Influence of welding parameters on microstructure and wear behaviour of a typical NiCrBSi hardfacing alloy reinforced with tungsten carbide

Wear parts which are exposed to severe abrasive conditions must withstand high wear demands. Abrasive loading superposed with impact due to abrasive particles are a dominating wear mechanism restricting lifetime in many different industries, for example mining and farming. In practical application, different welding technologies such as plasma transfer arc (PTA), metal active gas (MAG) and laser are used to form wear resistant materials. The aim of this study is to evaluate the influence of welding parameters on the microstructure and wear behaviour of these wear resistant materials using MAG welding technology. To simulate real field conditions on a lab-scale, tests were performed with a standard ASTM G65 dry-sand rubber-wheel tester (3-body abrasion). In order to investigate impact abrasion, a special impeller-tumbler apparatus was designed and used for wear tests (combined impact and abrasion wear). Wear tests were performed on Ni-based alloys containing large amounts of hard phase.Within this work it was shown that welding parameters such as current intensity and number of layers strongly influence dilution with the base material and furthermore the formation of transition zones between welding layers and overlap zones. Concerning wear behaviour it was found that high content of uniformly distributed tungsten carbides in a metallic matrix show the best behaviour under a condition of pure abrasion, whereas under cyclic impact loading (high energy level) massive breaking of the tungsten carbides results in a high wear regime, compared to martensitic materials which perform best.