太空作为军事发展和科技发展的制高点，是近年来世界各国激烈竞争的重要领域，如何实现高效、可靠、低成本太空制造，对于我国空间战略具有十分重要的意义。增材制造是实现太空直接制造的重要潜在手段，但目前主流的金属熔丝增材制造技术存在设备体积大、制造成本高、成形能耗高等问题，难以满足太空条件下小空间、低成本和低能耗等要求。基于目前存在的问题，本研究从热源入手，基于焦耳-楞次原理，提出一种真空环境下焦耳热熔丝增材制造的新方法，并进行了单道单层和单道多层的工艺实验研究，该研究将为太空金属增材制造技术前期在地面验证实验提供理论依据和数据支撑。

      首先，基于焦耳热熔丝增材制造基本原理，设计了焦耳热熔丝增材制造打印头等关键结构，研制了圆柱形亚克力真空箱，自主搭建并改进了焦耳热熔丝增材制造实验平台，结果表明：改进后的实验平台提高了能量利用率，降低了设备的成本，为小体积、低成本和低能耗的金属增材制造提供一个新发展方向。

      然后，开展了304不锈钢单道单层的成形工艺实验，研究了工艺参数对单道单层宏观形貌、截面尺寸、截面硬度和表面粗糙度的影响，并分析了单道单层的组织。结果表明：随着电流、速度和辊轮的截面宽度的增大，宏观形貌先变好再变差，截面硬度先升高后降低，表面粗糙度先降低后升高。三组工艺参数对实验结果的影响程度：电流>截面宽度>速度。熔合区附近的晶粒尺寸小于其他区域的晶粒尺寸，沿着熔合线附近分布着铁素体。

       最后，开展了304不锈钢单道多层的成形工艺实验，分析了单道多层成形过程中的特点，并研究了工艺参数对单道多层宏观形貌、成形尺寸、截面硬度和表面粗糙度的影响，检测了单道多层的内部质量。结果表明：单道多层的成形过程具有实验和测试的顺序性、丝材轨迹的重合性和缺陷的连续性等特点；电流逐渐增大时，成形宽度和搭接率增大的同时而成形高度在减小；速度和截面宽度逐渐增大时，成形宽度和搭接率减小的同时而成形高度在逐渐增大。随着电流、速度和截面宽度的增大，单道多层的宏观形貌先变好再变差，截面硬度先升高后降低，表面粗糙度先降低后升高。三组工艺参数对实验结果的影响程度：电流>截面宽度>速度；单道多层样件内部不存在气孔、缝隙和裂纹等缺陷。

      As the commanding height of military development and scientific and technological development,space is an important field of fierce competition among countries all over the world in recent years. How to achieve efficient,reliable and low-cost space manufacturing is of great significance to China's space strategy.Additive manufacturing is an important potential means of realizing direct manufacturing in space,but the current mainstream metal wire additive manufacturing technology has problems such as large equipment size,high manufacturing costs high molding energy consumption,etc,which makes it difficult to meet the requirements of small space and low cost under space conditions. Based on the current problems,this study starts from the heat source,based on the Joule-Lenz principle,and puts forward a new method of Joule heat melt wire additive manufacturing in vacuum environment,which will provide theoretical basis and data support for the pre-experiment of metal additive manufacturing technology in space on the ground verification.

       First of all, based on the basic principle of Joule heat melt wire additive manufacturing, the key structures such as Joule heat melt wire additive manufacturing printing head were designed, the cylindrical acrylic vacuum box was developed, and the experimental platform was independently built and improved. the results showed that the improved experimental platform improved the energy efficiency, reduced the cost of the equipment, and provided a new development direction for small volume, low cost and low energy metal additive manufacturing.

         Then,the process experimental study of 304 stainless steel single-channel and single-layer was carried out to investigate the influence of process parameters on the macroscopic morphology,cross-section size,cross-section hardness and surface roughness of the single-channel and single-layer,and the microstructure of single-channel and single-layer was analyzed. The results show that with the increase of current,speed and cross-section width of the roller, the macroscopic morphology first gets better and then worse,the cross-section hardness firstly increases and then decreases,and the surface roughness firstly decreases and then increases. The degree of influence of the three sets of process parameters on the experimental results:current > section width > speed. The grain size near the fusion zone is smaller than the grain size in other regions,and ferrite is distributed along the fusion line near the fusion line.

         Finally, the forming process experiment of 304 stainless steel single-channel multilayer was carried out to analyze the characteristics of the single-channel multilayer forming process, and to study the influence of process parameters on the macroscopic morphology of single-channel multilayer, forming dimensions, cross-section hardness and surface roughness, and to test the internal quality of single-channel multilayer. The results show that the forming process of single-channel multilayer is characterized by the sequential nature of experiment and test, the overlapping of wire trajectories and the continuity of defects; when the current is gradually increased, the forming width and overlap rate increase while the forming height decreases; when the speed and cross-section width are gradually increased, the forming width and overlap rate decrease while the forming height gradually increases. With the increase of current, speed and section width, the macroscopic morphology of single-channel multilayer becomes better and then worse, the hardness of section increases and then decreases, and the surface roughness decreases and then increases. The influence of the three sets of process parameters on the experimental results: current > section width > speed; single-channel multilayer samples do not have defects such as pores, gaps and cracks inside.