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利用输出波长为1.054μm、脉冲宽度为20ns的激光,对表面涂覆硅酸乙酯吸收涂层的S20400锰奥氏体不锈钢板料进行了激光冲击形变,用热场发射扫描电镜观察分析了激光冲击后钢板的微结构及其形貌的变化。试验结果表明,在激光冲击光斑直径为7mm、功率密度为2GW.cm-2的情况下,作用于钢表面的等离子爆轰波能有效地对不锈钢试件实施形变。微观形貌观察表明,激光冲击后的等离子体冷凝形成岩浆状硬壳,保证了激光冲击的力效应;等离子爆轰波对不锈钢试样表面有轻微的烧蚀效应,但不影响成形质量;不锈钢激光冲击的宏观形变机制为均匀塑性变形,微观机制以奥氏体晶粒内的机械孪晶、滑移和层错为主,晶界对激光冲击形变有负效应。
The laser-induced deformation of S20400 manganese austenitic stainless steel sheet coated with ethyl silicate absorption coating was carried out by laser with output wavelength of 1.054μm and pulse width of 20ns. The laser beam was observed by thermal field emission scanning electron microscope Microstructure and morphological changes of steel plate after impact. The experimental results show that the plasma detonation wave acting on the steel surface can effectively deform the stainless steel specimen under the laser shock spot diameter of 7mm and the power density of 2GW.cm-2. The microscopic observation shows that the plasma after laser shock condensation forms a magma shell, which ensures the laser effect. The plasma detonation wave has a slight ablation effect on the surface of stainless steel sample, but does not affect the forming quality. The stainless steel The macroscopic deformation mechanism of laser shock is uniform plastic deformation. The micro mechanism is dominated by mechanical twists, slippings and faults in the austenite grains, and the grain boundary has a negative effect on laser shock deformation.