Adjustment of the composition of ASTM D2 tool steel for use in additive manufacturing

• Grant number: 25/01978-1
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2025
• End date: April 30, 2026
• Field of knowledge: Engineering - Materials and Metallurgical Engineering - Physical Metallurgy
• Principal Investigator: Claudio Shyinti Kiminami
• Grantee: Thiago Henrique Basaglia
• Host Institution: Centro de Ciências Exatas e de Tecnologia (CCET). Universidade Federal de São Carlos (UFSCAR). São Carlos , SP, Brazil

Abstract

Tool steels are materials designed for shaping and machining other materials, characterized by high hardness and durability under severe service conditions. Their composition is based on alloys rich in carbide-forming elements such as chromium, molybdenum, tungsten, and vanadium, which enhance wear resistance. Cold-work tool steels from the ASTM D series, particularly D2 steel, have high carbon and chromium content, providing excellent hardness and wear resistance, making them widely used in the manufacturing of polymer injection molds in the automotive industry. However, additive manufacturing (AM) of these materials, especially through the Laser Powder Bed Fusion (LPBF) process, presents significant challenges due to crack formation. D2 steel is prone to both solidification (hot) and cold cracking, exacerbated by residual stresses generated during rapid cooling and the austenite-to-martensite phase transformation. Strategies such as preheating the substrate can mitigate these issues but increase process complexity and reduce productivity. Given this scenario, the present study aims to adapt the composition of ASTM D2 tool steel for its application in AM, minimizing its susceptibility to crack formation. To achieve this, thermodynamic calculations will be performed to adjust the solidification range, the liquid fraction at the end of solidification, the formed phases, and the material's thermal conductivity. Based on these results, candidate compositions will be selected, melted using an electric arc furnace, and subsequently laser remelted to simulate the thermal conditions of the LPBF process. This approach will enable a practical assessment of the candidate alloys, identifying those with a lower tendency to crack formation. The remelted samples will be characterized using optical and scanning electron microscopy, X-ray diffraction, and Vickers hardness testing. The integration of theoretical and experimental results will facilitate the determination of the most suitable composition for application.