Achieving Uniform Tempering Temperature using Simultaneous Induction Heating and Water Spray for Steel Tubes

Abstract High quality steel tubes are often quench hardened for superior mechanical properties, and the process includes austenitizing, spray quenching, and tempering. During spray quenching, the cooling rate is affected by the type of quenchant, nozzle design, flow rate, spray zone and spray time. In this paper, the hardening process of steel tubes made of AISI 4140 is designed by using DANTE, a commercial finite element heat treatment simulation software. The hardening process includes austenitizing by induction heating, spray quenching by water nozzles, and tempering by using an innovative induction heating with simultaneous water spray cooling. The modelling results include final hardness, metallurgical phase transformations during processing, in-process stresses and residual stress state, and distortion. Tempered martensite is the final microstructure phase of the tube in this case.