摘要
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 austenitic stainless steel sheet S20400 coated with ethyl-silicate black japan was shocked using the laser with 1. 054 μm output wave length and 20 ns short pulse. The macroscopic deformation, their microscopic structures and the appearance change of the sheets were observed with the thermo-field emission scanning electron microscope. The experimental results indicate that the plasma detonation wave acting on the sheets＇ surface in laser shock processing can induce obvious deformation when the laser facula is 7 mm diameter and the energy density is 2 GW · cm ^-2 The microscopic morphology observation reveals that the condensed plasma forms a magma-like shell, which guarantees the shocking effects of the laser beam; the detonating wave of plasma has a slight ablative effect on the very superficial of the specimens, but no harm to the forming quality. The macroscopic deformation mechanism belongs to the uniform plastic deformation, but in the microscopic mechanism, the dominant changes express in twin deformation, slipping and stacking faults in austenite grains. The negative effect of grain boundaries on the plastic deformation during laser shock processing is discussed.
出处
《金属热处理》
CAS
CSCD
北大核心
2008年第10期63-67,共5页
Heat Treatment of Metals
基金
国家自然科学重点基金(50735001)
关键词
激光制造
激光冲击形变
奥氏体不锈钢
塑性变形
微结构
laser manufacturing
laser shock forming （LSF）
austenitic stainless steel
plastic deformation
microscopic structure
