Experimental Investigation on Hardness and Thermal Conductivity of D2 Steel Alloyed with Copper

Abstract

High chromium high Carbon tool steel (D2 steel) is widely used for making moldsand dies as it possesses high hardness. The major concern in D2 is that the temperature of the mold increases with number of cycles of operation which is due to the insufficient heat transfer from the mold cavity to the surface. An additional cooling system can be provided to overcome the aforementioned problem but it leads to higher production cost and it complicates the mold design. As the effect of Copper on steels increases thermal conductivity, in the present study Copper is added to D2 in the composition varied in steps of 0.5% up to 2.0%. Specimens were fabricated using gas casting technique and heat treatment (quenching and tempering) was done. As the mold requires high strength, hardness and high thermal conductivity, hardness (Vickers) and thermal conductivity tests were conducted. Hardness test was taken using Vickers hardness testing machine and it was converted to the equivalent HRC and tensile strength. The maximum hardness value of 57.5 HRC was obtained at 2.0% Cu. Similarly, thermal conductivity test was taken and it was observed that maximum thermal conductivity of 25.3 W/mK was obtained at 2.0% of Cu. It was observed that the copper addition increases the thermal conductivity of the D2 steel proportionally. Micro structural analyses were also done and the images were discussed..