Wyniki wyszukiwania - BazTech

1

The Analysis of Filler Material Effect on Properties of Excavator Crawler Track Shoe after Welding Regeneration

Gucwa M., Winczek J., Wieczorek P., Mičian M., Koňár R.

Archives of Metallurgy and Materials

|

2021

|

Vol. 66, iss. 1

31--36

EN

The application of hardfacing is one of the ways to restore the functional properties of worn elements. The possibility of using filler materials rich in chrome allows for better wear resistance than base materials used so far. The paper presents the results of research on the use of 3 different grades of covered electrodes for the regeneration of worn track staves. The content of the carbon in the covered electrodes was from 0,5% to 7% and the chromium from 5% to 33%. The microscopic and hardness tests revealed large differences in the structure and properties of the welds. The differences in the hardness of the welds between the materials used were up to 150 HV units. The difference in wear resistance, in the ASTM G65 test, between the best and worst materials was almost 12 times big.

2

Physical Simulation of Individual Heat-Affected Zones in S960MC Steel

Mičian M., Winczek J., Harmaniak R., Koňár R., Gucwa M., Moravec J.

Archives of Metallurgy and Materials

|

2021

|

Vol. 66, iss. 1

81--89

EN

This research is focused on the analysis of heat-affected sub-zones in 2 mm thick steel S960MC samples, with the aim of observing and evaluating the mechanical properties after exposure to temperatures corresponding to individual heat-affected sub-zones. Test samples were prepared using a Gleeble 3500 thermo-mechanical simulator. The samples were heated in the range from 550°C to 1350°C and were subsequently quickly cooled. The specimens, together with the base material, were then subjected to tensile testing, impact testing, and micro-hardness measurements in the sample cross-section, as well as evaluation of their microstructure. Fracture surfaces are investigated in samples after impact testing. The heat-affected sub-zones studied indicate high sensitivity to the thermal input of welding. There is a significant decrease in tensile strength and yield strength at temperatures around 550°C.

3

The Evaluation of the Wear Mechanism of High-Carbon Hardfacing Layers

Winczek J., Gucwa M., Mičian M., Koňár R., Parzych S.

Archives of Metallurgy and Materials

|

2019

|

Vol. 64, iss. 3

1111--1115

EN

Materials based on cast irons are often used for protection against wear. One of the methods of creating protective surface with cast iron structures is hardfacing. The application of hardfacing with self shielded flux cored wire with high carbon content is one of the economical ways often used to protect machinery parts exposed to both abrasion and erosion. The wear resistance of hardfacings depends on their chemical composition, structure obtained after hardfacing, parameters of depositing process andspecific conditions of wear. As the base material in the investigation the steel grade S235JR was used. The wear behavior mechanism of hardfacings made with one type of self shielded flux cored wire and different process parameters were evaluated in thispaper. Structures obtained in deposition process were different in hardness, amount of carbides and resistance to wear with two investigated impingement angles. The erosion tests showed that impingement angle 30° gives lower erosion rate than angle 60°.

4

Ultrasonic Control of Ductile Cast Iron Castings by Phased Array Technique

Boháčik M., Mičian M., Koňár R., Trško L., Winczek J.

Archives of Foundry Engineering

|

2019

|

iss. 2

9--14

EN

The goal of this article is non-destructive ultrasonic testing of internal castings defects. Our task was to cast several samples with defects like porosity and cavities (where belongs mostly shrinkages) and then pass these samples under ultrasonic testing. The characteristics of ultrasonic control of castings are presented in the theoretical part of this article. Ultrasonic control is a volume non-destructive method that can detect internal defects in controlled materials without damaging the construction. It is one of the most widely used methods of volume non-destructive testing. For experimental control were made several cylindrical samples from ferritic grey and ductile cast iron. Because of the form and dispersion of graphite of grey cast iron it was not possible to make ultrasonic records on this casting with probe we used, so we worked only with ductile cast iron. Ultrasonic records of casting control are shown and described in the experimental part. The evaluation of the measurement results and the reliability of the ultrasonic method in castings control is listed at the end of this article.

5

The modelling of temperature-dependent stress-strain curves for weldable steels

Winczek J., Mičian M., Ivanov V.

Journal of Applied Mathematics and Computational Mechanics

|

2018

|

Vol. 17, nr 3

111--117

EN

The calculation of stresses in the steel elements subjected to the thermomechanical loads requires taking into account the influence of temperature on mechanical properties of a material, including the stress-strain curve. The simplified and extended computational models of temperature-dependent tensile curves have been discussed. The methodology of the stress-strain curve construction in the entire temperature range of the solid state of the material has been proposed. The considerations are illustrated by the examples of calculated stress-strain curves in different temperatures for S235 and S355 welding steels.

6

Analysis of thermal cycles and phase transformations during multi-pass ARC weld surfacing of steel casts taking into account heat of the weld

Winczek J., Gucwa M., Makles K.

Journal of Applied Mathematics and Computational Mechanics

|

2018

|

Vol. 17, nr 1

89--100

EN

In this work, a model of phase transformations during multipass weld surfaced steel casts is presented. In the temperature field calculation algorithm, the influence of the heat of overlaying beads and a self-cooling of previously overlayed beads have been taken into account. The fusion area, full and part transformation zones, by solidus, A1 and A3 and A A1 temperatures has been determined, respectively. The temperatures of the beginning and the end of the phase changes during cooling were determined on the basis of the time-temperature-transformation welding diagram. In the phase change kinetic description, the JMAK law and KM formula were used. Theoretical considerations are illustrated by example of volume share calculations of particular structural components during the weld surfaced 230-450 W steel cast. The results of computation in the graphical forms are presented: welding thermal cycle diagrams and structural share change histories at selected points, as well as temperature and the phase share distributions in cross section.

7

The Analysis of Thermomechanical States in Multipass Arc Weld Surfaced Steel Elements

Winczek J.

Archives of Metallurgy and Materials

|

2018

|

Vol. 63, iss. 4

1615--1628

EN

The paper presents the analysis of temperature fields, phase transformations, strains and stresses in a cuboidal element made from S235 steel, surfaced with multipass GMA (Gas Metal Arc) method. The temperature field is described assuming a dual-distribution heat source model and summing up the temperature fields induced by the padded weld and by the electric arc. Dependence of stresses on strains is assumed on the basis of tensile curves of particular structures, taking into account the influence of temperature. The calculations were carried out on the example of five welds in the middle of the plate made of S235 steel. The simulation results are illustrated in graphs of thermal cycles, volume shares of structural components and stresses at the selected points of cross-section, and the temperature and strain distributions in the whole cross section.

8

The Repair of Foundry Defects in Steel Castings Using Welding Technology

Mičian M., Koňár R., Hlavatý I., Winczek J., Gucwa M.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 2

177--180

EN

Use of welding technology for the repair of steel castings is particularly common in two areas. These include weld surfacing of protrusions that remained incomplete after casting, or filling the surface defects (cavities). These defects are more common for steel casting than for graphite cast iron, due to the lower fluidity of steel. This article describes a suitable technological process of repairing the defects on the casting using the welding technology. A specimen produced for this purpose was prepared by carving a groove into a cast steel plate 20 GL, which was then filled with a weld metal using MAG (135) technology. The following evaluation of the basic characteristics of the repaired site point to the suitability of the selected technological parameters of the repair procedure. Metallographic evaluation was carried out, further evaluation of mechanical properties by tensile test, bend test and Vickers hardness test. The proposed methodology for the evaluation repair of foundry defects in steel castings also meets the requirements for the approval of welding procedures in accordance with the relevant valid legislation.

9

Analysis of heat release in compression ignition engine

Tutak W., Gnatowska R., Winczek J., Gawrońska E.

Prace Naukowe Akademii im. Jana Długosza w Częstochowie. Technika, Informatyka, Inżynieria Bezpieczeństwa

|

2017

|

T. 5

67--74

EN

The main goal of this research was to analyze the heat release in a compression ignition (CI) engine. Work contains description of the combustion process in the combustion chamber of CI engine with an explanation of the combustion stages. The research was conducted for wide range of load. At full load of engine achieved the highest value of pressure rise, temperature, fuel consumption and indicated mean effective pressure. The lowest values of these parameters were obtained for the smallest load. The full load of engine was characterized by the highest value of the heat release, and the longest combustion period due to the large share of diffusion combustion phase. The lowest load was characterized by 3.5 times less in value of heat release than in case of maximum load and heat release rate course was without visible diffusion combustion phase.

PL

Głównym celem badań było przeprowadzenie analizy wydzielania ciepła w silniku o zapłonie samoczynnym. Badana jednostka to sześciocylindrowy silnik z zapłonem samoczynnym o mocy 80 kW, poddany obciążeniom w szerokim zakresie. Dla obciążenia maksymalnego uzyskano największy przyrost ciśnienia, temperatury, godzinowego zużycia paliwa oraz ciśnienia indykowanego. Najmniejsze wartości powyższych parametrów zostały uzyskane dla najmniejszego obciążenia. Obciążenie maksymalne charakteryzuje się najwyższą ilością wydzielonego ciepła, a także najdłuższym procesem spalania za sprawą dużego udziału spalania dyfuzyjnego. Przy obciążeniu minimalnym wydzielania ciepła było 3,5- krotnie mniej niż dla maksymalnego, ponadto proces spalania trwał najkrócej, bez widocznego udziału spalania dyfuzyjnego.

10

The Effect of Type of Welding Sequence During Hardfacing Chromium Cast Iron for Erosion Resistance

Gucwa M., Bęczkowski R., Winczek J., Wyleciał T.

Archives of Foundry Engineering

|

2017

|

Vol. 17, iss. 3

51--54

EN

The paper presents the capabilities of welding techniques to creating properties of wear resistant high chromium cast iron alloy. The use of the right kind of welding sequence allows you to change the structure and properties of the obtained welds. Tests were conducted for one type of additive material in the form of self shielded core wire. In order to determine the effect of the type of welding sequence on the properties of welds performed welding using string bead and weave bead. The resulting weld was tested on hardness and research structure in an optical microscope. In the following studies have been made erosive tests wear of made hardfacing. String beads gave structure rich in carbides and harder about 270 HV of the weld with weave bead. Also, wear resistance was nearly twice as better for welds made with string beads. In the experiment a decisive role in the resistance to wear plays a high hardness of the deposit and the presence of carbides in its structure. Changes in the basic parameters of the deposition process allows for the formation of structure and properties of hardfacing welds in a wide range.

11

Modeling of thermal cycle ci engine with multi-stage fuel injection

Jamrozik A., Tutak W., Gnatowski A., Gnatowska R., Winczek J., Sosnowski M.

Advances in Science and Technology. Research Journal

|

2017

|

Vol. 11, no 3

179--186

EN

This work presents a complete thermal cycle modeling of a four-stroke diesel engine with a three-dimensional simulation program CFD - AVL Fire. The object of the simulation was the S320 Andoria engine. The purpose of the study was to determine the effect of fuel dose distribution on selected parameters of the combustion process. As a result of the modeling, time spatial pressure distributions, rate of pressure increase, heat release rate and NO and soot emission were obtained for 3 injection strategies: no division, one pilot dose and one main dose and two pilot doses and one main dose. It has been found that the use of pilot doses on the one hand reduces engine hardness and lowers NO emissions and on the other hand, increases soot emissions.

12

The influence of the heat source model selection on mapping of heat affected zones during surfacing by welding

Winczek J.

Journal of Applied Mathematics and Computational Mechanics

|

2016

|

Vol. 15, nr 3

167--178

EN

The paper compares forms and dimensions of heat affected zones determined on the basis of analytical descriptions of temperature fields caused by different models of heat source. In the first case, a single-distributed volumetric heat source model reflecting only the impact of an electric arc was assumed. In further considerations, bimodal heat source models were applied. The first one consists of a volumetric heat source model of weld reinforcement (of melted electrode material) and a surface model of an electric arc. In the second one a bimodal source is the sum of volumetric heat source models of weld reinforcement and an electric arc. Calculations are based on the example of submerged arc welding of a rectangular S355 steel element. The results of numerical simulations were verified experimentally, confirming the argument that it is necessary to include the bimodal heat source in temperature field modelling, which takes into account the temperature rises caused by the heat of melted electrode material.

13

Thermomechanical States in Arc Weld Surfaced Steel Elements

Winczek J., Skrzypczak T.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 3

1623--1634

EN

Kinetics of phase transformations during heating is limited by temperature values at the beginning and at the end of austenitic transformation, while the progress of phase transformations during cooling is determined on the basis of TTT-welding diagram and Johnson-Mehl-Avrami and Kolomogorov law for diffusive transformations and Koistinen-Marburger for martensitic transformation. Stress state of a bar subjected to thermo-mechanical loads is described assuming the plane cross section hypothesis and using integral equations of stress equilibrium of a bar as well as simple Hook’s law. Stresses in the elastic-plastic state are determined by iteration using solutions with a variable elastic modulus of elasticity, conditioned by tensile curves. Dependence of stresses on strains is assumed on the basis of tensile curves of particular structures, taking into account the influence of temperature. There were performed calculations of the temperature field, phase transformations, strains and stresses for GMAW surfacing of a cuboid element made of S235 steel. Authors’ programs, made in Borland Delphi, were used for calculations.

14

Structure and Properties of Coatings Made with Self Shielded Cored Wire

Gucwa M., Winczek J., Bęczkowski R., Dośpiał M.

Archives of Foundry Engineering

|

2016

|

Vol. 16, iss. 3

39--42

EN

The welding technologies are widely used for design of protection layer against wear and corrosion. Hardfacing, which is destined for obtaining coatings with high hardness, takes special place in these technologies. One of the most effective way of hardfacing is using self shielded flux cored arc welding (FCAW-S). Chemical composition obtained in flux cored wire is much more rich in comparison to this obtained in solid wire. The filling in flux cored wires can be enriched for example with the mixture of hard particles or phases with specified ratio, which is not possible for solid wires. This is the reason why flux cored wires give various possibilities of application of this kind of filler material for improving surface in mining industry, processing of minerals, energetic etc. In the present paper the high chromium and niobium flux cored wire was used for hardfacing process with similar heat input. The work presents studies of microstructures of obtained coatings and hardness and geometric properties of them. The structural studies were made with using optical microscopy and X- ray diffraction that allowed for identification of carbides and other phases obtained in the structures of deposited materials. Investigated samples exhibit differences in coating structures made with the same heat input 4,08 kJ/mm. There are differences in size, shape and distribution of primary and eutectic carbides in structure. These differences cause significant changes in hardness of investigated coatings.

15

The model of temporary temperature field during multi-pass arc weld surfacing. Pt. 1, Analitycal description

Winczek J., Rygał G., Skrzypczak T.

Journal of Applied Mathematics and Computational Mechanics

|

2015

|

Vol. 14, nr 2

123--130

EN

This work presents a model of a temperature field in a steel element during multi-pass Gas Metal Arc Weld surfacing taking into account heat of the melted electrode material. An analytical solution for a half-infinite body model is obtained by aggregating temperature increments caused by applying liquid metal and heat radiation of a moving electrode. The assumptions are Gaussian distributed heat sources of applied melted electrode material and of an electric arc.

16

The model of a temporary temperature field during multi-pass arc weld surfacing. Pt. 2, Example of computations

Winczek J., Rygał G., Skrzypczak T.

Journal of Applied Mathematics and Computational Mechanics

|

2015

|

Vol. 14, nr 3

141--148

EN

In this work computations of a temperature field are carried out during multipass Gas Metal Arc Weld surfacing of a cuboidal steel element taking into account heat of the melted electrode material. The results are presented in the form of temporary and maximum temperature distribution in the element’s cross-section and thermal cycles at selected points.

17

Modelling of a temporary temperature field during arc weld surfacing of steel elements taking into account heat of the weld

Winczek J., Rygał G.

Journal of Applied Mathematics and Computational Mechanics

|

2015

|

Vol. 14, nr 1

111-120

EN

In this work, a model of a temperature field in a steel element during a singlepass arc weld surfacing is presented. Analytical solution for half-infinite body model is obtained by aggregating temperature increments caused by applying liquid metal and heat radiation of a moving electrode. The assumptions are Gaussian distributed heat sources of applied metal and the weld and of an electric arc heat source. Computations of the temperature field were carried out during arc weld surfacing of cuboidal steel element. The results are presented as temporary and maximum temperature distribution in the element’s crosssection and thermal cycles at selected points. The accuracy of the solution is verified comparing a calculated fusion line to that obtained experimentally.

18

Effect Of Natural Convection On Directional Solidification Of Pure Metal

Skrzypczak T., Węgrzyn-Skrzypczak E., Winczek J.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2A

835--841

EN

The paper is focused on the modeling of the directional solidification process of pure metal. During the process the solidification front is sharp in the shape of the surface separating liquid from solid in three dimensional space or a curve in 2D. The position and shape of the solid-liquid interface change according to time. The local velocity of the interface depends on the values of heat fluxes on the solid and liquid sides. Sharp interface solidification belongs to the phase transition problems which occur due to temperature changes, pressure, etc. Transition from one state to another is discontinuous from the mathematical point of view. Such process can be identified during water freezing, evaporation, melting and solidification of metals and alloys, etc. The influence of natural convection on the temperature distribution and the solid-liquid interface motion during solidification of pure copper is studied. The mathematical model of the process is based on the differential equations of heat transfer with convection, Navier-Stokes equation and the motion of the interface. This system of equations is supplemented by the appropriate initial and boundary conditions. In addition the continuity conditions at the solidification interface must be properly formulated. The solution involves the determination of the temporary temperature and velocity fields and the position of the interface. Typically, it is impossible to obtain the exact solution of such problem. The numerical model of solidification of pure copper in a closed cavity is presented, the influence of the natural convection on the phase change is investigated. Mathematical formulation of the problem is based on the Stefan problem with moving internal boundaries. The equations are spatially discretized with the use of fixed grid by means of the Finite Element Method (FEM). Front advancing technique uses the Level Set Method (LSM). Chorin’s projection method is used to solve Navier-Stokes equation. Such approach makes possible to uncouple velocities and pressure. The Petrov-Galerkin formulation is employed to stabilize numerical solutions of the equations. The results of numerical simulations in the 2D region are discussed and compared to the results obtained from the simulation where movement of the liquid phase was neglected.

PL

Praca porusza problematykę modelowania kierunkowego krzepnięcia czystego metalu. Podczas tego procesu obserwuje się formowanie ostrego frontu krzepnięcia w postaci powierzchni separującej ciecz i ciało stałe w przypadku trójwymiarowym lub krzywej w przypadku płaskim. Położenie oraz kształt interfejsu krzepnięcia zmieniają się w czasie a wartości prędkości lokalnych zależą od różnicy intensywności strumieni ciepła po stronie ciała stałego i cieczy. Krzepnięcie z ostrym frontem należy do grupy procesów z przemianami fazowymi, które warunkowane są zmianami temperatury, ciśnienia, itp. Przejście fazowe z jednego stanu w drugi ma z matematycznego punktu widzenia charakter nieciągły. Procesy tego typu można zidentyfikować podczas zamarzania wody, parowania, topnienia i krzepnięcia metali i stopów, itp. W pracy zbadano wpływ zjawiska konwekcji swobodnej na chwilowy rozkład temperatury oraz ruch granicy narastania fazy stałej podczas krzepnięcia czystej miedzi w obszarze płaskim. Model matematyczny sformułowano na bazie równań różniczkowych transportu ciepła z konwekcją, Naviera-Stokesa i ruchu frontu krzepnięcia. Układ równań uzupełniono odpowiednimi warunkami początkowymi i brzegowymi oraz warunkami ciągłości na froncie. Rozwiązanie obejmuje chwilowe rozkłady temperatury, prędkości oraz położenie granicy międzyfazowej. Sformułowanie matematyczne zagadnienia bazuje na modelu z ruchomymi granicami wewnętrznymi, czyli tzw. modelu Stefana. Równania zostały zdyskretyzowane przestrzennie z wykorzystaniem metody elementów skończonych. W modelu numerycznym wykorzystano siatkę niezmienną w czasie. Do propagacji frontu użyto metody poziomic. Do wyznaczenia prędkości w cieczy wykorzystano metodę rzutowania, która poprzez eliminację ciśnienia z równania pędu pozwala na rozprzężenie prędkości i ciśnień. Równania rozwiązano z wykorzystaniem sformułowania Petrova-Galerkina. Omówiono wyniki analizy numerycznej oraz porównano je z wynikami otrzymanymi z symulacji, w której pominięto ruch cieczy.

19

The Properties of High Chromium Hardfacings Made with Using Pulsed Arc

Gucwa M., Winczek J.

Archives of Foundry Engineering

|

2015

|

Vol. 15, iss. 1 spec.

37--40

EN

The paper discusses the possibility of using pulsed arc hardfacing for depositing high chromium and carbon surfaces. In these studies self-shielded cored wire was used as a material for hardfacing. Pulsed arc is used in welding technologies to better control of transport molten metal in the welding arc and heat input. The correct heat input results in limited dilution surfaces that is very important in wear prevention technologies. The paper presents the results of research on the geometric parameters and hardness of deposited surfaces. The investigation was carried out with various welding parameters that were designed in heat source. The survey was conducted on the specimens that were subjected to metallographic examination hardness test.

20

Modelowanie strefy wpływu ciepła podczas jednościegowego napawania z wykorzystaniem dwurozkładowego modelu źródła ciepła

Winczek J.

Modelowanie Inżynierskie

|

2014

|

T. 19, nr 50

69--76

PL

Przyjmowane w opisach pola temperatury podczas napawania jednorozkładowe modele źródła nie pozwalają na odtworzenia nieregularnych kształtów izoterm (w tym linii wtopienia), dlatego też zaproponowano model dwurozkładowy, znajdując uzasadnienie w sposobie przekazywania do napawanego przedmiotu ciepła wydzielonego przez łuk elektryczny. Wykonano obliczenia pola temperatury dla przykładu jednościegowego napawania płyty ze stali S235. Uzyskano potwierdzenie wymiarów i kształtu linii wtopienia uzyskanej doświadczalnie przez innych badaczy, używając w obliczeniach parametrów napawania przyjętych w eksperymencie. Wartości maksymalnej temperatury umożliwiły wyznaczenie charakterystycznych stref wpływu ciepła. Obliczono udziały objętościowe poszczególnych składników strukturalnych (ferrytu, perlitu i bainitu).

EN

Single-distributed heat source models accepted in the descriptions of the temperature field during surfacing by welding, do not allow for restoration of irregular isotherms shapes (including the fusion line), therefore a bimodal model is proposed, finding justification in the way of transmitting heat generated by an electric arc to the surfaced object. Calculations of the temperature field were performed for a single-pass surfaced S235 steel plate. The size and shape of the fusion line, experimentally obtained by other investigators, was confirmed, using in the calculations the welding parameters adopted in the experiment. The maximum temperature allowed for the determination of specific heat affected zones. The volume fractions of particular structural components (ferrite, pearlite and bainite) were calculated.