Influence of Rail Metallurgy and Welding Parameterization on the Quality of Flash Butt Welds Done with Mobile Equipment

Abstract

The aim of this study was to assess the impact of rail metallurgy, focusing on segregations and chemical composition, and welding parameterization on the quality and susceptibility of welds to defects and failures induced by mobile flash butt welding (FBW). Ten welds were performed using two different welding programs, with varying heat input, on premium rails sourced from the same batch. The welds underwent full metallurgical characterization of the weld and HAZ, including hardness profile, mechanical testing, and micrographic analysis of the head, web, and foot regions. The results showed that both the HAZ dimensions and the hardness profile are influenced by weld parameterization. All welds fabricated by the lower heat input program, small islands of martensite and retained austenite (MA) were observed only in the foot region, close to the weld line. From the higher heat input program, only one weld showed islands of MA. Localized chemical analysis indicated that the formation of these islands is linked to microsegregation, especially of Mn and Cr present in the rail.

Keywords

• Rail
• steel
• mobile flash-butt welding
• welding parameter