Bimetalni lim St3S+Cu

The paper presents a theoretical analysis of the asymmetrical process of rolling bimetal plates composed of the base St3S layer and a Cu cladding layer. Investigation carried out aimed at determining the curvature of bimetal band depending on the value of roll peripheral speed asymmetry factor av. Computer simulations were performed on three different layer thickness ratios, HS/HH. Numerical studies were based on computer simulations carried out using the Forge 2D software. For computations, this program uses the finite-element method. The asymmetry of the process resulted from a non-uniform distribution of rolling reduction into the bimetal band layers, which caused the band to bend at the rolling mill exit. To counteract this behaviour, an asymmetry of working roll peripheral speeds was introduced.Članak daje teorijsku analizu učinka odnosa debljine sloja bimetalnih limova sastavljenih od osnovnog sloja St3S i sloja presvučenog bakrom. Provedena istraživanja su imala za cilj odrediti zakrivljenost bimetalne trake ovisno o vrijednosti faktora asimetrije av periferne brzine. Izvedene su kompjuterske simulacije tri sloja s različitim omjerima HS/HH debljine. Numeričke studije su se zasnivale na kompjuterskim simulacijama provedenim pomoću softvera Forge 2D. Za izračune, ovaj se program služi metodom konačnih elemenata. Asimetrija procesa rezultira od nejednolikog rasporeda redukcije u slojeve bimetalne trake koje uzrokuju savijanje trake na izlazu iz valjačkog stana. Kao protuteža takvom ponašanju uvedena je asimetrija perifernih brzina radnog valjka

Predviđanje zakrivljenosti bimetalne limene ploče Al-Cu tijekom asimetričnog hladnog valjanja

In the paper, solving a problem of rolling Al-Cu plates by the numerical way is presented. In the development of new technologies in rolling of bimetallic plates there are many problems both with ensuring a uniform strain distribution and producing a straight plate as well. Such a solution within research of the numerical simulation was obtained at the Forge 2 program based on finite element method. The cold rolling process was carried out at the temperature of 20 °C for 10 %, 20 % and 25 % relative rolling reduction. The curvature of bimetallic plate was numerically controlled by changing the speed of one roll. In this article the numerical analysis of asymmetrical rolling processes of plate composed with two metal layers, Al and Cu, has been done. At the work an influence of rotary speed ratio and value deformation on change of curvature bimetallic plate is determined.U radu je predstavljen numerički način rješavanja valjanja Al-Cu limenih ploča. U razvoju novih tehnologija za valjanje bimetalnih ploča ima mnogo problema i u osiguravanju jednolikog rasporeda deformacije i u proizvodnji ravnih ploča. U okviru provedenih istraživanja programa Forge 2, baziranom na metodi konačnih elemenata, ostvarena je numerička simulacija. Proces hladnog valjanja proveden je na temperaturi od 20 °C s relativnom redukcijom valjanja od 10 %, 20 % i 25 %. Zakrivljenost bimetalne ploče kontrolirala se numeričkim mijenjanjem brzine valjaka. U ovom članku napravljena je numerička analiza procesa asimetričnog valjanja ploče sastavljene od dva metal nasloja: Al i Cu. Također je utvrđen utjecaj omjera brzine rotacije i vrijednosti deformacije na promjenu zakrivljenosti metalne ploče

Optimization of Heat Treatment in Aspect of Production's Costs Reducing and Improving of Casting Quality from Duplex Cast Steel

Abstract The paper determines possibilities of cost optimisation in the production of GX2CrNiMoCu25-6-3-3 type duplex cast steel castings through selection of appropriate solution heat treatment temperature, which value depends on the content of alloying elements. Metallographic analysis was carried out for as-cast and heat treated cast steel. Hardness and impact strength of the cast steel were determined, which were correlated with the volume fraction of phases determined by means of ImagePro computer image analyser. It has been shown that increased carbon content creates a need to use higher treatment temperatures, thereby increasing the production cost. With increasing carbon content the cast steel hardness after solution heat treatment increases, however, crack resistance decrease

Susceptibility testing for welding of AlMg alloys intended for extrusion

The objective of research was to determine the weldability, using Tungsten Inert Gas (TIG) of extruded sections made of hard-deformable 5xxx series aluminum alloys with differing magnesium content, i.e. AlMg3, AlMg4,5, AlMg5, AlMg7. Welded joints were obtained as a result of a welding process consisting of several steps. Only welds characterized by very good appearance and quality were selected for tests. As a result of conducted research, TIG welding parameters were determined for sections with a thickness of 8 mm. It was observed that alloys of differing Mg content are characterized by high weldability and do not exhibit a significant reduction of the yield point. Moreover, joints exhibit uniform hardness distribution in the welded joint and heat-affected zone. Tensile strength is reduced

Solidification structure of massive castings from duplex cast steel,

SUMMARY Problems related with duplex massive cast production are presented in this work. Macro and microstructure investigations of GX2CrNiMoCu25-6-3-3 cast steel after solidification were done. The influence of cooling rates and segregation on intermetallic phases formation, especially sigma phase, were shown. The segregation process and cooling rates during solidification have great influence on intermetallic phases formation. Sigma phase occurrence in the cast structure causes deterioration of technological and functional properties

Influence of carbides morphology on fracture toughness of cast steel G200CrMoNi4-3-3

We analyze the influence of small modification of chemical composition of G200CrMoNi4-3-3 cast steel on the morphology of carbides and on material crack resistance. Using the Termo-Calc software the volume fraction of carbide phase was determined and the results correlated with microstructure observations. Crack resistance of cast steel was determined using SENB specimens and finding critical values of stress intensity factor KQ. Metallographic and fractographic observations of fracture surfaces allowed identifying the mechanism of cracking.Исследуется влияние незначительной моди­фикации химического состава литой стали G200СгМоNi4-3-3 на морфологию карбидов и трещиностойкость материала. С исполь­зованием расчетной программы Termo-Calc были выполнены оценка объемной доли карбидной фазы и сравнительный анализ полученных результатов с данными микрструктурных исследований. Трещиностой­кость литой стали исследовалась на образ­цах с краевой трещиной, для которых определялись критические значения коэффициента интенсивности напряжений KQ. Металлографические и фрактографические исследования поверхностей разрушения по­зволили определить механизм трещинообразования

Influence of carbides morphology on fracture toughness of cast steel G200CrMoNi4-3-3

We analyze the influence of small modification of chemical composition of G200CrMoNi4-3-3 cast steel on the morphology of carbides and on material crack resistance. Using the Termo-Calc software the volume fraction of carbide phase was determined and the results correlated with microstructure observations. Crack resistance of cast steel was determined using SENB specimens and finding critical values of stress intensity factor KQ. Metallographic and fractographic observations of fracture surfaces allowed identifying the mechanism of cracking.Исследуется влияние незначительной моди­фикации химического состава литой стали G200СгМоNi4-3-3 на морфологию карбидов и трещиностойкость материала. С исполь­зованием расчетной программы Termo-Calc были выполнены оценка объемной доли карбидной фазы и сравнительный анализ полученных результатов с данными микрструктурных исследований. Трещиностой­кость литой стали исследовалась на образ­цах с краевой трещиной, для которых определялись критические значения коэффициента интенсивности напряжений KQ. Металлографические и фрактографические исследования поверхностей разрушения по­зволили определить механизм трещинообразования

Analitičko i numeričko utvrđivanje prostiranja temperature na traci hlađenoj zrakom

The paper analyzes the distribution of temperature of 60S2A steel strip cooled in air. Both analytical and numerical methods were applied in investigation. From among the known analytical methods of temperature distribution determination, Tselikov’s [1], and the Fourier’s [2] methods were used. The numerical examination of temperature distribution presented in the paper involved carrying out a computer simulation of strip air cooling. For this purpose, the Forge 2D software [3] was employed, which relies on the finite-element method in performing computations. Comparison of results obtained by analytical methods with numerical computation results and for the real technological process has also been made within the study.U radu se analizira prostiranje temperature u čeličnoj traci 60S2A hlađenoj zrakom. Tijekom istraživanja primjenjivala se i jedna i druga metoda. Između poznatih analitičkih metoda utvrđivanja prostiranja temperature koristile su se Tselikova [1] i Fourierova [2] metoda. Numeričko ispitivanje temperature koje je prikazano u radu uključuje i provođenje kompjuterske simulacije hlađenja trake zrakom. U tu je svrhu primijenjen Forgeov software 2D [3] koji se u računanju oslanja na metodu konačnih elemenata. Unutar studije je također provedena i usporedba rezultata dobivenih analitičkim metodama s numeričkim izračunima

Microstructural and fracture analysis of aged cast duplex steel

The effect of increased carbon content and heat treatment parameters on the microstructure and selected properties of ferritic-austenitic duplex cast steel is discussed. Test results show that the cast steel microstructure after the solution heat treatment changes substantially with increasing carbon content. Ageing after the solution heat treatment results in approx. 20% increase in hardness and a few-times decrease in impact strength. Fractographic examinations show thatfracture surfaces of specimens of steel with low carbon content are typically of transcrystalline ductile micromechanism. An increase in carbon content is accompanied by a decline in ductility areas, whilefracture of specimens is of mixed nature: ductile and brittle. After ageing, only cases of mixed fracture were observed.Исследовано влияние повышенного содержа­ния углерода и параметров термообработки на микроструктуру и некоторые свойства ферритоаустенитной литой двухфазной ста­ли. Из экспериментальных результатов сле­дует, что микроструктура литой стали после термической обработки на твердый раствор существенно изменяется при повышении содержания углерода. Процесс старения стали после термической обработки на твер­дый раствор приводит к примерно 20%- ному повышению твердости и снижению ударной прочности в несколько раз. Фрактографические исследования показывают, что для поверхностей разрушения образцов из стали с низким содержанием углерода ха­рактерным является транскристаллитный вязкий микромеханизм разрушения. Повы­шение содержания углерода сопровождается уменьшением удельной доли зон пластичес­кого разрушения и проявлением смешанного (хрупкого и вязкого) разрушения образцов. После старения стали наблюдался лишь смешанный характер разрушения