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Wire drawing is a tremendously expanding industry which incorporates manufacturing of steel wires having applications in automotive, construction, agriculture, and equipment manufacturing industries. The wire drawing die is usually manufactured from tungsten carbide and cobalt binder, commercially called as cemented carbide.The tungsten carbide die plays a vital role in shaping wires. In this research, we made an effort to improve service life of carbide die from material strengthening perspective. Worn out samples of tungsten carbide dies were collected from reputed wire industry and analysed under FE-SEM to understand their wear behaviour. The as received samples were tested for microstructural analysis under FE-SEM and X-ray diffraction analysis. Wear test and microhardness test was also carried out. Samples were then treated with normalising treatment followed by cryogenic treatment. The cryogenically treated samples were given tempering for 5, 10 and 15 hours and were analysed using the same characterisation tools. Phase analysis showed appreciable decrease in Cobalt binder content of cryotreated specimen tempered for 15 hour, which also showed increase in hardness by 7.6%. Pin-on-disc wear test carried out for cryotreated and tempered specimens simulating the speeds used in wire drawing. Wear test showed an appreciable decrease in wear rate. The dissolution of binder cobalt and stress induced precipitation of carbides is predicted to be the reason behind enhancement of mechanical and tribological properties of the material. Thus, cryogenic treatment with subsequent tempering is a promising heat treatment process to improve wear behaviour and thus the service life of wire drawing dies.
Keywords: Tungsten carbide dies, cryogenic treatment, tempering, wear behaviour
Acknowledgements: Authors would like to acknowledge BEKAERT India for the provision of carbide dies and Physics Department of Smt. Savitribai Phule Pune University for X-Ray Diffraction analysis.