engleski

Workshop Designed System for Quenching Intensity Evaluation and Calculation of Heat Transfer Data

Computer simulation of a quenching process that aims to predict precisely the resulting microstructures and the hardness distribution for components in workshop practice, needs first of all, as input, real and accurate heat transfer data to calculate cooling curves at every arbitrary point of t he cross-section. A system has been developed for quenching intensity measurement, recording and evaluation and for calculation of heat transfer data for all quenchants, different quenching conditions and different quenching techniques. The main part of the hardware is the LIŠČIĆ-NANMAC cylindrical probe instrumented with multiple thermocouple assembly. Based on the TEMPERATURE GRADIENT METHOD the system enables to calculate and graphically present the heat flux on the surface of the probe during the whole quenching process. As an example, which conclusions can be drawn from it, an investigation of the influence of polymer-solution (PAG) concentration is presented. By using another software module "PROBE", calculation of the real, temperature dependent heat transfer coefficient on the probe surface is possible. This heat transfer coefficient together with the surface temperature measured by the probe, enable calculating the cooling curves a t every arbitrary point of the round bars cross-section. Examples for quenching in oil and in a polymer-solution (PAG) of high concentration are given. If, instead of the temperature dependent heat transfer coefficient, a constant (average) value of it is used for cooling curves calculation, the accuracy of such calculation is substantially decreased, as it is shown by error functions that are compared to measured temperature-time data.

Steels; Quenching Intensity Measuring; Evaluation and Calculation of Heat Transfer Data

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