AISI H13工具鋼氮氧化/TiAlN多重表面處理後熱熔損、腐蝕及磨耗性質之研究

Abstract

AISI H13 tool steels are almost exclusively used on extrusion and die-casting dies. They are characterized by high strength, ductility, good tempering resistance, and moderate cost. Thermal fatigue and erosion are the most important factors limiting tool life and resulting in the tool failure of hot work tool steels. A surface treatment is usually used to increase wear resistance as well as to improve corrosion resistance. The oxynitriding process uses air or steam at the end of the nitriding stage; used as an oxidizing medium, it is an integral part of the treatment. In addition, the TiAlN coating has high strength and thermally stable properties resulting from the cathodic arc PVD treatment; therefore, the oxynitriding/TiAlN duplex is used to treat AISI H13 tool steel in an attempt to increase tool life. In this study, the specimens were subjected to various surface treatments including oxynitriding, TiAlN coating, and oxynitriding/TiAlN duplex treatments. In order to investigate the molten loss for melting A390 aluminum alloy, wear resistance and corrosion resistance for different surface treatments were examined. XRD, SEM and OM microstructural inspections, erosion, wear and corrosion tests were performed. The experimental results indicated that a 0.03-0.04 mm oxynitride layer and a 3-4μm TiAlN thin film could be obtained after the oxynitride/TiAlN complex treatment. This duplex treatment had the highest surface hardness (Hv0.01 3463); thus, the wear behavior results showed both higher hardness and a lower wear volume (0.05 mm3). Moreover, the higher hardness and high thermally stable properties of the oxynitride/TiAlN duplex layer were found to have the most effective erosion resistance. The corrosion test results also showed the duplex layer to have the optimum corrosion currents of 9.64 × 10-5 and 4.42 × 10-6 A in 0.15 M HCl and 3.5 wt% NaCl solutions, respectively, signifying that the complex treatment resulted in the best corrosion resistance.