Zn22Al4Ag ALLOY MICROWIRES CASTING TO RAPID SOLIDIFICATION PROCESS BY ROTATING DRUM

In this work, the Zn22Al4Ag alloy was synthesized by melting in a muffle furnace.The alloy obtained was characterized by Scanning Electron Microscopy Energy Dispersive Spectroscopy and was analyzed by the X-Ray Diffraction technique, where the crystallinity of the material was verified before and after being processed. Likewise, the Differential Scanning Calorimetry technique was used to obtain the temperatures where phase transformations occurin the alloy. These results were fed to the Termocalc®, software to numerically obtain the phase diagram of the alloy. Subsequently, a section of the ingot was taken to the rapid solidification process by rotating drum. The process variables were manipulated: jet stability, nozzle diameter, distance from the nozzle surface to the cooling medium, the delay time of the molten material in the crucible, speed of the rotating drum and jet angle, until obtaining a microwire with a diameter of ~ 160µm. Finally, it was determined that inadequate control of these parameters can result in powders, flakes or blockage of the crucible outlet. Potentially uses within the micro and nanoworld as an analogy to structural elements and electrical conductors, in addition to its current use as a coating anti-corrosive. Key Words: ZnAlAg alloy, Melt spinning process, Microwire, DSC analysis, Thermodynamic simulation

Resistance spot welding of additively manufactured maraging steels Part I: Nugget formation

Application of additively manufactured steels is unavoidably involved in the resistance spot welding with conventionally manufactured steels. However, the microstructural evolution of an additive manufactured steel at high temperatures is still unknown, especially for the rapid solidification process. This paper investigated the microstructural evolution of a selective laser melted maraging steel during the rapid solidification process via resistance spot welding. Asymmetrical fusion zone with boat shape was found in the spot weld due to the rougher surface and larger electrical resistance of maraging steel via selective laser melting process. The rapid expansion of fusion zone at end of welding process was caused by the carbide formation at the heat-affected zone of maraging steel via selective laser melting process. Besides, printing orientation affected the surface roughness of a selective laser melted maraging steel and subsequently significantly influence the early stage of formation of fusion zone of additively manufactured maraging steel. We expect that our findings will pave the way to the future application of additively manufactured steels in the industries.