Erosion and Abrasion Resistance of Boride and Carbide-Based Weld Overlays

Abstract

Abstract WELD OVERLAYS, more specifically chromium carbide weld overlays, have been widely used as thick coatings to protect critical plant components from abrasion wear. These thick coatings have been also considered in applications involving severe erosion, their thickness being synonymous with long life protection. Recently, boride-based arc-sprayed coatings have been developed especially for erosion control. They have demonstrated their superiority in erosion resistance over various coatings including chromium carbide submerged arc overlays. This work was undertaken to produce dense boride-based coatings comparable in thickness with carbide-based overlays. A GMAW (Gas Metal Arc Welding) welding procedure was developed for depositing boride-based overlays from cored wires. A comparative evaluation of the hardness, erosive and abrasive wear resistance of these boride-based overlays with regards to chromium and tungsten carbide overlays was carried out. Abrasion and erosion wear testing demonstrated that boride-based overlays showed higher abrasion and erosion resistance than chromium and tungsten carbide-based overlays. Overlays with higher wear resistance can be obtained if appropriate welding procedure is used to decrease weld bead dilution and therefore increase coating hardness. Results also showed that boride-based coatings deposited by arc spraying posses higher erosion resistance than those produced by the welding process.