光纤激光水下切割1mm厚304不锈钢的实验研究

Experimental Research on Fiber Laser Underwater Cutting of 1 mm Thick 304 Stainless Steel

在氩气辅助下,利用光纤激光水下切割1mm厚304不锈钢板。通过切缝平均宽度研究激光功率、切割速度、水层厚度、水体条件等对切割效率及切割质量的影响规律。宏观上,激光功率过低、切割速度过快、水层过厚等因素会降低激光切割效率和质量。在模拟海洋环境的盐水中进行切割试验,水的高盐度和低温大大降低了切割效率。微观上,熔化区、热影响区(HAZ)和基体的组织成分、显微硬度各异,熔化区边缘出现表面形核现象,熔化区晶胞尺寸随着激光能量密度增大而增大;热影响区组织粗大,显微硬度低于基体与熔化区硬度。熔化区边缘硬度达到242.8HV,局部氧化区域硬度高达963HV,是基体硬度的4.3倍;熔化区中部硬度为165.1HV;热影响区硬度为124.6HV,不锈钢基体硬度为223.4HV。

Laser underwater cutting of 1 mm thick 304 stainless steel is demonstrated by a fiber-transmitted laser beam aided by high pressure argon gas. In order to evaluate cutting efficiency and quality via average kerr width, laser underwater cutting is carried out by changing the parameters of laser power, cutting speed, thickness of the water layer, salinity and temperature of the water. On a macro level, lower laser power, faster cutting speed and thicker water layer decrease laser cutting efficiency and quality. Meanwhile, high salinity and low temperature of water decrease laser cutting efficiency as well. On a micro level, metallographic structure and mierohardness of the fusion zone, heat affected zone （HAZ） and substrate are different. Nucleation is detected on the surface of fusion zone. High laser power density promotes crystal grain growth. The microstructure in HAZ is coarse. The microhardness of HAZ is lower than that of the substrate and fusion zone. Microhardness of the outer surface of the fusion zone is 242.8 HV with some oxidized zone showing a hardness of 963 HV, 4.3 times of the substrate. While those of the middle part of the fusion zone, HAZ and substrate are 165.1, 124.6 and 223.4 HV, respectively.