One of the most critical parts of the heat treatment process, and usually the least controllable one, is the quenching operation. Improper selection or application of a quenching medium, or a drift in its cooling characteristics during its lifetime, may result in products that do not meet specifications and therefore give rise to substantial additional costs for e.g. straightening, rework, rejection, delayed deliveries and, sometimes, lost goodwill for the heat treater. A greater awareness of the importance of the quenching process came with the introduction in the last couple of decades of ISO and ASTM standards for testing cooling media (hardening oils and polymers), and commercial instruments for testing compliance with these standards. In 2003, a new, advanced system – ivf SmartQuench – was introduced which has three main features: a small, handheld data acquisition unit, advanced computer software and wireless data transmission between the data acquisition unit and the computer. The design facilitates in-situ testing in quench tanks and testing in laboratories. Recently, this system has been extended with a unique software module that allows calculation of heat transfer coefficients (e.g. for the ISO 9950 probe) by the inverse method, and calculation of hardness and microstructure in a cross-section of steel samples.
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.
Résumé Cet article présente les résultats d’un exercice de négociation à distance mené à l’automne 2002 entre des groupes d’étudiants de l’École de Commerce et d’Économie d’Umeå (USBE) en Suède et ICN, école de management en France. Il décrit le cas et ses objectifs, il présente les groupes d’étudiants, la situation de l’exercice et la méthode utilisée pour jouer le cas de négociation. Il comprend également des données collectées pendant et après le cas, comme une analyse de documents écrits et de la perception mutuelle des négociateurs. Des éléments particuliers comme le sens des mots ou encore le temps de réaction des négociateurs, sont ici signifiants pour les joueurs et sont mis en évidence. Il se termine par des commentaires à propos des apprentissages dus à l’exercice, et des recommandations pour des exercices futurs.
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