Laser shock processing of aluminium alloys. Application to high cycle fatigue behaviour
Laser shock processing of aluminium alloys. Application to high cycle fatigue behaviour
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DOI：
10.1016/0921-5093(95)10084-9
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发表时间：
1996-06-15
期刊：
影响因子：
6.4
通讯作者：
Lieurade, HP
中科院分区：
文献类型：
--
作者：
Peyre, P;Fabbro, R;Lieurade, HP
将目标金属样品置于极短脉冲（约20 ns）的强（GW cm（-2））激光下，通过表面等离子体产生传播到第一毫米深度的高压应力波，这通常被称为激光冲击处理（LSP）。本工作的目的是评估这种新工艺对A356，A112 Si和7075铝合金循环性能的作用。为了确定最佳冲击条件，对疲劳性能改善的主要因素进行了研究。这些主要是压缩残余应力（RS）的水平，其中大范围的入射冲击条件进行。我们发现，应力水平是非常敏感的激光能量密度和当地的影响，和实验RS测量结果与分析建模结果吻合得很好。相比之下，Nas发现传统的喷丸（SP）处理导致更高的表面硬化和RS水平，但在LSP之后没有观察到非常有害的粗糙化。对激光处理、喷丸处理和未处理的缺口样品进行的高周（10（7））疲劳试验表明，LSP作为一种新的、有前途的方法，可有效提高结构的疲劳极限σ（D），特别是与SP所显示的提高（+22% vs. + 10%）相比。根据裂纹检测的电测量，疲劳性能的改善与LSP主要发生在裂纹萌生阶段。
Subjecting target metallic samples to a very short pulse (about 20 ns) of intense (GW cm(-2)) laser light generates, through a surface plasma, a high-pressure stress wave propagating to the first millimetre in depth, which is commonly called laser shock processing (LSP). The purpose of this work was to evaluate the role of this novel process on the cyclic properties of A356, A112Si and 7075 aluminium alloys. Major contributors to the fatigue performance improvements were investigated in order to determine the optimum shock conditions. These were mainly compressive residual stress (RS) levels for which a large range of incident shock conditions was performed. We showed that stress levels were very sensitive to the laser fluence and the number of local impacts, and experimental RS measurements were found to be in good agreement with analytical modelling results. In comparison, a conventional shot peening (SP) treatment Nas found to lead to higher surface hardening and RS levels, but with a very detrimental roughening not observed after LSP. High cycle (10(7)) fatigue tests carried out on laser- processed, shot-peened and untreated notched samples illustrated the efficiency of LSP as a new, promising method to improve the fatigue limits sigma(D) of structures, especially in comparison with enhancements displayed by SP (+22% vs. + 10%). According to crack detection electric measurements, fatigue performance improvements with LSP mainly occurred during the crack initiation stage.