Session BB6.3

9:15 AM BB6.3
FABRICATION OF 3-D SHAPES BY LASER AIDED DIRECT DEPOSITION OF METALS. Jyoti Mazumder, Karthik Nagarathnam, Joohyun Choi, Center for Laser Aided Intelligent Manufacturing, Univ of Michigan, Ann Arbor, MI; Justin Koch, Caterpillar Inc., Mossville, IL.

Laser Cladding by layers offers the possibility of fabrication of 100% dense metal component, even with graded microstructure and composition. Present computer controlled 5-axis workstations integrated with lasers enable us to fabricate various geometry. Initial work has demonstrated that components with mechanical properties similar to plate materials can be fabricated even from oxide formers such as aluminum in addition to copper, nickel and ferrous alloys including H13. In other words one now can produce a 100% dense metal part in near net shape directly from the CAD drawing. H13 tool steel is one of the difficult alloys for deposition due to residual stress accumulation from martensitic transformation. However, it is the material of choice for the die and tool industry. A pair of functional dies have been fabricated with H13 alloy. Copper chill blocks and water cooling channels were the integral part of the injection molding dies. As deposited surface roughness was found to be similar to that of a cast structure. Best possible resolution for wall thickness using 6kw CO₂ laser so far is around 0.5mm. Thinnest deposition up to 25$\mu$m has been achieved so far using Nd-YAG laser. It is already demonstrated that wide range of deposition rate and geometrical resolution may be possible with laser based DMD as a function of the laser power and beam quality. This paper describes the properties and microstructure of materials produced by Laser aided direct metal deposition technique.