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No. 1/2020
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Contents


Bogdan GARBARZ
Dariusz WOŹNIAK
Mariusz ADAMCZYK
Władysław ZALECKI

Łukasiewicz Research Network – Institute of Ferrous Metallurgy

Janusz SIEMIENIEC
Aleksandra KRAWCZYK
Anna GWÓŹDŹ-KOTNIS

Huta Bankowa Sp. z o.o.

TECHNOLOGY OF HEAT TREATMENT OF THE LARGE SECTION BARS MADE OF STRUCTURAL STEEL USING CONTROLLED CONTINUOUS COOLING FROM THE AUSTENITE PHASE

The article presents the results of studies on the impact of accelerated cooling after the austenitisation of bars with a diameter of 180 mm made of structural steel S355J2 on the microstructure and mechanical properties. The aim of the research was to develop basic parameters of heat treatment technology using the heat remaining in the bars after hot rolling. Tests of heating and cooling of the bars were carried out in devices included in the line for semi-industrial hot rolling simulation, controlled cooling and heat treatment (LPS-B) at Łukasiewicz – IMŻ. The following cooling operations were performed after bar austenitisation: cooling in still air, controlled cooling with air blow, water-air mixture, water spraying and immersion cooling in water. Based on the research and analyses, it was found that the use of optimised variants of accelerated cooling leads to the modification of the microstructure and to grain refinement, without the formation of undesirable phase components. Consequently, the mechanical properties (yield strength and impact toughness) increase above the level obtained as a result of cooling in still air, including standard normalisation. Preliminary tests of accelerated air stream cooling of bars were carried out after austenitising in industrial conditions. The final criterion for selecting and implementing the type of technology for heat treatment of bars using heat after hot rolling in Huta Bankowa’s technical and technological conditions will be the assessment of the economic efficiency of the project.

Keywords: structural steel, phase transformations, microstructure, mechanical properties, accelerated cooling


Jarosław MARCISZ
Bogdan GARBARZ
Jerzy STĘPIEŃ

Tymoteusz TOMCZAK

Łukasiewicz Research Network – Institute of Ferrous Metallurgy

Lech STARCZEWSKI
Robert NYC
Michał GMITRZUK

Wojskowy Instytut Techniki Pancernej i Samochodowej

Marcin GOŁUŃSKI

Zakłady Mechaniczne Tarnów S.A.

PROTECTIVE EFFECTIVENESS OF ARMOUR MADE OF NANOBAINITIC STEEL

The article presents the results of tests on resistance to perforation of nanobainitic steel plates with a thickness in the range of 6–9 mm with the use of projectiles with different perforation mechanisms. Firing tests were carried out using 7.62×39 mm BZ ammunition in accordance with the requirements of the NATO Stanag 4569A standard document (level 2) and 7.62×54R mm B32 ammunition to determine the V50 parameter for selected variants and plate thickness. The plates constituting the testing material were manufactured on an industrial scale from two heats with different chemical composition. The nanobainitic steel plates were subjected to heat treatment including austenitisation, controlled cooling and direct isothermal annealing, the parameters of which were optimised in order to achieve the highest protective capacity. Microstructure studies were carried out in places where the projectile and the plate interacted, in order to analyse the effects of firing in detail. The obtained test results indicated limit values of projectile velocities and plate thicknesses for which ballistic protection is effective. The range of mechanical properties determined in a static tensile test as well as the type of microstructure were determined, including the content and form of retained austenite, guaranteeing compliance with the required level of resistance to perforation. Based on the results of the firing tests, heat treatment variants were selected for plates of a certain thickness intended for the armour of an observation and protective container. The studies and tests were carried out as part of the POIR 04.01.04-00-0047/16 project, the main goal of which is to reduce the weight of a LOOK container armour.

Keywords: nanobainitic steel, microstructure, mechanical properties, ballistic resistance


Wacław WITTCHEN
Mariusz BORECKI
Artur MAZUR

Łukasiewicz Research Network – Institute for Ferrous Metallurgy

USE OF THERMAL IMAGING TESTS IN THE STEEL INDUSTRY

The paper presents the possibilities and selected examples of practical use of the thermal imaging technique in the metallurgical industry as a non-invasive testing method for measuring temperature distribution on the surface of the examined object. This method can be used in all stages of steel production, from charge preparation to finished product, as well as diagnostics of technical devices. The paper emphasises the non-invasive nature of the examination, which does not disturb the production cycle.

Keywords: thermal imaging, thermography, infra-red, non-destructive testing, simulation processes


Sylwester ŻAK

ArcelorMittal Poland S.A.

Dariusz WOŹNIAK
Valeriy PIDVYSOTS’KYY

Łukasiewicz Research Network – Institute for Ferrous Metallurgy

Tomasz URBANIK

ArcelorMittal Poland S.A.

THE INFLUENCE OF THE SHAPE OF WORKING SURFACE OF STRAIGHTENING ROLLERS OF VERTICAL AND HORIZONTAL STRAIGHTENING MACHINES ON THE STATE OF RESIDUAL STRESSES IN RAILWAY RAIL – SECOND STAGE OF RESEARCHES

The paper presents the results of the second stage of work on the influence of the shape of straightening rollers on the state of residual stresses in rails, conducted as part of a project co-financed by the National Centre for Research and Development. The tests included numerical simulations of the rail straightening process using a new roll pass design of vertical and horizontal straightener rollers, determination of stress distribution maps in the rail after straightening in successive rollers of both straightening machines, as well as measurement of residual stresses in the rails after straightening operation in industrial conditions. The tests were carried out on R260 grade 60E1 rails. The reduction of tensile residual stresses in the centre of symmetry axis of the rail foot was obtained up to an average level of 32 MPa, i.e. by more than four times less in relation to the level achieved using traditional technology.

Keywords: railway rail, residual stresses, straightening process, straightening rollers


RESEARCH PROJECTS FUNDED FROM THE INSTITUTE’S OWN FUNDS – ABSTRACTS

2020-04-21


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