Effect of laser shock processing on fatigue crack growth and fracture toughness of 6061-T6 aluminum alloy
Effect of laser shock processing on fatigue crack growth and fracture toughness of 6061-T6 aluminum alloy
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DOI：
10.1016/j.msea.2004.07.025
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发表时间：
2004-11-25
期刊：
影响因子：
6.4
通讯作者：
Morales, M
中科院分区：
文献类型：
--
作者：
Rubio-González, C;Ocaña, JL;Morales, M
激光冲击处理(LSP)是一种新的金属强化技术。这一过程产生了压缩残余应力场，提高了疲劳裂纹萌生寿命，降低了疲劳裂纹扩展速率。本研究采用6061-T6铝合金试件。采用会聚透镜，在10赫兹频率下，通过调Q的Nd：YAG激光器输出1.2J，8 ns的激光脉冲。脉冲被聚焦到直径为1.5 mm的水浸型铝样品上。分析了脉冲密度对残余应力场的影响。用打孔法计算了残余应力随深度的分布。结果表明，脉冲密度越大，残余压应力区域越大。使用密度为900、1350和2500脉冲/厘米(2)的红外(1064 Nm)辐射。对预裂纹密实拉伸试件进行了LSP工艺试验，并在R=0.1的循环载荷下进行了试验。测定了疲劳裂纹扩展速率，评价了LSP工艺参数对疲劳裂纹扩展速率的影响。比较了采用LSP工艺和不采用LSP工艺的疲劳裂纹扩展速率。此外，还测定了LSP处理和未处理的试件的断裂韧性。结果表明，LSP降低了6061-T6铝合金的疲劳裂纹扩展，提高了断裂韧性。(C)2004爱思唯尔B.V.保留所有权利。
Laser shock processing (LSP) or laser shock peening is a new technique for strengthening metals. This process induces a compressive residual stress field which increases fatigue crack initiation life and reduces fatigue crack growth rate. Specimens of 6061-T6 aluminum alloy are used in this investigation. A convergent lens is used to deliver 1.2J, 8 ns laser pulses by a Q-switch Nd:YAG laser, operating at 10 Hz. The pulses are focused to a diameter of 1.5 mm onto a water-immersed type aluminum samples. Effect of pulse density in the residual stress field is evaluated. Residual stress distribution as a function of depth is assessed by the hole drilling method. It is observed that the higher the pulse density the larger the zone size with compressive residual stress. Densities of 900, 1350 and 2500 pulses/cm(2) with infrared (1064 nm) radiation are used. Pre-cracked compact tension specimens were subjected to LSP process and then tested under cyclic loading with R = 0.1. Fatigue crack growth rate is determined and the effect of LSP process parameters is evaluated. Fatigue crack growth rate is compared in specimens with and without LSP process. In addition fracture toughness is determined in specimens with and without LSP treatment. It is observed that LSP reduces fatigue crack growth and increases fracture toughness in the 6061-T6 aluminum alloy. (C) 2004 Elsevier B.V. All rights reserved.