Wyniki wyszukiwania - Biblioteka Nauki

1

Modelling of structure changes in TRIP type steel during hot deformation

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Adamczyk M. , Kuc D. , Hadasik E.

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2008

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tom Vol. 8, no 3

5-13

EN

Physical modelling of the changes occurring in the structure of low-alIoy C-Mn-AI TRIP-aided steel during hot-rolling were presented in this paper. An influence of deformation and controlIed cooling parameters on the microstructure of the tested steel was determined. MetalIographic research showed continuous refinement of structure in consecutive stage of deformation. Applied parameters of cooling allowed obtaining multi-phase structure containing ferrite, bainite, and also retained austenite.

PL

W pracy dokonano oceny wpływu parametrów odkształcenia oraz kontrolowanego chłodzenia na mikrostrukturę niskostopowej stali C-Mn-AI typu TRIP. Przyjęte parametry poszczególnych odkształceń pozwoliły na uzyskanie jednorodnej struktury o wielkość ziarna austenitu [...]. Obniżenie prędkości chłodzenia w zakresie dwufazowym wpływa istotnie na wzrost udziału tej fazy w strukturze końcowej. Chłodzenie z prędkością 4 °C/s w zakresie [...] pozwoliło na uzyskanie drobnoziarnistej struktury o korzystnym udziale poszczególnych faz. Stabilny austenit szczątkowy o udziale do -15% zlokalizowany jest na granicach ziarn oraz w postaci drobnych obszarów pomiędzy listwami bainitu. Otrzymana w strukturze ilość bainitu oraz austenitu szczątkowego wpływa umacniająco, natomiast frakcja ferrytu powinna zapewnić odpowiednią ciągliwość podczas dalszego kształtowania na zimno.

2

Badania właściwości nowoczesnych blach karoseryjnych ze stali typu TRIP

100%

Siodłak D. , Kawalla R.

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2009

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tom Vol. 76, nr 6

372-377

PL

Celem pracy było określenie mikrostruktury i właściwości mechanicznych nowoczesnej niskostopowej stali typu TRIP wytwarzanej po walcowaniu na zimno i wyżarzaniu w linii ciągłego cynkowania ogniowego. Udokumentowano mikrostruktury i właściwości mechaniczne tej stali na różnych etapach komercyjnej produkcji przemysłowej: w stanie gorącowalcowanym oraz zimnowalcowanym bez wyżarzania.

EN

The objective of this work was to determine the microstructure and the mechanical properties of modern low alloy TRIP steel, which is manufactured in the industrial practice in the hot dip galvanized line. The microstructures and the mechanical properties in each stage of the industrial production: hot rolled and cold rolled not annealed condition were investigated.

3

Microstructure evaluation of TRIP steel used in a car crash zones

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Oleksova M. , Slota J. , Herditzky A.

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2010

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tom z. 81 [277]

45-50

EN

The paper deals with evaluation of TRIP (transformation induced plasticity) steel microstructure. These special steels are commonly used mainly in automotive industry for crash zones of car's bodies. The TRIP steel has high strength compared to AHSS steel, but on the other hand a good plastic properties. The microstructure properties of TRIP steel were investigated by a light microscope and evaluated by a computer program ImageJ. Microstructure charakteristics of TRIP steel was investigated on shape-complicated part made by deep drawing process.

4

Intercritical annealing with isothermal holding of TRIP CMnAlSi steel

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Gajda B. , Lis A. K.

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2007

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tom Vol. 20, nr 1-2

439-442

EN

Purpose: The purpose was to obtain the TRIP microstructure in the modern CMnAlSi steel, after cooling from the temperature 850 degrees centigrade. Samples were continuously cooled with rate 20 degrees centigrade/s to the R.T. or isothermally annealed in the bainitic transformation range during 600s at 500, 450 and 400 degrees centigrade. The influence of cooling type on microstructure and amount of retained austenite were investigated. Design/methodology/approach: Dilatometric experiments of the CMnAlSi steel were done. Microstructure were investigated by light optical microscopy OM and scanning electron microscopy SEM. The amounts of retained austenite were investigated with X-ray diffraction technique and LePera color etching method. Quantitative analyses of phases were done using Image pro Plus program. Vickers hardness HV10 measurements were done. Findings: The TRIP type microstructure can be obtained for the investigated steel through continuous cooling from 850 degrees centigrade/60s or after cooling with the isothermal holding at the bainitic transformation temperatures range. The highest amount of austenite (-12%) was observed in samples isothermally annealed at the temperatures 450/600s and 400 degrees centigrade/600s. Practical implications: Steel CMnAlSi is well suited for production of TRIP grade in a large range of isothermal holding temperatures from 500 to 400 degrees centigrade and also after continuous cooling with the rate 20 degrees centigrade/s to the R.T. The amount of 39% austenite at temperature 850 degrees centigrade allows for production of TRIP microstructure with stable retained austenite. Originality/value: The additions of Al and/or Si to the CMn steels have the influence on Ac1 and Ac3 temperatures, morphology of bainite and on stability of retained austenite in the TRIP steels. Therefore it is important to determine the heat treatment parameters for each grade of TRIP steels to obtain optimal microstructure with good mechanical properties for such applications as car bodies and car parts.

5

Wpływ obróbki cieplno-plastycznej na morfologię austenitu szczątkowego w stali wielofazowej typu C-Mn-Si-Al-Nb-Ti

84%

Grajcar A. , Radwański K.

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2010

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tom Vol. 77, nr 8

384-388

PL

W pracy dokonano analizy cech mikrostrukturalnych austenitu szczątkowego w stali wielofazowej typu 0,24C-1,5 Mn-0,9Si-0,4Al z mikrododatkami Nb i Ti po obróbce cieplno-plastycznej. Analizę morfologii, wielkości i rozmieszczenia austenitu szczątkowego w osnowie ferrytycznej przeprowadzono z zastosowaniem techniki EBSD. Stwierdzono, że austenit szczątkowy ma kształt blokowych, nieregularnych ziarn o wielkości od 0,4 do 7 žm2 lub filmów, ulokowanych pomiędzy płytkami ferrytu bainitycznego. Austenit szczątkowy wykazuje zależności krystalograficzne z sąsiadującymi obszarami ferrytu bainitycznego.

EN

The analysis of microstructural features of retained austenite in a 0.24C-1.5 Mn-0.9Si-0.4Al type multiphase steel with Nb and Ti microadditions after the hermomechanical processing was performed in the work. The analysis of the morphology, size and distribution of retained austenite in a ferritic matrix was carried out by the use of the EBSD technique. It was found that retained austenite has a shape of block, irregular grains with a size from 0.4 to 7 ěm2 or films located between bainitic ferrite laths. The retained austenite fulfils crystallographic relationships with neighbouring regions of bainitic ferrite.

6

Rozwój struktury stali typu TRIP podczas obróbkiplastycznej na gorąco

84%

Grojcar A. , Opiela M.

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tom Vol. 75, nr 8

402-404

PL

W pracy zbadano zachowanie się nowo opracowanej stali C-Mn-Si-Al z mikrododatkami Nb i Ti w warunkach obróbki plastycznej na gorąco. Wyznaczono krzywe a-e oraz ujawniono strukturę austenitu pierwotnego próbek odkształconych do zadanego odkształcenia plastycznego oraz wytrzymanych izotermicznie po odkształceniu przez 10 s. Na tej podstawie wyznaczono warunki kilkuetapowego ściskania symulującego końcowe przepusty walcowania.

EN

Behaviour of new-developed C-Mn-Si-Al steel with Nb and Ti microadditions in hot-working conditions was investigated in the work The o-e curves were determined and primary austenite structures of the specimens deformed to a given strain and isothermally held for 10 s after deformation were revealed. On this basis, the conditions of multistage compression simulating final rolling passes were determined.

7

Effects of Mn and Nb on the macro- and microsegregation in high-Mn high-Al TRIP steels

84%

Grajcar A. , Kalinowska-Ozgowicz E. , Opiela M. , Grzegorczyk B. , Gołombek K.

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2011

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tom Vol. 49, nr 1

5-14

EN

Purpose: The aim of the paper is to determine the effects of Mn and Nb on the macro- and microsegregation of new-developed (3-5)Mn 1.5Al TRIP steels in the as-cast state and after hot forging. Design/methodology/approach: To assess possible macro- and microsegregation the chemical composition was investigated in the macro scale by OES and by the use of EDS in microregions. To reveal the macrostructure the ingots were etched by Oberhoffer’s reagent. The chemical composition along a diameter of the ingots was tested as well as in different regions of the plastically deformed flats. Metallographic investigations were carried out using optical (OM) and scanning electron microscopy (SEM). Findings: The Mn and Nb contents have significant effects on the obtained bainitic-martensitic structures and the morphology of retained austenite. The tendency to macrosegregation of Mn and Al between middle and external parts of the as-cast ingots and hot forged flats was detected. The Nb micoalloying results in the overall refinement of obtained microstructures and reduces the identified segregation of Al and Mn. A little microsegregation of these alloying elements between structural constituents was also detected. Research limitations/implications: Further investigations to describe in detail the identified structural constituents and the tendency of alloying elements to segregation in the thermomechanically rolled sheets are in progress. Practical implications: The knowledge of the macro- and microsegregation of Mn and Al in the TRIP steels with a high fraction of retained austenite is of primary importance for the manufacturing paths of these multiphase structure steels. Originality/value: A problem of segregation of Al and Mn in advanced high strength steels with and without Nb microaddition was described and interesting types of bainitic structures were identified.

8

Laboratory simulation of hot rolling of TRIP steel in the two-stand Steckel mill

67%

Chlopnik R. , Pesa J. , Janosec M. , Schndler I. , Rusz S. , Legierski M.

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tom Vol. 75, nr 8

502-505

EN

The aim of the performed laboratory simulations was to verify chances of the production of hot rolled strips from a TRIP steel in conditions of the reversible rolling in the two-stand Steckel rolling mill. The unique experimental equipment was used for conducting these simulations. The laboratory hot rolled strips from the TRIP steel underwent subsequently the mechanical and microscopic analysis, which confirmed a possibility of processing this steel in the given type of rolling mills.

PL

Celem przeprowadzonych fizycznych symulacji było sprawdzenie możliwości produkcji blach taśmowych walcowanych na gorąco ze stali TRIP w warunkach nawrotnego walcowania w dwuklatkowej walcarce Steckla. Symulacje przeprowadzono na unikatowych urządzeniach laboratoryjnych. Badania właściwości mechanicznych i analiza mikroskopowa potwierdziły możliwość wytwarzania blach taśmowych ze stali TRIP w tego typu walcarkach.