SVIBOR - Project code: 2-08-186


Strossmayerov trg 4, HR - 10000 ZAGREB
tel.: +385 1 459 44 44, fax: +385 1 459 44 69


SVIBOR - Collecting Data on Projects in Croatia

Project code: 2-08-186


Main researcher: LIŠČIĆ, BOŽIDAR (57402)

Type of research: applied
Duration from: 04/30/91. to 04/30/95.

Papers on project (total): 10
Institution name: Fakultet strojarsva i brodogradnje, Zagreb (120)
Department/Institute: Department of materials science FACULTY OF MECHANICAL ENG. & NAVAL ARCHITECTURE Ivana Lucicća 5, 10000 ZAGREB
Address: Ivana Lucića 5
City: 10000 - Zagreb, Croatia
Phone: 385 (0)1 512-135
Fax: 385 (0)1 514-535

Summary: This system includes adequate hardware and software for: measurement, recording and evaluation of the cooling (quenching) intensity in heat treatment, especially when hardening steels in real industrial conditions. The main part of the hardware is the LIŠČIĆ - NANMAC probe instrumented with three thermocouples for measurement of temperature at the very surface, below the surface and in the center of the 50 mm Dia bar cross-section. Based on the own Temperature Gradient Method the computer aided program calculates and displays graphically: the course of the heat flux density as a function of time and a function of the probe's surface temperature as well as the course of the temperature difference between the center and the surface of the probe. Using the following criteria: - qmax = maximun heat flux density - tqmax = time from start of quenching upto the moment when qmax occurs - Tqmax = surface temperature of the probe at which qmax occurs - int from t0 to tx (q dt) = integral below the heat flux density curve in a certain time interval, every quenching process for every quenchant, every quenching conditions, and every quenching technique may be evaluated realistically and compared with another quenching or cooling process in respect of: resulting dept of hardening, thermal stresses and the susceptibility to deformation and cracking when hardening. Additional program modules enable the calculation of the course of heat transfer coefficient by using of which calculation of cooling curves is possible at arbitrary points of the cross-section of long cylindrical parts of different diametars and plates of different thicknesses. By superimposing of the calculated cooling curves onto the CCT diagram of the relevant steel, prediction of structural constituents and resulting hardness after quenching is possible.

Keywords: Heat Treatment, Cooling/Quenching, Computer Modelling

Research goals: Objectives and expected contribution of this work are the following: - To test the universality of the described system and method i.e. the possibility of its application to different quenching media (oils, aqueous polymer-solutions, hot salt-baths), to different quenching conditions (bath temperatures, agitation rates), and different quenching techniques (direct quenching, martempering). - To verify the criteria for evaluation of the quenching intensity for different quenching media and quenching conditions in respect to depth of hardening. - To elaborate a computer program for PC with all necessary modules, supplement existing data files with experimental data, and to create a data file of CCT-diagrams for different steels. - To compare the measured and calculated surface temperatures of the probe. The expected contribution of this work from one side is the creation of the computer aided system for measuring, recording and evaluation of the quenching intensity that is universally applicable in different quenching conditions in the heat treatment practice, and from the other side development of methods for modelling (prediction) of structural constituents and hardness after hardening.


  1. Name of institution: Prirodoslovno-matematički fakultet (Matematički odjel) Sveučilišta u Zagrebu
    Type of institution: University/Faculty
    Type of cooperation: Systematic exchange of information
    City: 10000 - Zagreb, Croatia

  2. Name of institution: Department of Mechanical Engineering, Michigan State University, East Lansing, MIchigan, USA
    Type of institution: University/Faculty
    Type of cooperation: Systematic exchange of information
    City: East Lansing, USA, Michigan

  3. Name of institution: Department of Mechanical, Industrial and Nuclear Engineering, University of Cincinnati, Cincinnati, Ohio, USA
    Type of institution: University/Faculty
    Type of cooperation: Systematic exchange of information
    City: CINCINNATI, Ohio, USA

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Last update: 09/26/95