Experimental Study of Forming Rene95 Alloy Parts by Laser Cladding

 In this paper, experimental study of forming metal parts by laser cladding Rene95 alloy powder was reported. The influence of main process parameters, such as laser power, scanning speed and laser beam diameter, on the thickness, width and the angle of the laser cladding track was investigated. The microstructures of laser cladding parts were studied and compared with those of common casting parts. The obtained Rene95 metal parts formed by laser cladding are dense and of high strength.
Near Net Shape production of metal components using LENS
Rapid Prototyping and Near Net Shape manufacturing technologies are the subject of considerable attention and development efforts. At Sandia National Laboratories, one such effort is LENS (Laser Engineered Net Shaping). The LENS process utilizes a stream of powder and a focused Nd YAG laser to build near net shape fully dense metal parts. In this process, a 3-D solid model is sliced, then an X-Y table is rastered under the beam to build each slice. The laser 1 powder head is incremented upward with each slice and the deposition process is controlled via shuttering of the laser. At present, this process is capable of producing fully dense metal parts of iron, nickel and titanium alloys including tool steels and aluminides. Tungsten components have also been produced. A unique aspect of this process is the ability to produce components wherein the composition varies at differing locations in the part. Such compositional variations may be accomplished in either a stepped or graded fashion. In this paper, the details of the process will be described. The deposition mechanism will be characterized and microstructures and their associated properties will be discussed. Examples of parts which have been produced will be shown and issues regarding dimensional control and surface finish will be addressed.
Directed light fabrication of iron-based materials
Directed light fabrication (DLF) is a process that fuses gas delivered metal powders within a focal zone of a laser beam to produce fully dense, 3-dimensional metal components. From a computer generated solid model, deposition ``tool paths`` are constructed that command the laser movement to fabricate near net shape parts a layer at a time. Among potential candidate systems to study, iron-based alloys are particularly attractive for rapid prototyping. To evaluate the processing parameters in the DLF process, studies have been performed on the microstructural development in 1-dimensional and 2-dimensional Fe-based components. For example, continuous microstructural features are evident, implying a continuous liquid/solid interface during processing. In addition, solidification cooling rates have been determined based upon secondary dendrite arm spacings in Fe-25wt. % Ni and 316 stainless steel. Cooling rates vary from 10{sup 1}{minus}10{sup 5} K s{sup {minus}1}, and the solidification behavior has been simulated using macroscopic heat transfer analyses.