEM) and micro-hardness. Through the stress corrosion test, the influence and mechanism of high energy shot peening parameters on304stainless steel stress corrosion sensitivity was studied. Main research results are summarized as follows:(1) After high energy shot peening, the parent metal and weld specimens of304stainless steels produced strong plastic deformation, induced martensite transformation. As the shot peening pressure or time increased, martensite phase gradually increased, and austenitic phase reduced correspondingly.(2) Along with the shot peening pressure or time increased, sample surface grain tapered off, and lattice distortion increase accordingly. After high energy shot peening, the surface grain of parent metal and weld specimen reached the nanoscale (15-60nm).(3) When shot peening pressure or time increased, the surface microhardness of parent metal and weld specimen increased, with the increase of distance from the specimen surface, microhardness fell rapidly and tend to be stable. (4) Through the high energy shot peening, the stress corrosion susceptibility of parent metal and weld specimen of304stainless steels decreased obviously in3.5%NaCl solution. With the shot peening pressure or time increased, the stress corrosion sensitivity of parent metal and weld specimen decreased first, then increased.(5) The effect of high energy shot peening on stress corrosion sensitivity of304stainless steel stress is divided into two aspects:grain refinement and martensite phase transformation. When the shot peening parameters were less than the critical value, the grain refinement accounted for the dominant position, along with the shot peening pressure or time increased, stress corrosion sensitivity down; Conversely, when the shot peening parameters were greater than the critical value, martensite transformation was important than grain refinement, stress corrosion sensitivity with the peening pressure increase or peening time increases, stress corrosion sensitivity rose.