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.
Directed light fabrication of a solid metal hemisphere using 5-axis powder deposition
Abstract Directed light fabrication (DLF) is a direct metal deposition process that fuses metal powders, delivered by gas into the focal zone of a high-powered laser beam, to form a fully-dense metal deposit. Computer-based design and numerical controls are used in conjunction with the metal deposition process to guide the formation of 3D parts. This study demonstrates the ability to directly fabricate complex shapes using a 5-axis DLF machine. As an example, the production of a hemispherical shape is described, with the associated fabrication case study, metallographic examination and part characterization. The deposition of fully-dense stainless-steel components is achieved in all orientations, from horizontal to vertical, and dimensional comparisons between the DLF-deposited shape and the original part definition, illustrates that near-net shape tolerance levels are attainable within a 0.1 mm envelope. The single-step production of fully-dense, near-net shaped, 3D metal parts directly from a computer model is achieved without the use of forming dies, tooling or machining. As a result, significant process flexibility over conventional processing capabilities are recognized, with potentially lower productions costs and higher quality components.
Evolution of carbide precipitates in Hastelloy N joints during welding and post weld heat treatment
Abstract The effects of welding and post weld heat treatment (PWHT) on the morphology, composition and lattice parameter of the precipitates in the welding joints of Hastelloy N alloy have been investigated. Joint samples were prepared using a gas tungsten arc welding process with ERNiMo-2 fillers, and then solid-solution treated at 1100 °C for 20 min. After welding, eutectic M6C carbides can be observed in the heat affected zones (HAZ) and weld zones (WZ). These eutectic M6C carbides become spheroidized during the following PWHT. The concentration of Si decreases during the transformation from the primary ones to eutectic ones, and then increases during the spheroidizing process. The total concentration of Si + Cr in M6C carbides remains stable during welding and PWHT. At the same time, the heat leads to the outward diffusion of Mo from the M6C carbides, which results in a decrease of the lattice parameter.