Influence of high-intensity pulsed ion beam irradiation on the creep property of 316 L stainless steel

High-intensity pulsed ion beam (HIPIB) treatment is a promising technology of surface modification. In this paper, the creep property of 3 16 L stainless steel irradiated by HIPIB at incident energy fluence per shot of 1.1-3.4 J/cm(2) with 1-10 shots at 700 degrees C have been studied. It is found that the creep property of the treated specimens after 10 shots fluctuates greatly with increasing energy density per shot. HIPIB irradiation at energy density of 1.1 J/cm(2) and 2.3 J/cm2 prolong the creep rupture life and reduce the steady creep rate with respect to the original specimen. In contrast, HIPIB irradiation at 3.4 J/cm(2) proves to be detrimental, causing a shorter rupture life and a faster steady creep rate. Otherwise, at a fixed irradiation intensity of 2.3 J/cm(2) per shot, the number of shots has little effect on the creep property of the treated specimens. The specimens irradiated with 1, 5 and 10 shots all have better creep property compared to the control one and the difference between them is not big. The surface morphology and phase structure in the near surface region of the specimens before and after irradiation were analyzed by using scanning electron microscope (SEM) and X-ray diffraction (XRD), respectively. It is shown that the HIPIB irradiation can smooth the surface of the specimens, which can restrain the production of the surface crack. And the presence of a preferred orientation implies the treatment creates an intense compression wave and high dislocation density in the surface layer of the irradiated specimens, which hinders the dislocations movement. (c) 2007 Elsevier B.V. All rights reserved.