喷丸强化对AISI 420不锈钢固体粒子冲蚀行为的影响

Effect of Shot Peening on Solid Particle Erosion Behavior of AISI420 Stainless Steel

研究了喷丸强化(SP)对AISI 420马氏体不锈钢抗固体粒子冲蚀(SPE)行为的影响,探讨了喷丸引起的表面残余压应力,表面粗糙度增大和表面加工硬化等三因素对SPE抗力的作用机制。结果表明:SP处理对AISI 420不锈钢在30°攻角下的SPE抗力无明显影响,但却降低了该钢在90°攻角下的SPE抗力。SP处理后进行表面抛光,则使该钢在两种攻角下的SPE抗力均得以提高。SP三因素对SPE抗力的作用机制主要有:表面粗糙化增大了试样表面对冲蚀粒子的有效暴露面积,因而降低了不锈钢在两种攻角下的SPE抗力;表面残余压应力能够有效抑制疲劳裂纹萌生和早期扩展,因而能有效提高AISI 420不锈钢的SPE抗力,特别是对90°垂直冲击条件下SPE抗力的提高作用更为明显;表面加工硬化提高了材料表面的微犁削抗力,因而对提高AISI 420钢在30°攻角下的SPE抗力有贡献,但是表面加工硬化层的抗多冲疲劳性能差,却不利于AISI 420钢在90°攻角下抗SPE性能的改善。

The aim of this paper is to study the effect of shot peening （SP） on solid particle erosion （SPE） behavior of AISI 420 stainless steel. The mechanisms of three factors of SP, i.e. , compressive residual stress （CRS）, surface roughness （SR） and work-hardening on SPE resistance were investigated. The results show that the SPE resistance of the shot peened specimen is decreased at 90° impingement angle, while it is hardly affected at 30° impingement angle. However, with polishing treatment to the shot peened specimen, the SPE resistance can be improved obviously at both impingement angles. These results can be explained by follow： The high SR increases the effective area under the bunch of solid particles, so it decreases the SPE resistance of the shot peened specimen. The CRS induced by SP can increase crack closure and retard crack propagation, so it improves effectively the SPE resistance, especially at 90° impingement angle. The work-hardening improves obviously the SPE resistance of the shot peened specimen at 30° impingement angle because the micro-cutting resistance of the surface is increased. However, the work-hardening decreases the resistance of SPE at 90° impingement angle due to the poor multi-impact fatigue property of the hardened surface.