Božidar Liščić

Božidar Liščić
University of Zagreb · Faculty for Mech.Engineering and Naval Architecture

Prof.Dr.sc.

About

55
Publications
25,712
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538
Citations
Citations since 2016
5 Research Items
186 Citations
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2016201720182019202020212022010203040
2016201720182019202020212022010203040

Publications

Publications (55)
Article
Full-text available
In the paper some unusual processes are considered during quenching such as self-regulated thermal process when metallic probe is covered by insulating polymeric layer, oscillation of temperature in surface layers of probe, creation a “shoulder” when quenching in polymer solution, possibility to perform austempering process just in cold liquids. Ab...
Article
Full-text available
In contrast with small laboratory probes developed to evaluate the cooling properties of relatively small samples of a quenchant, the new Liscic/Petrofer probe is designed to measure and record the quenching intensity under real industrial conditions. The Liscic/Petrofer probe is a cylindrical Inconel 600 probe with a 50-mm diameter and a 200-mm le...
Article
Full-text available
The technology of High Pressure Gas Quenching (HPGQ) in modern vacuum furnaces has already reached the level of 20 to 25 bar pressure and up to 80 m/s gas flow velocity. By using primarily nitrogen (N2) it is possible to quench also low-alloyed steels, and to compete, in some cases successfully, with oil quenching. This depends basically on the har...
Article
Full-text available
The cooling characteristics of a liquid quenchant are usually determined by a laboratory test using a small cylindrical probe with one thermocouple in its geometrical center. The reasons why the results of the laboratory tests do not represent the real quenching intensity of quenching workpieces in workshop conditions are described. Instead, a new...
Article
Full-text available
Quenching Research Centre (QRC) was established at the beginning of 2010 through the financial support for excellence of the Ministry of Science Education and Sport, of the Republic of Croatia. The main investigation and research possibilities and potentials of the QRC are: quenching in liquids or in a salt bath and cooling by high pressure gases....
Article
The signifi cant growth of renewable energy production in the past decades is present mainly due to the global depletion of fossil fuel reserves. One of interesting and well developed renewable energy technologies are wind turbines which are mainly built onshore. Due to more favorable wind characteristics at sea, off shore wind power plants are an...
Chapter
Full-text available
Heat transfer mechanisms at quenching in evaporable liquid quenchants, and at high pressure gas quenching in vacuum furnaces, are described. In three different Liscic probes, the temperature gradient method is used to evaluate the cooling intensity at quenching in laboratory and workshop environments. Calculation of the heat transfer coefficient is...
Article
Full-text available
The common test for assessing hardenability is the standardised Jominy end-quench test according to ASTM-A255 or DIN-EN 50191. This test is applied essentially for non-alloyed and low alloyed structural steels, when quenched in liquid quenchants, but it is not applicable for high alloyed (air hardening) steels, because the cooling rate at the oppos...
Article
Full-text available
Quenching steel parts by immersing them in liquid quenchants is still the most used method for hardening carbon and low alloyed structural and tool-steels. The achieved hardness, residual stresses and distortion of a workpiece depend on the selection of the quenchant, the phenomena of nonlinear heat transfer and on used cooling parameters. The non-...
Chapter
ASM Handbook, Volume 4A is the first in a series of five ASM Handbook volumes covering heat treating. This volume includes 50 articles that address the physical metallurgy of steel heat treatment and thoroughly cover the many steel heat treating processes. Fundamentals of hardness and the use of hardenability as a selection factor are discussed as...
Conference Paper
Full-text available
In the last three decades, simulation of the quenching process has become a widely accessible engineering tool. One of the most important inputs for computer models is adequate heat transfer data on the quenching process. Yet there is no generally recognized method and technique for measurement, recording and comparison of relative cooling intensit...
Article
Full-text available
Resume This paper explains the need for a database of cooling intensities for liquid quenchants, in order to predict the quench hardness, microstructure, stresses and distortion, when real engineering components of complex geometry are quenched. The existing laboratory procedures for cooling intensity evaluation, using small test specimens, and Lum...
Article
Full-text available
For computer simulation of a quenching process, the fundamental prerequisite is to have the relevant heat transfer coefficient (HTC) calculated as function of workpiece's surface temperature and time respectively. In order to calculate the HTC, experimental measurement of the temperature-time history (cooling curve) near the workpiece surface is ne...
Article
Full-text available
Originating from discussions held in Rio de Janeiro in July 2010, a proposal was made to IFHTSE that an international collaborative project should be launched with the objective of producing a comparative database of the cooling intensities of liquid quenchants for use industrially as a selection tool in relation to specific materials, conditions,...
Article
Full-text available
Hardenability is an inherent property of every steel, usually characterized by the Jominy end-quenched test. For steel grades quenched in liquid quenchants this test is enough selective, and for them a good fixed correlation between cooling time from 800 to 500 o C (t 8/5) and the distance from the quenched end can be established. For steel grades...
Article
Full-text available
For computer simulation of a quenching process, the fundamental prerequisite is to have the relevant heat transfer coefficient (HTC) calculated as a function of the workpiece’s surface temperature and time respectively. In order to calculate the HTC experimental measurement of the temperature–time history (cooling curve) near the workpiece surface...
Article
Full-text available
A quench probe, based on the Temperature Gradient method was used to measure and record cooling curves when quenching real axially symmetric workpieces of any complex shape in liquid quenchants. Calculation of relevant heat transfer coefficients is based on the cooling curve measured just below surface of the cylindrical probe of 50-mm diameter. A...
Article
Full-text available
A new Temperature Gradient System has been designed for practical use when quenching real workpieces in any kind of liquid quenchants. The main hardware component of the system is a cylindrical probe of 50 mm Dia. x 200 mm assembled with three thermocouples, and the temperature data acquisition unit for automatic drawing of cooling curves. The acco...
Article
Full-text available
The aim of this article is to discuss the measures to control the dynamic of heat extraction by changing some parameters during quenching. This is possible for workpieces of not too small a cross-section size, because transformation of the microstructure proceeds gradually from the surface to the core only when a particular point attains the temper...
Article
Full-text available
The aim of a joint project between the Stiftung Institut für Werkstofftechnik, Bremen (IWT), the company Ipsen International, and the Faculty of Mechanical Engineering and Naval Architecture (FMENA), the University of Zagreb is to develop a computer program for prediction of hardness on the axial section of axially-symmetrical workpieces of any com...
Article
Prof. Dr.-Ing. Božidar Liščić, geb. 1929, studierte Maschinenbau an der Technischen Fakultät der Universität in Zagreb, Kroatien. Nach dem Studium arbeitete er 10 Jahre in der damals größten Werkzeugmaschinenfabrik „Prvomajska“ (über 3000 Beschäftigte), die letzten drei Jahre als technischer Direktor. Von 1968 bis 1999 war er Dozent und Professor a...
Article
Full-text available
High pressure gas quenching became a modern way of quenching finally machined engineering components,having many advantages compared to quenching in liquid quenchants.The main shortcoming of this technology is the problem of achieving adequate hardness in the core of bigger workpieces,because of inadequate quenching intensity.Due to the possibility...
Article
Full-text available
First a review of the three mutually dependent parts of a quenching process i. e. the thermodynamic, the structure transformation, and the stress dependent process are shown. Further the problem with the heat transfer coefficient during quenching in liquid media is discussed. Methods for evaluation of the cooling intensity in the lab as well as in...
Chapter
Hardenability, in general, is defined as the ability of a ferrous material to acquire hardness after austenitization and quenching. This general definition comprises two subdefinitions: the ability to reach a certain hardness level (German: Aufhärtbarkeit) and the hardness distribution within a cross section (German: Einhärtbarkeit).
Article
Full-text available
High pressure gas quenching became a modern way of quenching finally machined engineering components, having many advantages compared to quenching in liquid quenchants. The main shortcoming of this technology is the problem of achieving adequate hardness in the core of bigger work-pieces, because of inadequate quenching intensity. Due to the possib...
Article
The International Federation for Heat Treatment and Surface Engineering (IFHTSE) discusses the importance of cross-border collaboration in heat treatment and surface engineering and the role of the federation. IFHTSE is a member of a European consortium developing a model scheme for education and training in surface engineering with pan-European re...
Article
As well as cooling curve analysis of quenchants in laboratory tests, the first and second critical heat-flux densities can be used to characterise quenching intensity in industrial practice. With the Liscic/Nanmac quench probe, it is possible to measure the second and then calculate the first of these parameters. Critical heat-flux densities have b...
Article
When modelling the fracture toughness of the investigated AISI M2 high-speed steel, the stress-modified critical strain criterion was used. The very important influence of microstructural parameters such as the volume fraction of undissolved eutectic carbides, their mean diameter, and the mean distance between the carbides, as well as the volume fr...
Conference Paper
Full-text available
The scope of this book is broadly within a domain of Heat treatment and surface Engineering, recent progress and emerging ideas in the fields of advanced heat treatment and surface engineering technology. Main topics are: advanced heat treating manufacturing processes, vacuum heat treatment, tempering process, documentation in heat treating process...
Article
The microstructure of AISI M2 high-speed steel can be substantially modified by a vacuum heat-treatment combined with a deep cryogenic treatment in order to optimize the ratio between hardness and fracture toughness. This ratio is significantly affected by the volume fractions of retained austenite and undissolved eutectic carbides, as well as by t...
Article
When modelling the fracture toughness of the investigated AISI M2 high-speed steel, the stress-modified critical strain criterion was used. The very important influence of microstructural parameters such as the volume fraction of undissolved eutectic carbides, their mean diameter, and the mean distance between the carbides, as well as the volume fr...
Article
Full-text available
Methods of measurement of quench severity, also known as quenching intensity or "cooling power", have been under development for many years. At the present time there are two methods that predominate. One test, which classifies quench oils according to cooling time, and has been used predominantly in the USA for approximately 40 years, is ASTM D 35...
Article
Full-text available
Polymer quenchants are being used increasingly in the heat treating industry. One reason for this increase is the continual engineering advancements that facilitate their replacement of quench oils and also water. In this paper, three technologies utilizing polymer quenchants will be reviewed. These include: inverse hardening, intensive quenching a...
Article
"Controllable delayed quenching" and the associated "inverse hardening" can be used to maximize depth of hardening, minimize residual stresses, and improve fatigue resistance of steel parts.
Article
Internationally recognized standards for gaging quenchant performance are available for nonagitated baths. Current work focuses on standards for agitated solutions, which more closely simulate real-world heat treating.
Article
For specified component properties, a computerised system enables instant precise selection of the optimum structural steel grade for hardening and tempering from many stored on a hardenability database. Unlike the established graphical method based on hardenability, it allows a flexible choice of quenching conditions. The program also calculates o...
Article
A computer-aided method is described for the selection of structural steels for hardening and tempering using hardenability data. The program is applicable to quenched and tempered round bars 20 to 90 mm in diameter. Correlation between positions in a bar with Jominy distances and the calculation of the optimum hardenability curve are obtained usin...
Article
Hardenability of steels can be quantified by the Jominy hardenability curves. The hardness trend alongside the Jominy specimen is basically determined by the chemical composition of the steel and its austenite grain size. In order to predict this trend many authors have established formulae to define hardness values at different distances of the qu...
Chapter
The rapid cooling of hardenable steels or age-hardenable aluminum alloys is usually achieved by their immersion in, or their spraying with, fluids. The consequent changes in the mechanical properties of the materials — designated as hardness values in the simplest case — are determined by the temperature/time profiles attained during quenching.
Chapter
Predictions of material strength are an important technological challenge but extremely complicated and complex. When defining the strength properties obtained through cooling processes, researchers today tend to confine themselves to the hardness value. Determining the hardness of a component is simple and thus economical, and hardness measurement...
Book
Heat treatment of metallic alloys constitutes an important step within the production process. The heat treatment process itself is considered as a cycle of heating the workpieces to a predetermined temperature, keeping them at this temperature for the time period required, and cooling them to room temperature in an appropriate way. The process of...
Article
Full-text available
A new computer-aided method is described for measuring and recording quenching intensity under workshop conditions using a special cylindrical probe. The method is based on measuring the temperature gradient at the probe surface and representing the quenching intensity as heat flux density. The method is applicable for different quenchants, quenchi...
Article
Full-text available
The authors have developed a computerized technique for establishing hardening and tempering parameters for engineering steels with the aims of optimizing the treatment and ensuring control over the properties imparted. In this article, they outline the approach, with emphasis on the necessary software to cater for the austenitization, quenching an...
Article
In the paper a comparison of mechanical properties is drawn between standard qualities of ductile iron without heat treatment, quenched and tempered ductile iron as well as austempered ductile iron. The austempering process of ductile iron, resulting in the structure of bainitic ferrite and retained austenite, is described. The process parameters a...
Article
The paper describes the results of experiments with the surface transformation hardening by means of a laser beam on specimens made of nonalloyed steels C. 1120 and C. 1530 and gray iron SL-26 by use of the continuous CO//2 laser of 5 kw power output. The principle of the mentioned laser functioning, as well as the interaction between the laser bea...

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Project (1)
Archived project
This paper co-authored with Nikolai Kobasko from IQ Technologies, Inc. Akron, USA, will soon be published by Springer. Prof. Liscic