Tainá Pigosso1, Sofia Biscaro Coser1, Guilherme Oliveira Neves1.2, Cristiano Binder1
1Federal University of Santa Catarina, Santa Catarina, Brazil
2Universidad del Bío-Bío, Concepción, Chile
A typical car body contains around 300 stamped parts, requiring approximately 750 stamping dies. Replacing tool steel with cast iron could lead to savings of up to US$ 3 million per car model, owing to lower material costs. However, the die surface wear remains a major challenge. This study proposes a dual-step process to enhance the surface properties of cast iron for automotive stamping dies. A systematic approach combining ThermoCalc® and DICTRA® simulations with experimental validation via plasma technology was employed to model the molybdenum surface alloying. Gray and nodular cast iron specimens were surface-alloyed in a DC 20Ar:80H₂ glow discharge, with low-carbon steel as a reference. The plasma processing parameters were varied, including the output voltage (450–650 V) and the pressure (1–3 Torr). Subsequently, the specimens were plasma-nitrided in an 80N₂:19H₂:1CH₄ gas mixture at 550 °C and 500 V. Microstructural, phase, and chemical analyses were conducted along with topographic and mechanical testing. Surface alloying of up to 2 wt.% Mo, combined with nitriding, resulted in hardness values exceeding 1200 HV due to the formation of reinforcing phases such as molybdenum nitrides (Mo₂N-type) and carbides, such as Mo2C. This integrated computational-experimental approach accelerates process optimization and material design for high-performance coatings, thereby addressing new materials for challenges in the automotive industry.