Abstract: High-speed metal particles cold-state impact based additive manufacturing is proposed to solve the problems which widely exist in metal parts free forming process, such as high energy consumption and high thermal residual stress. In the process, high pressure nitrogen (1.5~3.5 MPa) is used to accelerate metal particles and impact into the substrate forming the deposition at room temperature. High-speed impact platform and micronozzle which has both well acceleration performance and high spatial resolution are designed and made. Based on this, process research on accuracy of deposited points and lines are conducted by experiments. Experimental results show that the diameter and thickness of deposited points can be linearly controlled by process pressure while the width and layer thickness of deposited lines can be linearly controlled by process pressure and nozzle’s speed. Moreover, the minimum line width of 0.9 mm is achieved in the experiment to ensure the process sufficient accuracy while line width’s variation of 8% below is achieved to ensure the process sufficient stability. Furthermore, the dense microstructure and high hardness HV0.05 value are observed to ensure the parts good mechanical properties. Effective combination between layers is found to guarantee the ability of the process to manufacture parts layer by layer. Thus the process has been proved to be a stable, controllable and feasible additive manufacturing process.

Key words: additive manufacturing, cold-state manufacturing, fabrication accuracy, high-speed spraying, mechanical property