engleski

A New Probe to Measure and Evaluate the Real Quenching Intensity Based on Temperature Gradients

A new Liscic/Petrofer probe is designed to measure and record the quenching intensity in real industrial conditions. It is a cylinder of 50 mm diameter and 200 mm length, made of INCONEL 600, instrumented with 3 thermocouples (TCs) at the same radius of the cross-section: at 1 mm below surface, at 4.5 mm below surface and at the center, at half the length of the probe. The probe measures the dynamic of heat extraction, which is best represented by the change of temperature gradients. The results of each test are presented in the form of the following 4 diagrams: The recorded cooling time-temperature curves ; The calculated heat transfer coefficient (α) as function of time ; The calculated α as function of surface temperature ; The calculated surface temperature. A series of 26 tests recently performed at the Quenching Research Center (QRC) of the Faculty for Mech. Engineering, University of Zagreb, Croatia, has shown that by using this probe and relevant criteria, distinctive data are obtainable, essential for selection of quenchants and quenching conditions which cannot be obtained by small laboratory test probes. These data can e.g. document the differences between a mineral oil and a vegetable oil, as well as to show the influence of quenchant temperature and agitation.

Quenching intensity; Temperature Gradient Method; Heat transfer coefficient

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