Sang Yuxin, Xiao Muzheng, Zhang Zhijing, Su Jiangzhou
School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China.
Beijing Hangxing Machinery Manufacture Limited Corporation, Beijing 100013, China.
Materials (Basel). 2022 Jul 14;15(14):4916. doi: 10.3390/ma15144916.
Beryllium is widely used in the manufacturing of precision instruments because of its high thermal and mechanical properties. However, because beryllium is expensive, and processing it generally uses subtractive manufacturing methods, the cost is high, the utilization rate of cutting the materials is low, and the processing is difficult. Additionally, it is extremely prone to cracking, brittle fracturing, and fracturing during the machining process. In this paper, a new method for manufacturing beryllium laser additives under a pressure atmosphere is proposed. Via the single-point and single-pass laser melting of beryllium materials in an inert gas (Ar) pressure atmosphere, the results of the experiments conducted in the pressure range of 1 to 30 bar indicated the following: (1) beryllium can absorb the laser and form a molten pool, and the contour area of the upper surface of the molten pool is approximately 80% of that of 304 stainless steel under the same energy input; (2) severe oxidation occurs on and near the molten pool surface under low pressure, and oxidation is eliminated when the pressure is increased; (3) as ambient pressure increases, the surface profile of the molten pool gradually exhibits an irregular shape, and the cracks on the surface of beryllium change from "divergent" to "shrinkage", which can eliminate cracking. At higher pressures, the "small hole" phenomenon in the molten pool disappears, forming a wide and shallow molten pool shape that is more conducive to stable deposition. The experimental results indicate that the laser-additive manufacturing of beryllium in a pressure atmosphere is a meaningful developmental direction for beryllium processing in the future.
铍因其高热学和力学性能而广泛应用于精密仪器制造。然而，由于铍价格昂贵，且加工时一般采用减材制造方法，成本高、材料切削利用率低且加工困难。此外，在加工过程中它极易出现开裂、脆性断裂和破碎。本文提出了一种在压力气氛下制造铍激光添加剂的新方法。通过在惰性气体（氩气）压力气氛中对铍材料进行单点单道激光熔化，在1至30巴压力范围内进行的实验结果表明：（1）铍能够吸收激光并形成熔池，在相同能量输入下，熔池上表面的轮廓面积约为304不锈钢的80%；（2）在低压下熔池表面及附近会发生严重氧化，压力升高时氧化消除；（3）随着环境压力增加，熔池表面轮廓逐渐呈现不规则形状，铍表面的裂纹从“发散型”变为“收缩型”，可消除开裂。在较高压力下，熔池中的“小孔”现象消失，形成宽而浅的熔池形状，更有利于稳定沉积。实验结果表明，在压力气氛下对铍进行激光增材制造是未来铍加工一个有意义的发展方向。
