Comparison between Shot Peening, Cavitation Peening, and Laser Peening by Observation of Crack Initiation and Crack Growth in Stainless Steel

Abstract

The traditional technique used to modify the surface of a metallic material is shot peening; however, cavitation peening, a more recent technique in which shot is not used, was developed, and improvements in the fatigue strength of metallic materials were demonstrated. In order to compare the fatigue properties introduced by shot peening with those introduced by cavitation peening, crack initiation and crack growth in specimens of austenitic stainless steel (Japanese Industrial Standards JIS SUS316L) treated using these techniques were investigated. With conventional cavitation peening, cavitation is produced by injecting a high speed water jet into water. In the case of submerged laser peening, bubbles are generated using a pulsed laser after laser ablation, and the impact produced when the bubbles collapse is larger than that due to laser ablation. Thus, in this study, cavitation peening using a water jet and submerged laser peening were investigated. To clarify the mechanisms whereby the fatigue strength is improved by these peening techniques, crack initiation and crack growth in specimens with and without treatment were examined by means of a K-decreasing test, where K is the stress intensity factor, and using a constant applied stress test using a load controlled plane bending fatigue tester. It was found that the improvement in crack initiation and the reduction in crack growth were roughly in a linear relationship, even though the specimens were treated using different peening methods. The results presented here show that the fatigue strength of SUS316L treated by these peening techniques is closely related to the reduction in crack growth, rather than crack initiation.

Effect of compressive residual stress introduced by cavitation peening and shot peening on the improvement of fatigue strength of stainless steel

“…This tendency is consistent with the result that the surface residual stress and the surface Vickers hardness had good correlation with the threshold stress intensity factor range DKth, which was obtained by a K-decreasing test using a load-controlled plane bending fatigue tester (Soyama, 2020a). Fig.13 Relationship between estimated yield stress, sy est, and fatigue strength, sf.…”

“…Because the bending moment was decreased during the last cycles, as the displacement-controlled plane bending fatigue tester was used at the present study. The comparison between shot peening and cavitation peening by observation of crack initiation and crack growth in stainless steel using a special made load-controlled plane bending fatigue tester was in the reference (Soyama, 2020a). If the specimen was unbroken after N = 10 7 cycles, the test was stopped.…”

Cavitation Peening: A Review

“…The geometry of the gear in Figure 21 is that of the gear tested in the reference [15]. To clarify the mechanism of improvement in fatigue strength by cavitation peening, the crack initiation and crack growth of a surface modified layer treated by cavitation peening were evaluated in comparison with other peening methods [144,145]. cavitation can generate inactivity layer by oxidation [139].…”

Optimization of Residual Stress Measurement Conditions for a 2D Method Using X-ray Diffraction and Its Application for Stainless Steel Treated by Laser Cavitation Peening

“…As residual stress is one of the most important factors related to the fatigue strength of metallic materials [ 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 ], it is worth measuring the residual stress in local areas subject to fatigue crack nucleation. It is well known that conventional welding causes tensile residual stress near the welded line due to the heat-affected zone (HAZ) [ 9 , 10 , 11 , 12 ].…”