Solidification in direct metal deposition by LENS processing

Thermal imaging and metallographic analysis were used to study Laser Engineered Net Shaping (LENS(TM)) processing of 316 stainless steel and H13 tool steel. The cooling rates at the solid-liquid interface were measured over a range of conduction conditions. The length scale of the molten zone controls cooling rates during solidification in direct metal deposition. In LENS processing, the molten zone ranges from 0.5 non in length to 1.5 mm, resulting in cooling rates at the solid-liquid interface ranging from 200-6,000 Ks(-1).