Influence of both hardfaced and nitrided layers on the durability of hot forging tools

This paper presents the results of preliminary operational tests of forging dies made with a new hybrid technology combining the self-shielded arc surfacing (hardfacing) and gas nitriding operations. Heat-treated and nitrided tools as well as hardfaced tools were tested as a reference. Dies were used for a similar number of forging cycles and then withdrawn from production and analyzed. Analysis covered the measurement of wear geometry using a three-dimensional scanner, macroscopic tests, microstructure study, microhardness analysis and observations under scanning electron microscopy. Test results indicate a beneficial effect of the new technology’s application, since elevated resistance to fatigue cracking and abrasive wear was demonstrated. Results were compared with reference tools prepared by only hardfacing or only nitriding, which were less resistatnt, of which nitriding brought more resistance to wear than hardfacing. These preliminary studies justify further studies leading to the development of this new technology for surface layer treatment of forging tools by hardfacing combined with nitriding.