Circular economy practice: From industrial metal waste to production of high wear resistant coatings

Abstract

Recently, recycling has become an essential issue in the industrial sector due to the soared consumption of materials and energy. One of the few possible ways to recycle metal waste is re-melting and converting the waste to new products. However, it requires a lot of energy, causes environmental contamination and is not applicable worldwide. Landfilling is no longer an option. This research paper focuses on finding an alternative way to recycle industrial waste by using the Submerged Arc Welding method (SAW) and metal waste, what is collected by manufacturing companies, in order to produce wear resistant hard-facings. When selecting metal waste, the greatest attention was given to waste of alloys with carbide forming elements. Turnings, shavings, and chips, as well as debris of high speed tool steel (HS6-5-2), ledeburitic high chromium cold work steel (X210Cr12), cast iron chips, waste of boron carbide B4C, worn grinding wheels (SiC), sintered hardmetal (H123, HG30) all were chosen as the remedy for reinforcement. Five possible compositions of above mentioned waste were discussed and tested on wear. SAW technique with properly chosen parameters: current 180–200 A, voltage 22–24 V, travel speed – 14.4 m/h was adapted for the production of hard-facings. Two methods to introduce waste metal powder to the weld zone were utilized: spreading of powder over the surface of substrate, and mixing with standard flux. Hard-facings obtained from waste materials were tested on abrasive emery wear. Volume-wear loss in most cases was compared to commercial steel grades. Wear results confirmed expectations as wear resistance of waste based hardfacings ∼2 times exceeded the wear resistance of commercial alloys.