Surface modification of s235 steel, molybdenum, and tungsten using electron beam scanning and electric discharge machining

Abstract

The process of surface modification of structural steel s235, molybdenum, and tungsten samples was carried out using two techniques—high-energy electron beam line scanning in a vacuum in a device used for electron beam welding and electric discharge machining (EDM), in which samples are submerged in the dielectric fluid. Elemental surface distributions were then examined using two spectrometric techniques: secondary ion mass spectrometry (SIMS) and glow discharge mass spectrometry (GDMS). Samples were also examined using scanning electron microscopy with energy dispersive x-ray analysis (EDX). SIMS, GDMS, and EDX data show the segregation of manganese out of the electron beam scan line at the surface of s235 steel. In the case of EDM machined s235 steel, no surface segregation of manganese is seen, while the line treated with this machining is enriched in hydrogen, carbon, and copper, as contaminants of the dielectric fluid (kerosene) and the copper electrode are used. The SIMS data for tungsten show that the electron beam cleans up the impurities, while the EDM technique adds them. The data for molybdenum show that the electron beam cleans the surface of hydrogen and iron while enriching it with sodium and potassium. EDM-treated molybdenum appears to be contaminated with carbon and potassium but detects lower levels of hydrogen, sodium, and copper than the untreated surface.