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对7075高强铝合金试样进行传统的机械喷丸强化与新的激光冲击强化工艺试验,对比它们产生的表面粗糙度、表层显微硬度与残余应力场的分布特性与演变规律,分析喷丸强化工艺对试样在低应力幅下的疲劳寿命改善作用。结果表明,表层残余压应力场分布合理性及其应力松弛趋势是提高试样疲劳寿命的主要因素,机械喷丸同时引起可观的应力集中,需要制定合理的组合式喷丸工艺,以缩小与激光冲击强化间的差距。激光冲击强化可显著改善疲劳性能的最主要因素是具有高的表面残余压应力值,以及持续保持应力影响深度的能力。而机械喷丸主要是高的残余压应力峰值及其向材料内层转移的能力。
The conventional mechanical shot peening and the new laser shock peening test were carried out on the 7075 high-strength aluminum alloy specimens. The surface roughness, surface micro-hardness and residual stress field distribution characteristics and evolution were compared. The effects of shot peening The process improves the fatigue life of the specimen under low stress amplitude. The results show that the distribution of surface residual compressive stress is reasonable and its stress relaxation trend is the main factor to improve the fatigue life of the sample. Mechanical shot peening also causes considerable stress concentration. It is necessary to formulate a reasonable combination of shot peening process to reduce the laser Impact of strengthening the gap between. The most important factor that laser shock enhancement can significantly improve fatigue performance is the high surface residual compressive stress and the ability to sustain the depth of stress impact. The mechanical shot peening is mainly the high residual compressive stress peak and its ability to transfer to the inner material.