In this work, the authors employ computer modeling to investigate a quenching process recently demonstrated at Karlsruhe Institute of Technology. A matrix of models was run to assess the effects of heat transfer and phase transformation kinetics on residual stress and microstructure in a relatively thick walled tube. The experiments at Karlsruhe were conducted using a high pressure water quench to produce martensite and residual compressive stress in the bore of a 4140 steel tube. Results show that the timing and rate of martensite formation and bainite kinetics have a significant effect on both the in-process and residual stress state.

Rene 65 is a nickel-based superalloy used in aerospace components such as turbine blades and disks. The microstructure in the as-received condition of the superalloy consists of about 40% volume fraction of gamma prime precipitates, which is so strong that thermomechanical processing is problematic. The aim of this work is to find a heat treatment to reduce hardness for manufacturing purposes without changing grain size in the final application. For the design of the heat treatments, Taguchi’s L8 matrix is used and the factors that are examined include cooling rate, hold temperature, hold time, and cooling method to room temperature.