Wyniki wyszukiwania - BazTech

1

Effect of Non-Metallic Inclusions on the Hot Ductility of High-Mn Steels

Opiela Marek, Fojt-Dymara Gabriela

Advances in Science and Technology. Research Journal

|

2023

|

Vol. 17, no 3

19--30

EN

The aim of the work was to determine the effect of non-metallic inclusions on the hot ductility of two newly developed high-Mn austenitic steels (27Mn-4Si-2Al and 24Mn-3Si-1.5Al-Ti). For this purpose, a hot tensile test was carried out in the temperature range from 1050°C to 1200°C with a constant strain rate of 2.5⸱10-3 s-1. The tests were performed on the Gleeble 3800 thermomechanical simulator. Hot ductility of tested steels was defined by determining the reduction in area (% RA). Examined steels demonstrate diversified hot ductility. Clearly higher hot ductility was noted for the 24Mn-3Si-1.5Al-Ti steel. The reduction in area of this steel in the temperature range from 1050°C to 1200°C decreases from approx. 90% to about 58%, while the reduction in area of the 27Mn-4Si-2Al steel, in the same temperature range, decreases from approx. 66% to about 34%. The presence of single, regular-shaped AlN particles and complex MnS-AlN-type non-metallic inclusions was revealed in the 27Mn-4Si-2Al steel. Whereas fine (Ce, La, Nd)S-type sulphides, properly modified with rare earth elements, were identified in the 24Mn-3Si-1.5Al-Ti steel. The AlN-type inclusions and complex MnS-AlN-type inclusions were not revealed in the 24Mn-3Si-1.5Al-Ti steel. This is due to the presence of Ti microaddition, the concentration of which guaranteed binding of the whole nitrogen into stable TiN-type nitrides. Sulphides, disclosed in the 24Mn-3Si-1.5Al-Ti steel, are globular or slightly elongated in the direction of plastic deformation, as confirmed by a very low value of the elongation factor equal 1.48. This creates the opportunity to produce sheets of high strength and ductility and low anisotropy of mechanical properties.

2

Structure and mechanical properties of newly-developed high-strength TRIPLEX type steels

Sozańska-Jędrasik L., Mazurkiewicz J., Borek W., Dobrzański L. A.

Inżynieria Materiałowa

|

2018

|

Vol. 39, nr 5

184--191

EN

The paper presents the results of mechanical properties research, fractographic investigations of fractures and microstructure of experimental high-strength high-manganese X98MnAlSiNbTi24–11 and X105MnAlSi24–11 TRIPLEX type steels. In order to determine the mechanical properties of the tested steels, microhardness tests and a static tensile test were performed, and yield stress, tensile strength and elongation of the tested steels were determined. The performed microstructure tests of the analysed steels using light microscopy allowed for the identification of austenitic-ferritic structure with the participation of carbides. It was found that the structure of both tested steels, which have undergone hot rolling followed by water cooling, consist of austenite grains with numerous annealing and deformation twins along with ferrite bands. The investigated steels are characterized by the mixed fractures of formed after a static tensile test after forging where there are areas of ductile fracture with small areas of transcrystalline and intergranular brittle fractures. The fractures after a static tensile test and after hot rolling and cooling in water have a dimple morphology characteristic of plastic fractures. The increase in hardness after thermomechanical treatment and after a static tensile test is caused by strain hardening affecting the achieved values of strength, yield point and hardness. The obtained research results allow to assess the impact of both the chemical composition and the applied thermomechanical treatment technology on the properties of newly developed steels.

PL

Celem pracy było określenie właściwości mechanicznych oraz plastycznych w powiązaniu z mikrostrukturą nowoopracowanych stali wysokomanganowych X98MnAlSiNbTi24–11 i X105MnAl- Si24–11 typu TRIPLEX po walcowaniu na gorąco w skali półprzemysłowej i chłodzeniu w wodzie. Uzyskane wyniki badań pozwolą na ocenę wpływu zarówno składu chemicznego, jak i zastosowanej technologii obróbki cieplno-mechanicznej na właściwości badanych stali.

3

Carbides Analysis of the High Strength and Low Density Fe-Mn-Al-Si Steel

Sozańska-Jędrasik L., Mazurkiewicz J., Borek W., Matus K.

Archives of Metallurgy and Materials

|

2018

|

Vol. 63, iss. 1

265--276

EN

The work presents the results of investigations into the structure and phase composition of newly developed high manganese steels of the X98MnAlSiNbTi24-11 and X105MnAlSi24-11 type. The average density of such steels is 6.67 g/cm3, which is 15% lower as compared to typical structural steels. An analysis of phase composition and structure allows to conclude that the investigated steels feature an austenitic γ-Fe(Mn,Al,C) structure with uniformly distributed and elongated α-Fe(Mn,Al) ferrite grains on the boundaries of austenite grains and carbides. Examinations by diffraction of back scattered electrons (EBSD) allow to conclude that high-angle boundaries dominate in such steels, having significant influence on mechanical properties. Three types of carbides with differentiated chemical composition and size were identified in steel X98MnAlSiNbTi24-11 with scanning and transmission electron microscopy. κ-(Fe,Mn)3AlC carbides, having a regular, face-centered cubic lattice (fcc), were identified in austenite. Transmission electron microscopy examinations have enabled to identify M7C3-type carbide in ferrite. Nb- and Ti-based complex carbides were identified in steel X98MnAlSiNbTi24-11, both, in ferrite and austenite. (NbTi)C2 carbide precipitates were confirmed in an X-ray qualitative phase analysis. The size of the above-mentioned carbides is within several to several dozens of μm. An X-ray qualitative phase analysis has confirmed the precipitates of M7C3 carbides in both steels.

4

Structure and phase composition of newly developed high manganese X98MnAlSiNbTi24–11 steel of TRIPLEX type

Sozańska-Jędrasik L., Mazurkiewicz J., Borek W., Dobrzański L. A.

Inżynieria Materiałowa

|

2017

|

Vol. 38, nr 2

69--76

EN

The work presents the results of investigations of the structure and phase composition of newly developed high manganese X98MnAlSiNbTi24–11 steel of TRIPLEX type. The average density of such steel is 6.67 g/cm3, which is less than for typical structural steels by even 15%. A preliminary analysis of phase composition and structure allows to find an austenitic γ-Fe(Mn, Al, C) structure in the investigated steel with uniformly distributed ferritic α-Fe(Mn, Al) areas elongated towards the boundaries of austenite grains and numerous carbides with differentiated chemical composition and varied size. Nb- and Ti-based complex carbides are dominant in the steel. The investigations of the chemical composition of the carbides revealed in the matrix allow to identify with high probability dispersive κ-(Fe, Mn)3AlC carbides with the nanometric size of approx. 10÷160 nm, which has to be yet confirmed with electron transmission microscopy methods. Fe, Mn and Al as well as small amounts of Nb, Ti and Si are contained in such carbides. The occurrence of aluminium carbonitrides with a fraction of Nb and Ti was also revealed. The size of the above Nb and Ti carbides revealed in solid specimens in the matrix of the studied steel is between approx. 10 nm to 15 μm. X-ray diffraction examinations of carbide isolates prepared by the method of chemical dissolution in HCl showed the existence of NbTiC2 carbides in the studied steel. The diffraction examinations of solid specimens revealed, apart from austenite and ferrite, also the existence of TiC carbides and such initially classified as Mn3.6C0.4 type.

PL

Celem pracy była charakterystyka struktury i składu fazowego nowoopracowanej stali wysokomanganowej X98MnAlSiNbTi24–11 typu TRIPLEX zawierającej dodatki stopowe Ti i Nb przy dużej zawartości węgla.

5

Ocena wpływu dynamicznego odkształcania z wykorzystaniem młota spadowego na podatność do odkształceń plastycznych wybranych stali wysokomanganowych

Jabłońska M., Tomaszewska A., Kuc D., Śmiglewicz A.

Hutnik, Wiadomości Hutnicze

|

2016

|

Vol. 83, nr 8

337--339

PL

Coraz częściej w przemyśle motoryzacyjnym wymaga się stosowania nowych materiałów o właściwościach przewyższających stosowane obecnie. Z tego powodu duże zainteresowanie wzbudzają stale z grupy Advanced High Strenght Steel (AHSS), a w tym średnio i wysokomanganowe z dodatkami Al i Si. Stale te w zależności od zawartości Mn i Al wykazują skłonność do odkształcenia w oparciu o szczególne mechanizmy zależne od wartość energii błędu ułożenia austenitu EBU. W przypadku stali mających swe zastosowanie na elementy pojazdów pochłaniające energię zderzenia doskonałe właściwości wykazują stale austenityczne umacniane wskutek mechanicznego bliźniakowania oraz stale dwufazowe austenityczno-ferrytyczne. W niniejszej publikacji przedstawiono wyniki badań wpływu odkształcania dynamicznego za pomocą młota spadowego na podatność do odkształcenia plastycznego wybranych gatunków stali wysokomanganowej. Przeprowadzono próby odkształcania z prędkością 7,67 m/s elementów w postaci podłużnicy samochodowej i dokonano analizy wpływu tego procesu na zmiany wymiarów i kształtu z uwzględnieniem oceny mikrostruktury w obszarze działania największych naprężeń ściskających i rozciągających.

EN

Increasingly in the automotive industry it requires the use of new materials with properties exceeding the materials used today. For this reason, they arouse great interest the steels from the group of Advanced High Strength Steel (AHSS), in the medium and high manganese with additions of Al and Si. These steels, depending on the contents of Mn and Al have a tendency to deform based on the specific deformation mechanisms depending on the value of the stacking fault energy. In the case of steels having their application to components vehicle energy-absorbing excellent properties show austenitic steels strengthened as a result of mechanical twinning and continuously two phase austenitic-ferritic. This publication presents the results of research on the impact of dynamic deformation using a drop hammer on the susceptibility to plastic deformation of selected species of high manganese steel. Tests were carried out with a strain speed of 7.5 m/s components in the form of car stringer and an analysis of the impact of this process on the changes in the dimensions and shape including an evaluation of the microstructure within the area of largest compressive and tensile stresses.

6

Mechanical Properties of High-Mn Austenitic Steel Tested under Static and Dynamic Conditions

Dobrzański L. A., Borek W., Mazurkiewicz J.

Archives of Metallurgy and Materials

|

2016

|

Vol. 61, iss. 2A

725--730

EN

The purpose of the paper is to investigate X73MnSiAlNbTi25-1-3 high manganese austenitic steel containing 0.73% C to determine structural mechanisms decisive for increasing a reserve of cold deformation energy of such steel. The influence of a strain rate on the structure of the investigated steels and on the structural mechanisms decisive for their properties was analysed. Specialist research instrumentation was used for this purpose such as Scanning Transmission Microscopy (including EBSD examinations), conventional and high-resolution transmission electron microscopy together with diffraction examinations and metallographic examinations. It was found that the principal cause of an increased reserve of cold deformation energy of the investigated steels in dynamic conditions is the activation of mechanical twinning in the mutually intersecting systems in austenite grains and annealing twins, which are densifying when a cold deformation rate is growing, thereby confirming the basic mechanism of TWIP (TWinning Induced Plasticity).

7

TWIP mechanism in processing of high-manganese austenitic steel

Dobrzański L. A., Borek W., Mazurkiewicz J.

Journal of Achievements in Materials and Manufacturing Engineering

|

2015

|

Vol. 71, nr 1

22--27

EN

Purpose: The aim of this paper is to determine the high-manganese austenite propensity to twinning induced by the cold working and its effect on structure and mechanical properties, and especially the strain energy per unit volume of new developed high-manganese Fe-Mn-(Al,Si) high-manganese austenitic TWIP (TWinning Induced Plasticity) steel containing about 25% Mn, 1% Si, 3% Al. Design/methodology/approach: The essence of the research concerns the analysis of the influence of microstructure evolution during cold plastic deformation. The microstructure of investigated steel was determined in metallographic investigations using light, scanning and high- resolution transmission electron microscopies (HRTEM). Findings: The activation of intensive mechanical twinning mechanisms in high-manganese austenitic steels, in order to increase strain energy, allows the formation of technological components of complex shape or permits the discharge of energy during cold plastic deformation. According to currently presented views, it is believed that the new austenitic steels with the A1 crystallographic structure containing Mn more than 25 mass.%, Si and Al can provide a significant advance, particularly in automotive applications, because practically there are no more possibilities to improve at the same time the strength and ductility of the steel with A2 crystallographic structure. Research limitations/implications: Results obtained in static conditions for new developed high-manganese austenitic steel indicate the possibility and purposefulness of their employment for constructional elements of vehicles, especially of the passenger cars to take advantage of the significant growth of their strain energy per unit volume which guarantee reserve of plasticity in the zones of controlled energy absorption during possible collision resulting from activation of twinning induced by cold working, which may lead to significant growth of the passive safety of these vehicles' passengers. Originality/value: TWIP steels show not only excellent strength, but also have excellent formability due to twinning, thereby leading to an excellent combination of strength, ductility, and formability over conventional dual-phase steels.

8

Mechanical Properties and Fractographic Analysis of High Manganese Steels After Dynamic Deformation Tests

Jabłońska M. B.

Archives of Metallurgy and Materials

|

2014

|

Vol. 59, iss. 3

1193--1197

EN

Since few years many research centres conducting research on the development of high-manganese steels for manufacturing of parts for automotive and railway industry. Some of these steels belong to the group of AHS possessing together with high strength a great plastic elongation, and an ideal uniform work hardening behavior. The article presents the dynamic mechanical properties of two types of high manganese austenitic steel with using a flywheel machine at room temperature with strain rates between 5×102 ÷3.5×103 s-1 . It was found that the both studied steels exhibit a high sensitivity Rm to the strain rate. With increasing the strain rate from 5×102 to 3.5×103 s-1 the hardening dominates the process. The fracture analysis indicate that after dynamic test both steel is characterized by ductile fracture surfaces which indicate good plasticity of investigated steels.

PL

Od kilku lat wiele ośrodków badawczych prowadzi prace nad rozwojem stali wysokomanganowych przeznaczonych do produkcji części dla przemysłu samochodowego i kolejowego. Niektóre z tych stali należą do grupy nazywanej Advanced High Strength Steels, i charakteryzują się wysoką wytrzymałością przy jednocześnie bardzo dużej plastyczności i szerokim zakresie umocnienia. W niniejszej pracy przedstawiono badania właściwości mechanicznych w próbach odkształcenia dynamicznego dla dwóch gatunków wyskomanganowej stali austenitycznej z wykorzystaniem młota rotacyjnego w temperaturze pokojowej z szybkością odkształcenia między 5 x 5×102 ÷3.5×103 s-1. Stwierdzono, że badane stale wykazują wysoką czułość wytrzymałości na rozciąganie Rm na prędkość odkształcenia. Wraz ze wzrostem szybkości odkształcenia od 5×102 do 3.5×103 s-1 następuje proces umocnienia badanych stali. Przeprowadzona analiza faktograficzna przełomów wskazuje, że pękanie po próbach dynamicznej deformacji obu stali ma charakter transkrystaliczny ciągliwy co wskazuje na wysoką plastyczność badanych stali.

9

Microstructure based flow curve modeling of high-Mn steels with TWIP and TRIP effect

Twardowski R., Prahl U.

Computer Methods in Materials Science

|

2012

|

Vol. 12, No. 3

130--136

EN

In the present work a microstructural model based on representative volume elements (RVE) is proposed for high manganese steels with TWIP and TRIP effect. The polycrystalline structure is generated by spatial discretization of the RVE in three-dimensional Voronoi tessellations. For the hardening behavior a constitutive material model is used based on the evolution of dislocation, twin and epsilon-martensite density. The plastic deformation is investigated numerically using periodic displacement boundary conditions. In addition to the parameters of temperature and microstructure the influence of the chemical heterogeneity is investigated. The experimental verification of the numerical results is done by uniaxial tensile tests on flat tensile speciems.

XX

W pracy zaproponowano model krzywych płynięcia stali z efektem TWIP i TRIP, wykorzystujący ideę reprezentatywnego elementu objętości (ang. representative volume element -RVE). Strukturę polikryształu wygenerowano poprzez dyskretyzacją przestrzeni z zastosowanie wieloboków Voronoi. Do opisu umocnienia materiału wykorzystano model wykorzystujący ewolucję populacji dyslokacji, bliźniakowanie oraz gęstość martenzytu epsilon. Odkształcenie plastyczne analizowano numerycznie stosując okresowe warunki brzegowe w RVE. Oprócz uwzględnienia wpływu temperatury i prędkości odkształcenia rozważono też wpływ nierównomierności składu chemicznego. Weryfikację doświadczalną modelu przeprowadzono dla próby jednoosiowego rozciągania próbek płaskich.

10

Thermo-mechanical treatment of Fe–Mn–(Al, Si) TRIP/TWIP steels

Dobrzański L. A., Borek W.

Archives of Civil and Mechanical Engineering

|

2012

|

Vol. 12, no. 3

299--304

EN

Recent development in group of Fe–Mn–Al–Si steels with high-manganese content demands for more research in thermo-mechanical treatment and development of microstructure in such steels. Hot working conditions on forming the structure and course of the heat activated processes, removing the strain hardening effects, have been investigated. The chemical compositions of two high-manganese austenitic TRIP/TWIP steels containing various Mn concentrations were developed. Additionally, the steels were microalloyed by Nb and Ti in order to control the grain growth under hot-working conditions. The force-energetic parameters of hot-working were determined in continuous and multi-stage compression test performed in temperature range from 850 to 1100 °C and strain rate of 0.1, 1, 10 s−1 using the Gleeble 3800 thermo-mechanical simulator. The microstructure of investigated steels was determined in metallographic investigations using light microscope as well as X-ray diffraction. It was found that the thermo-mechanical treatment conditions have no influence on phase composition of the investigated steels.

11

Struktura i wybrane właściwości wysokomanganowych stali przeznaczonych dla przemysłu motoryzacyjnego

Jabłońska M., Śmiglewicz A., Tomaszewska A.

Hutnik, Wiadomości Hutnicze

|

2010

|

Vol. 77, nr 8

400-402

PL

W ostatnich latach ośrodki badawcze w kraju i na świecie koncentrują swoje prace badawcze w obszarze rozwoju wysokomanganowych stali przeznaczonych dla przemysłu motoryzacyjnego. Zależnie od zawartości Mn, Al i Si stale te wykazują różną EBU, a tym samym odrębny mechanizm odkształcenia, taki jak indukowana odkształceniem przemiana martenzytyczna (efekt TRIP) i indukowane odkształceniem bliźniakowanie (efekt TWIP). W artykule analizowano zmiany plastyczności w funkcji temperatury odkształcania, wyznaczając temperaturę zerowej plastyczności stali FeMnAlSi. Ponadto przeprowadzono badania faktograficzne. Powierzchnię przełomów badano za pomocą skaningowego mikroskopu elektronowego.

EN

In recent years considerable efforts have been directed to the development of high-Mn steels for a automotive industry. For a value of Mn, Al, and Si addition those steels have a unequal value of EBU and a different stress mechanism like twinning induced plasticity TWIP and transformation induced plasticity TRIP. In this article was analyzed plasticity test with a function of stress temperature calculated a zero plasticity temperature of FeMnAlSi steel. Moreover a factography investigations was made. Fracture surface was examined in the scanning electron microscope.