Wear of potential tool materials for aluminium alloys friction stir welding at weld temperatures

摘要

Friction stir welding is a solid-state joining process that uses a non-consumable tool to join materials by mixing themmechanically in the weld area instead of melting them. The high-quality friction stir welding (FSW) process temperatures are inthe range of 400–500 °C. Adhesive wear is suggested to be the main wear mechanism for the FSW tool. Adhesive wear testingshould be performed at the weld temperature or close to the welding process temperatures for better simulation of real-life FSWtool wearing conditions. Adhesive wear tests of three FSW tool materials, WC–Co and TiC based with NiMo and FeCr binders attemperatures of 70 °C (low) and 400 °C (high) were performed by turning aluminium alloy AW6082-T6. The higher temperaturein the cutting zone was achieved by increasing the cutting speed. To measure the temperature at the interface of the cutting tooland the workpiece, a novel method based on the thermoelectric effect was used. The wear was determined as the change of thegeometry of the cutting edges of the tool. Microscopic investigations were performed by using scanning electron microscopy. Thedistribution of chemical elements and the chemical composition of the tool cutting edge were analysed by energy dispersive X-rayspectroscopy. The TiC-based cermets (TiC–NiMo and TiC–FeCr) demonstrated superiority over WC–Co cemented carbideat both low (70 °C) and high (400 °C) temperatures. The highest wear performance at the low temperature was shown by theFe-alloy bonded composite TiC–FeCr while at the high temperature the Ni-alloy bonded cermet TiC–NiMo had the highest wearperformance.