激光诱导残余应力的试验

Experimental investigation on distribution of residual stress induced by intense laser

对激光诱导残余应力的机理进行了分析研究．用波长1．06μm、脉宽23ns,功率密度10^8～10^9W／cm^2的脉冲激光冲击外形尺寸为30mm×30mm×5．5mm的LY12CZ试样，研究了激光能量密度和冲击次数对残余应力分布的影响，并将激光诱导的残余应力与传统的机械喷丸形成的残余应力进行比较．结果表明：残余压应力随着激光能量密度的加大而加大，残余压应力层的深度随着冲击次数的增加而增加，激光诱导的残余压应力层的深度是传统机械喷丸形成的3～4倍．

Laser shot peening is a novel technique that impresses compressive stress into the surfaces of metals or alloys. In this study, the mechanism of residual stress was investigated, and the experiment of the aeronautic aluminum alloy samples shocked by laser was carried out. The aluminum sample dimension was 30 mm × 30 mm × 5.5 mm. The pulse laser parameters were as following ： wavelength 1.06 μm, duration 23 ns, and laser fluence 10^8 -10^9 W/cm^2. The residual compressive stress induced by laser was compared with that induced by traditional shot peening. The results show that both the magnitude and the depth of residual stress increase with laser fluence and numbers of laser shot. The depth of residual compressive stress induced by laser is three to four times as that induced by traditional shot peening.