Effects of heat treatment on mechanical properties of modified cast AISI D3 tool steel

• Secondary hardening occurred when tempered at 500 °C and austenitized at 1050 °C.
• Hardness of new steel is about 1 HRC higher than D3 steel, when tempered at 300 °C.
• New steel has less bending strength and strain compared with D3 steel.
• With increasing hardness wear resistance is improved about 56%.
• Linear relationship observed between weight loss and hardness of modified steel.

In this research new modified as-cast cold work AISI D3 tool steel was produced by increasing Ti and Nb and decreasing Cr. At first, Cast samples were homogenized at optimized cycle and then austenitized and tempered within the specified temperature ranges. Mechanical properties and wear behavior were determined by performing hardness test, three point bending test and pin on disc wear test. Also, scanning electron microscope was employed to characterize the new modified steel.For the specimens austenitized and tempered at 1050 °C and 500 °C respectively, the secondary hardening effect was observed which was consistent with lower weight loss of pin on disc wear test results. The results show that, the new modified as-cast steel represents hardness and wear resistance equal to or better than that of standard wrought D3 steel, while its strength and toughness are lower than those of wrought steel.

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