Effect of Surface Coatings on the Service Life of Unimax Casting Tool Steel

Abstract:

The tool steel materials are expensive this is the reason why the lifetime increase is a goal of the production technology. The tool life is determined by the various complex mechanical, thermal, chemical, and tribological properties. Tools properties depend on the chemical composition and their microstructure. The microstructure depends on the chemical composition, the production process, the heat treatment and surface treatment technologies. The goal of this research was to increase the service lifetime of the casting mould tool. It was prepared and investigated four kinds of test specimens. The first kind of specimen was made from conventional steel (W302). It was made an austenitization (1020°C) and was cooled with 9 bar nitrogen gas to 40°C and kept for 6 minutes. The quenching was followed with three times tempering processes (570°C, 580°C, 560°C) in 2 bar N₂ gas. The second kind of test specimen was made from Unimax electro-slag remelted steel (ESR). It was made an austenitization (1020°C) and was cooled with 9 bar nitrogen gas to 40°C and kept for 6 minutes. After quenching the process continues with three times tempering (610°C, 620°C, 600°C). The third kind of test specimen Unimax a electro-slag remelted steel (ESR), to which firstly an austenitization (1020°C) was made, quenched in nitrogen gas with 9bar and then cooled in liquid nitrogen till minus 150°C. After cryogenic treatment, the process continues with three times tempering (610°C, 620°C, 600°C). The fourth kind of specimen was made by the same process as the second and after it a PVD coating process was made to coat the surface by a TiBN layer. It investigated the hardness and wear resistance of all heat-treated and surface-coated steel specimens. The comparative wear resistance testing was investigated by a ball cratering tester. The rank of the tested specimen was the next: the lowest wear resistance measured in the case of the heat-treated W302, the middle in the case of cryogenic heat-treated Unimax and the highest wear resistance earned in the case of the PVD-coated Unimax. The results of the investigations proved that the Unimax tool steel service lifetime can increase better than the conventional tool steel by heat treatment and surface treatment. The practice certified that the surface-treated Unimax tools' service lifetime is much longer than the conventional ones.

• Periodical: Advanced Engineering Forum (Volume 53)
• Pages: 11-18
• DOI: https://doi.org/10.4028/p-G8p2X1
• Online since: December 2024
• Authors: László Tóth*, Enikő Réka Fábián, Zoltán Nyikes, Ion Aurel Perianu, Tünde Anna Kovács
• Keywords: Cryogenic Treatment, Hardness, Microstructure, PVD Coating, Service Life Time, Unimax Tool Steel, Wear Resistance

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