Influence of heating rate on sorbitic transformation temperature of tempering C45 steel

In this paper the analysis of speed heating influence on sorbitic transormation temperature of tempering C45 steel is presented. On thebasis of dilatometric research, functions associating heating time with initial and final temperature of sorbitic transformation have beendetermined as well as the size structural (γ) and thermal (α) expansion coefficients of quenching and tempering structures have beenestimated

The modeling of heat affected zone (HAZ) in submerged arc welding (SAW) surfacing steel element

In the work the bimodal heat source model in the description of the temperature field is presented. The electric arc was treated physically as one heat source, whose heat was divided: part of the heat is transferred by the direct impact of the electric arc, but another part of the heat is transferred to the weld by the melted material of the electrode. Computations of the temperature field during SAW surfacing of S355 steel element are carried out. The macrographic and metallographic analysis of the weld confirmed the depth and shapes of the fusion line and HAZ defined by the numerical simulation

Dilatrometrijska i analiza tvrdoće čelika C45 popuštanog uz različite brzine zagrijavanja

Modelling of technological processes of heat treatment or welding, involving multiple heat source transitions, requires considering the phenomenon of tempering. In work have been presented results of dilatometric research of hardened C45 steel subjected to tempering. The analysis of the influence of heating rate at the kinetic determined from dilatometric curves has been made. There have also been estimated quantities of transformation expansions and thermal expansion coefficients of hardening and tempering structures (austenite, ferrite, pearlite, martensite and sorbite). The analysis of tempering time influence on the hardness of tempered steel has been made. Functions associating hardness with tempering time (rate of heating-up) in technological processes based on short-timed action of a heat source (eg. laser treatment) have been suggested.Modeliranje tehnološkog procesa toplinske obrade ili zagrijavanja, uključivo višedjelne izvore prijelaza topline, zahtijeva razmatranje fenomena toplinske obrade popuštanje. U radu su prezentirani rezultati popuštanja tvrdoće zakaljenog čelika C45. Analiza utjecaja brzine zagrijavanja na kinetiku procesa je determinirana dilatometrijskim krivuljama. Procijenjeni su kvantitativni transformacijski izrazi i koefi cijent toplinskog širenja kaljenih i propuštenih struktura (austenit, perlit, mertenzit, sorbit). Napravljena je analiza utjecaja trajanja popuštanja na tvrdoću popuštenog čelika. Preporučena je funkcija koja udružuje tvrdoću i trajanje propuštanja (brzina zagrijavanja) u tehnološkom procesu temeljena na kratkotrajnom djelovanju izvora topline (npr. tretman laserom)

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

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

The Analysis of Stress States in Steel Rods Surfaced by Welding

W pracy przedstawiono sposób obliczeń stanów sprężysto - plastycznych w prętach obciążonych cieplnie, z uwzględnie- niem przemian fazowych zachodzących podczas napawania. Kinetykę przemian fazowych podczas nagizewania i chłodzenia limitują wartości temperatur początku i końca austenityzacji. natomiast postęp przemian podczas chłodzenia jest określony w oparciu o spawalniczy wykres ciągłego chłodzenia stali (CTPc-S). bazując na prawach Johnsona-Mehla-Avramiego-Kołomogo- rova (JMAK) w odniesieniu do przemian dyfuzyjnych i Koistinena-Marburgera dla martenzytycznej. Stan naprężenia pręta poddanego działaniu obciążeń cieplno-mechanicznych opisano przyjmując hipotezę płaskich przekrojów oraz korzystając z całkowych równań równowagi pręta Zależności naprężeń od odkształceń przyjęto na podstawie krzywych rozciągania po- szczególnych struktur z uwzględnieniem wpływu temperatury. Wykonano obliczenia pola temperatury, przemian fazowych, odkształceń i naprężeń płaskownika wykonanego ze stali S235, obciążonego punktowym spawalniczym źródłem ciepła o róż- nej intensywności. Przeprowadzono analizę powstawania i rozwoju odkształceń plastycznych. W oelu weryfikacji poprawności modelu przeprowadzono badania doświadczalne płaskownika wykonanego ze stali S235 napawanego metodą GMA. o geometrii i parametrach napawania przyjętych w symulacjach numerycznych. Porównano naprężenia własne obliczone z uwzględnieniem przemian fazowych oraz dla modelu materiału jednorodnego z wynikami badań doświadczalnych

The Analysis of Stress States in Steel Rods Surfaced by Welding

W pracy przedstawiono sposób obliczeń stanów sprężysto - plastycznych w prętach obciążonych cieplnie, z uwzględnie- niem przemian fazowych zachodzących podczas napawania. Kinetykę przemian fazowych podczas nagizewania i chłodzenia limitują wartości temperatur początku i końca austenityzacji. natomiast postęp przemian podczas chłodzenia jest określony w oparciu o spawalniczy wykres ciągłego chłodzenia stali (CTPc-S). bazując na prawach Johnsona-Mehla-Avramiego-Kołomogo- rova (JMAK) w odniesieniu do przemian dyfuzyjnych i Koistinena-Marburgera dla martenzytycznej. Stan naprężenia pręta poddanego działaniu obciążeń cieplno-mechanicznych opisano przyjmując hipotezę płaskich przekrojów oraz korzystając z całkowych równań równowagi pręta Zależności naprężeń od odkształceń przyjęto na podstawie krzywych rozciągania po- szczególnych struktur z uwzględnieniem wpływu temperatury. Wykonano obliczenia pola temperatury, przemian fazowych, odkształceń i naprężeń płaskownika wykonanego ze stali S235, obciążonego punktowym spawalniczym źródłem ciepła o róż- nej intensywności. Przeprowadzono analizę powstawania i rozwoju odkształceń plastycznych. W oelu weryfikacji poprawności modelu przeprowadzono badania doświadczalne płaskownika wykonanego ze stali S235 napawanego metodą GMA. o geometrii i parametrach napawania przyjętych w symulacjach numerycznych. Porównano naprężenia własne obliczone z uwzględnieniem przemian fazowych oraz dla modelu materiału jednorodnego z wynikami badań doświadczalnych

Temperature Field in Surfaced Steel Casts with the Heat of the Weld Taken into Account

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

Thermomechanical States in Arc Weld Surfaced Steel Elements

The paper presents a model of temperature, phase transformation and stresses fields in a steel element during single-pass Gas Metal Arc Weld (GMAW) surfacing

The Properties of High Chromium Hardfacings Made with Using Pulsed Arc

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

Thermomechanical States in Arc Weld Surfaced Steel Elements

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