Effects of induction hardening and prior cold work on a microalloyed medium carbon steel

The torsional strength and microstructural response to induction hardening of a 10V45 steel with prior cold work was evaluated. The vanadium-microalloyed 1045 (10V45) steel was characterized in three conditions: as-hot-rolled, 18% cold-reduced, and 29% cold-reduced. Two of these evaluations, 10V45 as-hot-rolled and 10V45-18%, were subjected to stationary and progressive induction hardening to three nominal case depths: 2, 4, and 6 mm. All specimens were subsequently furnace tempered at 190 °C for 1 h. The martensitic case microstructures contained residual lamellar carbides due to incomplete dissolution of the pearlitic carbides in the prior microstructure. Torsional overload strength, as measured by maximum torque capacity, is greatly increased by increasing case depth, and to a lesser extent by increasing prior cold work level. Maximum torque capacity ranges from 2520 to 3170 N · m, depending upon induction hardening processing. Changing induction hardening processing from stationary (single-shot) to progressive (scan) had little effect on torque capacity.