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Papers by Piotr Furmańczyk

Materials

This paper presents the research results on the mechanical behavior of the low-carbon rolled stee... more This paper presents the research results on the mechanical behavior of the low-carbon rolled steel of a sea portal crane after a 33-year operation depending on the operational stresses and rolling direction in order to assess its serviceability. The tensile properties of steels were investigated using rectangular cross-section specimens with different thicknesses and the same width. Strength indicators were slightly dependent on the considered factors (operational conditions, the cutting direction, and thickness of specimens). However, a clear trend of higher ultimate strength for thinner specimens was noticed, especially in the case of more brittle material due to its operational degradation. Plasticity of the tested steel specimens was more sensitive to the influence of the above-mentioned factors than strength but less sensitive than impact toughness. Uniform elongation was slightly less for thinner specimens regardless of the investigated steel state or the orientation of specim...

Laser welding of similar girth joints is a commonly used method of permanent joining process. Par... more Laser welding of similar girth joints is a commonly used method of permanent joining process. Parameters can be easily analytically estimated. Nevertheless, performing more advanced types of joints, such as girth joints, is more complex. Estimating process parameters using numerical simulation can be performed. Assuming laser beam energy absorption in material heat expansion isotherms of a melting point can be calculated. Performing girth joint requires adequate angle process head orientation and welding parameters. Laser welding process is an unconventional method and does not require any additional material. The arc welding of a flange joint requires a multi run welding, and a single run welding can be performed using a laser beam. The article presents the possibility of numerical modeling laser welding of girth joints using the SimufactWelding software. Thermal and thermo-mechanical analysis were performed. The parameters estimated in the laser welding simulation are the followin...

Archives of Metallurgy and Materials, 2018

The article presents the results of tests carried out on S355JR steel of ferrite-pearlite and fer... more The article presents the results of tests carried out on S355JR steel of ferrite-pearlite and ferrite-bainite microstructures. The strength properties and fracture toughness were determined. The critical value of fracture toughness was determined at the moment of crack initiation by measuring of the stretch zone width, and in the moment of reaching a subcritical crack growth of 0.2 mm. Determination of fracture toughness characteristics was carried out in accordance with the procedures of ISO and ASTM standards.

INŻYNIERIA MATERIAŁOWA, 2018

The crack tip opening displacement (CTOD), just like J integral, is a parameter characterising th... more The crack tip opening displacement (CTOD), just like J integral, is a parameter characterising the fracture toughness of materials. The CTOD values are typically determined at subcritical crack initiation, δ Ti , or at 0.2 mm subcritical crack extension, δ TC. The procedure for measuring δ TC is described in detail in ASTM 1820. Measuring δ Ti is far more complicated and requires specialised apparatus and trained operators. The aim of this study was to assess the capability of different methods used for determining the value of δ Ti. The results from the experiments were compared with those from numerical calculations, obtaining good agreement between δ Ti data determined by the methods applied. The CTOD was measured on SENB (single-edge-notch-bend) specimens made of S355JR steel subjected to laboratory based heat treatment. The tests were performed at temperature in the range-80°C to 20°C, which allowed assessing the impact of reduced temperature on the δ Ti level.

Biuletyn Instytutu Spawalnictwa, 2019

The article presents the possibilities of the numerical modelling of laser welding processes. In ... more The article presents the possibilities of the numerical modelling of laser welding processes. In laser welding, the concentrated beam of photons generates high surface power density and leads to the melting and even evaporation of some metal. The metal vapours ionize and form a keyhole. Because of its high linear power density, laser welding process makes it possible to form deep and narrow welds. However, this welding method requires the preparation of workpiece edges. It is possible to "bypass" this requirement by defocusing the laser beam. However, the foregoing entails a significant decrease in power density. An alternative involves the use of optical systems enabling the division of the beam. In CO2 gas lasers, the bisection of the laser beam is performed using a multi-faceted parabolic mirror. The modelling of welding processes can be carried out using both analytical and numerical methods. Analytical solutions provide approximate results and do not take into consideration many physical phenomena accompanying welding processes. In turn, numerical solutions provide a more accurate representation of welding processes, In addition, it is possible to modify the geometry of heat sources reflecting the keyhole effect of bifocal welding system. The paper presents results of the numerical simulation of the keyhole laser welding process in relation to a bifocal optical system. The results of the numerical simulation were verified experimentally by making test joints using parameters developed during numerical simulations. Both the shape of obtained welds and the hardness distribution identified in the cross-section of a joint made of low-alloy structural steel S235JR were subjected to tests in order to verify the numerical model.

Przegląd Spawalnictwa - Welding Technology Review, 2018

W artykule przedstawiono wyniki badań makro-i mikroskopowych oraz pomiary twardości doczołowych z... more W artykule przedstawiono wyniki badań makro-i mikroskopowych oraz pomiary twardości doczołowych złączy spawanych ze staliwa G17CrMo5-5. Ponadto została przeprowadzona analiza morfologii przełomów udarnościowych złączy spawanych. Złącza spawane wykonano metodą TIG.

Acta Mechanica et Automatica, 2018

In the paper are presented test results of fracture process in brittle-to-ductile transition rang... more In the paper are presented test results of fracture process in brittle-to-ductile transition range for two microstructural types of S355JR steel – ferrite-pearlite and ferrite-carbides. For both kinds of S355JR steel obtained in temperature range of transition region the strength and plastic properties are similar, but the fracture toughness characteristics showed significantly are various. To clarify the differences in the course of trends in the mechanical characteristics performed metallographic and fractographic observations using the scanning electronic microscope. The fractographic examination showed that changes in the fracture surface morphology were dependent on the test temperature. It was also found that during the subcritical crack growth the region of ductile fracture extension reduced with decreasing temperature. The results of finite element method (FEM) calculation the stress fields in front of the crack of single edge notch in bending (SENB) specimens in the range o...

Materials, 2021

Tensile uniaxial test is typically used to determine the strength and plasticity of a material. N... more Tensile uniaxial test is typically used to determine the strength and plasticity of a material. Nominal (engineering) stress-strain relationship is suitable for determining properties when elastic strain dominates (e.g., yield strength, Young’s modulus). For loading conditions where plastic deformation is significant (in front of a crack tip or in a neck), the use of true stress and strain values and the relationship between them are required. Under these conditions, the dependence between the true values of stresses and strains should be treated as a characteristic—a constitutive relationship of the material. This article presents several methodologies to develop a constitutive relationship for S355 steel from tensile test data. The constitutive relationship developed was incorporated into a finite element analysis of the tension test and verified with the measured tensile test data. The method of the constitutive relationship defining takes into account the impact of high plastic ...

$Research paper thumbnail of Analysis of the morphology of impact fractures of welded joints made of cast steel for the power industry of the Cr-Mo type with the addition of rare earth metals$

The article presents the results of tests of butt welded joints, ie. hardness distribution, macro... more The article presents the results of tests of butt welded joints, ie. hardness distribution, macro and microstructure. Analysis of surface morphology of impact fractures of G17CrMo5-5 welded joints was carried out. The welding process was carried out on two types of melts, ie. without modification and with addition of rare earth metals (REM) to liquid metal. Welded joints were made using the TIG method.

There are represented the results of the laboratory studies concerning the effect of the running ... more There are represented the results of the laboratory studies concerning the effect of the running coatings made of soft anti-friction metals applied by the process of electroerosive alloying on the surfaces of rings made of Р6М5 and 12X18H10T steels and having titanium nitride coatings applied by the method of condensed ion bombardment. It has been found that the running coatings reduce the values of frictional forces and frictional coefficients for all series of the specimens.