Induction and Furnace Tempering of 30mm diameter 4140 steel rods – a comparison of the microstructural development and the skin effect

As part of a continuing program to compare a 4140 steel’s response to induction tempering to furnace tempering, a series of experiments has been conducted to compare the tempering behavior of induction hardened 30 mm rods with a 3 mm case depth. The induction hardened rods were induction tempered or furnace tempered to the same hardness. This initial report will compare the microstructures and microhardness profiles of the tempered rods. Previous results on 5mm rods have shown similar tempering behavior with only minor variations in the Holloman-Jaffe constant. The results of induction and furnace simulations will also be presented.