A Complete System for Testing and Evaluation of Quenchants and Quenching Systems

Abstract

The quenching operation is a very critical part of the heat treatment process. Improper quenching parameters and drifting of the cooling characteristics during the working life of the quenchant will influence the quenching results. Sophisticated computer-based tools have made it possible to monitor, evaluate, and perform a continuous quality control of the quenchants’ and the quenching systems’ performance. The increasing and ever more sophisticated use of FEM simulation in order to optimize products and processes means that there is also a growing need for accurate input data. In quenching simulations, the boundary conditions expressed as heat transfer coefficients based on measured cooling curves are of great importance in order to obtain accurate calculations. One system that offers these features is the ivf SmartQuench® system (SQ).4 This system encompasses data acquisition and a software module for analyzing the cooling curves. With the new, extended software module that was introduced in 2007, SQintegra (SQi),4 it is now possible for the user to calculate heat transfer coefficients (e.g., for the ISO 9950 probe), as well as hardness and microstructure in a cross section of steel samples. Heat transfer calculations are made on the basis of an inverse analysis of the recorded cooling curve. The result is used as input for the calculation of microstructural constituents and the hardness profile of cylindrical samples of arbitrary diameter. Calculations can be made for several different steel grades. The system can be used for quality control of quenchants, troubleshooting, process follow-up, calculation of heat transfer coefficients, hardness calculations compared to verifying tests, and sensitivity analyses of quenchants. The system has also been used to evaluate the cooling performance in showers used for quenching after induction heating. The process window for a specific quenching shower was established for a polymer quenchant. Factors considered were flow rate, concentration and temperature of the quenchant.