Free Form Fabrication Using the Laser Engineered Net Shaping (LENS) Process

摘要

Sandia National Laboratories is developing a technology called Laser Engineered Net Shaping (LENS). This process allows complex 3-dimensional solid metallic objects to be directly fabricated from a CAD solid model. Experiments performed demonstrate that complex alloys such as Inconel 625 and ANSI stainless steel alloy 316 can be used in the LENS process to produce solid metallic shapes. In fact, the fabricated structures exhibit grain growth across the deposition layer boundaries. Mechanical testing data of deposited 316 stainless steel material indicates that the deposited material strength and elongation are greater than that reported for annealed 316 stainless steel. Electron microprobe analysis of the deposited Inconel 625 material shows no compositional degradation of the 625 alloy and that 100% dense structures can be obtained using this technique. High speed imaging used to acquire process data during experimentation shows that the powder particle size range can significantly affect the stability, and subsequently, the performance of the powder deposition process. Finally, dimensional studies suggest that dimensional accuracy to ±0.002" (in the horizontal direction) can be maintained.