Theoretical and experimental investigations of electron beam surface remelting and alloying

Abstract

A central problem in the numerical treatment of melting and resolidification, as well as alloying processes at metal surfaces, is the coupling of the physical phenomena. Among these phenomena, Marangoni convection, conjugated heat transfer, species transport and free-surface deformation occur simultaneously. The involved transport mechanisms take place at different time scales, which enables the decoupling of the governing equations in the solution process. This decoupling procedure has been proven to be capable of computation of metal-surface remelting and alloying processes. In this article, scaling analysis is presented to determine both the time scales and characteristic velocities. Using this information, two-dimensional transient calculations of velocities, temperatures, and species concentration in both liquid and solid phases have been carried out. These theoretical results have been compared with experiments utilizing the high-speed scan deflection technique in electron-beam (EB) surface remelting and alloying of a Ck45 specimen (AISI 1045) with chromium. It was shown that the shape of the resolidified surface is determined by the fluctuation of the vapor pressure. This fluctuation is due to temperature oscillations induced by the transient behavior of the electron beam.

The effect of electron beam surface remelting on the wear behavior of Ti-6Al-4V by EBF3

“…Under the fast cooling rate of the EBSR, a harder and finer B2 phase replaced the dendritic structure. Velde et al [21] investigated the solidification and alloying process of EBSR theoretically and experimentally and proposed theoretical models. However, the influence of EBSR and its parameter on the surface microstructure and properties of titanium alloy manufactured by AM has not been fully understood.…”