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蓝光激光定向能量沉积纯铜零件的工艺及性能

Process and performance of pure copper parts formed by blue laser directed energy depostion

  • 摘要: 金属高反材料对短波长激光拥有较高的吸收率,文中使用大功率蓝光激光器作为能量源在不锈钢基板上进行纯铜的沉积,将激光功率、扫描速度和送粉速率从5个水平形成不同的工艺参数组合进行全因子试验. 先从宏观尺寸分析了工艺参数对沉积层的影响,后从相对密度、组织结构和力学性能3个方面对多道多层工艺进行探究. 结果表明,单位送粉激光能量(laser energy per unit powder feed,LEPF)在2.592 ~ 6.048 kJ/g范围内可进行稳定的连续沉积,而当LEPF值大于6.050 kJ/g时,因用于沉积的激光能量过多而导致气孔出现. 使用LEPF值为4.53 kJ/g打印出了表面质量较好的纯铜薄壁圆筒零件. 通过正交扫描得到最高相对密度为99.10%的纯铜块状样件,并观察到了两种孔隙:近球形的气体包封孔隙(I型)以及未熔合和未熔化的粉末孔隙(II型). 最后进行拉伸测试,从结果发现,远离基板成形位置抗拉强度为196.55 MPa,靠近基板成形位置的断后伸长率为26.72%.

     

    Abstract: High reflective metal materials have high absorptivity to short wavelength laser. In this paper, high-power blue laser is used as energy source to deposit pure copper on stainless steel substrate. The laser power, scanning speed and powder feeding rate are combined to form different process parameters on five levels for full factor test. Firstly, the influence of process parameters on the deposition layer was analyzed from the macro dimension, and then the multi-channel and multi-layer process was explored from the three aspects, including relative density, microstructure and mechanical properties. The results showed that continuous deposition can be performed when the laser energy per unit powder feed (LEPF) is in the range of 2.592 ~ 6.048 kJ/g. When the LEPF value is more than 6.050 kJ/g, the pores appear due to the excessive laser energy used. The pure copper thin-walled cylindrical part with good surface quality was printed with LEPF value of 4.53 kJ/g. Pure copper bulk samples with the highest relative density of 99.10% were obtained through orthogonal scanning, and two kinds of pores were observed: near spherical gas encapsulated pores (type I) and unfused powder pores (type II). Finally, tensile tests were carried out, and the results showed that, The tensile strength far from the base plate is 196.55 MPa, and the elongation after fracture near the base plate is 26.72%.

     

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