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利用Nd∶YAG激光器 ,对 4 0Cr钢进行了激光冲击强化处理。激光冲击强化参数 :激光波长 1 0 6 μm ,脉冲时间为 2 3ns,功率为 16～ 2 0J,功率密度为 2 0GW /cm2 左右 ,光斑直径为 7mm。选用K9玻璃为约束层 ,外形尺寸为 19mm× 4mm ;86 1墨漆为吸光涂层 ,厚度为 0 0 2 5mm。利用HVS 10 0 0显微硬度计和X 35 0残余应力测试仪 ,对 4 0Cr钢激光冲击强化区的显微硬度和残余应力进行了测试 ,结果表明 ,4 0Cr钢经激光冲击强化后 ,强化区表面硬度提高了 30 % ,冲击强化区中心最大残余应力达 - 4 5 0MPa。此外 ,利用H 80 0透射电镜对激光冲击强化区的显微组织进行了观察和分析 ,在强化区显微组织内发现了相变马氏体、初生马氏体和高位错密度
Using Nd: YAG laser, 40Cr steel laser shock treatment. Laser shock enhancement parameters: the laser wavelength of 106 μm, the pulse time of 23 ns, the power of 16 ~ 20J, the power density of 20GW / cm2 or so, spot diameter 7mm. K9 glass is selected as the constraining layer, the outer dimension is 19mm × 4mm; 861 is a light absorbing coating, with a thickness of 0 0 2 5mm. The microhardness and residual stress of laser shock strengthened region of 40Cr steel were tested by using the HVS1040 microhardness tester and the X35 0 residual stress tester. The results show that the 40Cr steel strengthened by laser shock and strengthened Area surface hardness increased by 30%, the center of the impact enhanced zone maximum residual stress of -450MPa. In addition, the microstructure of laser shock-enhanced zone was observed and analyzed by H 80 0 transmission electron microscope. Phase-change martensite, primary martensite and high dislocation density were found in the strengthened zone microstructure.