Wyniki wyszukiwania - Biblioteka Nauki

1

Selected Problems of the Microstructure Evolution During Microalloyed Steel Wire Rod Production Process

100%

Kwiecień M. , Graca P. , Muszka K. , Majta J.

Archives of Metallurgy and Materials

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2017

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tom Vol. 62, iss. 2A

899--904

EN

In the present study, we have discussed the selected problems of microstructure development during the whole manufacturing process, i.e. continuous casting, thermomechanical processing, and cold metal forming of the microalloyed steels wires. In the investigated steels, the microstructure development was controlled by the history of deformation and by the effects of microalloying elements, mostly Nb, Ti, and B. It has been concluded that obtained in the ultrafine grained microalloyed steel wires mechanical properties were first of all resulting from specific structural composition and grain refinement. Additionally, it has been proven that austenite grain refinement, that increases nucleation rate during the austenite-to-ferrite phase transformation, as a result of the thermomechanical processing, are very beneficial from point of view of the final mechanical properties. This problem starts to be very important when the microalloyed steel products are subjected to severe plastic deformation, as it has been shown discussed in the present work for combined processes of wire drawing and wire flattening.

2

Effect of Heat Treatment on Mechanical Properties and Microstructure Morphology of Low-Alloy High-Strength Steel

100%

Bolanowski K.

Archives of Metallurgy and Materials

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2016

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tom Vol. 61, iss. 2A

475--480

EN

The paper analyzes the influence of different heat treatment processes on the mechanical properties of low-alloy high-strength steel denoted by Polish Standard (PN) as 10MnVNb6. One of the findings is that, after aging, the mechanical properties of rolled steel are high: the yield strength may reach > 600 MPa, and the ultimate tensile strength is > 700 MPa. These properties are largely dependent on the grain size and dispersion of the strengthening phase in the ferrite matrix. Aging applied after hot rolling contributes to a considerable rise in the yield strength and ultimate tensile strength. The process of normalization causes a decrease in the average grain size and coalescence (reduction of dispersion) of the strengthening phase. When 10MnVNb6 steel was aged after normalization, there was not a complete recovery in its strength properties.

3

Influence of cooling rate on microstructure of a NB-V HSLA steel

100%

Legerski M. , Schindler I. , Suchánek P.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

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2007

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tom Vol. 321, z. 89

115-116

EN

In most cases an effort is made to combine controlled rolling of the microalloyed steel with its accelerated cooling, which has a favourable influence mainly on size of the resulting ferritic grain. In practice an opposite case may sometimes happen, where even slowed down cooling of final rolled products occurs. For example, after rolling of universal mill plates in a three-high mill the rolled products are not water-sprayed but they cool from the finish rolling temperature in collection pits, where accumulation of a larger quantity of the hot material strongly reduces speed of cooling down the material, compared also with free cooling in the air. In laboratory experiments mentioned below a simplified simulation of controlled finish rolling and slowed down cooling of such universal mill plates was carried out.

4

Relationship between microstructure and mechanical properties of strips from microalloyed steel after cold rolling and annealing

100%

Janošec M. , Schindler I. , Vodárek V. , Místecký E. , Růžička M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2007

|

tom Vol. 321, z. 89

105-106

EN

A large testing programme of an HSLA strip steel grade S 500 MC was conducted. The experiment was based on combination of cold rolling, recrystallization annealing, mechanical testing and metallographic examinations. Samples of pickled cuts of hot rolled strip of thickness 4 mm were used for simulation by rolling. Chemical composition of the steel grade was as follows: 0.06 C - 1.38 Mn- 0.24 Si - 0.013 P - 0.005 S - 0.022 Al - 0.03 V - 0.02 Ti - 0.07 Nb (wt %). Samples in the form of strips with dimensions 4 x 25 x 340 mm were rolled in several passes with total height reduction 5 to 75 %. Particular partial strains were realized at room temperature in the housingless, hydraulically pre-stressed laboratory mill QUO (a four-high mill with work rolls of diameter 62 mm) [1]. Afterwards the laboratory mill products were annealed in the vacuum furnace with the protective gas atmosphere consisting of N2+H2. The annealed samples underwent the mechanical testing. The gained results yield stress YS, ultimate tensile strength UTS and their ratio, as well as elongation Ago in %, were summarized in graph (see Fig. 1) in dependence on relative height reduction before annealing - 8 [%]. The found out points were plotted in a coordinate system and the corresponding curves were constructed manually. It was confirmed that by a suitable combination of size of previous cold deformation and parameters of the following recrystallization annealing it is possible to influence a complex of mechanical properties of particular strips. Particular trends of strength and plastic properties correspond to each other. These trends are caused by structure-forming processes (deformation strengthening, recrystallization) which were documented by micrographs (see Fig. 2 for example). Values of strength properties may be influenced by the described way in the range of approximately 100 MPa, which enables - related to applications in practice -to use the obtained results in formation of technological procedures of forming and heat treatment in cold rolling mills.

5

Hydrogen diffusion in micro alloy steels

100%

Sojka J. , Jonšta P. , Rytířová L. , Jerome M. , Zajac J. , Sozanska M.

Zeszyty Naukowe. Mechanika / Politechnika Opolska

|

2007

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tom Vol. 321, z. 89

121-122

EN

Petroleum and natural gas systems can be contaminated with wet H2S. This environment is very aggressive to the steels used in the transport and processing of these products and it can result in various forms of hydrogen embrittlement. The reaction between wet H2S and the steel generates atomic hydrogen, which can be, at least partially, absorbed into the steel. In the absence of applied stress, the diffused hydrogen can cause hydrogen induced cracking (HIC). The resistance of steels to HIC is closely related to the microstructure features: nonmetallic inclusions, hard phase constituents, banded structures etc. In the presence of applied or residual stress, the failure process can occur by sulphide stress cracking (SSC) or stress oriented hydrogen induced cracking (SOHIC). In the case of SSC, steel resistance is commonly derived from its strength level. It is generally accepted that steels having tensile strength less than 690 MPa approx. are resistant to SSC. The role of microstructure is not emphasized although there are some works showing that microstructure can also play an important role in the case of SSC. In the previous works, it was proved that even in case of SSC the resistance of the steels can be improved by the heat treatment – quenching and tempering, if the banded structure of ferrite and pearlite is replaced by the tempered martensite and/or bainite. The resistance of the steel to the hydrogen embrittlement is affected by both the microstructure and hydrogen concentration. To understand the hydrogen embrittlement it is necessary to characterize also the hydrogen transport – diffusion. In this work hydrogen diffusion coefficient in micro alloy X52 and X60 API steels (tubes), having different microstructures - banded ferrite and pearlite after hot rolling and the mixture of tempered bainite and martensite after quenching and tempering, are evaluated. The role of specimen orientation is also taken into account.

6

Hydrogen Assisted Cracking in a Microalloyed Steel Subjected to a Rapid Thermal Cycle at High Temperature

100%

Lopez-Martinez E. , Vázquez-Gómez O. , Vergara-Hernández H. J. , Campillo B.

Archives of Metallurgy and Materials

|

2018

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tom Vol. 63, iss. 1

315--321

EN

In a martensitic-bainitic microalloyed steel, the effect of hydrogen on fatigue crack growth was studied using rotary bending fatigue tests. The steel was subjected to a rapid thermal cycle to get a microstructure similar to that which would be formed within the coarse-grained heat-affected zone of a weld. Crack growth was monitored as a function of the number of cycles applied during fatigue tests on three types of specimens: 1) those without hydrogen charge, 2) those charged with hydrogen and 3) those charged with hydrogen which was then discharged through low-temperature heat treatment. All types showed persistent slip marks, and cracks propagated along high-shear-stress planes. In the presence of hydrogen, crack growth was affected by microstructural defects caused by the hydrogen charging process, and the persistent slip marks developed in an area closer to the crack tip and crack path. On the contrary, without hydrogen, crack growth occurred perpendicular to the applied force, and the persistent slip marks were fewer in number and further from the crack tip and crack path. This indicates that the plasticity increased (i.e., the damage that occurred in the presence of hydrogen matched the hydrogen-enhanced local plasticity mechanism).

7

Influence of plastic deformation on CCT-diagrams of new-developed microalloyed steel

88%

Opiela M. , Zalecki W. , Grajcar A.

Journal of Achievements in Materials and Manufacturing Engineering

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2012

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tom Vol. 51, nr 2

78--89

EN

Purpose: The aim of the paper is to investigate the influence of plastic deformation and cooling conditions on a structure and a shape of CCT-diagrams of new-developed Nb-Ti-V microalloyed steel. Design/methodology/approach: The diagrams of undeformed and plastically-deformed supercooled austenite transformations for Nb-Ti-V microalloyed steel were determined. A part of the specimens were austenitized at a temperature of 885°C and next cooled to ambient temperature with a various rate from 234°C/s to 1°C/min. To investigate the influence of plastic deformation on a shape of CCT (Continuous Cooling Transformations) diagrams, another part of the specimens were 50% deformed at 885°C or 1100°C and cooled to ambient temperature with a rate from 95°C/s to 1°C/min. The DIL 805A/D dilatometer, with a LVDT-type measuring head, was used to carry out dilatometric test. Findings: Performed dilatometric research revealed that the steel is characterized with Ac3=843°C, Ac1=707°C and a relatively low Ms temperature equal 370°C. Plastic deformation of steel at the temperature of 885°C prior to the start of phase transformations results in distinct acceleration of pearlitic transformation and slight translation of bainitic transformation towards shorter times. Research limitations/implications: Elaborated curves of supercooled austenite transformations of studied steel fully predispose it to production of forgings quenched directly from forging finish temperature and successively subjected to high temperature tempering. Practical implications: The obtained CCT diagrams of supercooled plastically-deformed austenite transformations can be useful in determination of cooling condition of the thermo-mechanical processing for high strength forged machine parts obtained from microalloyed steels. Originality/value: The diagrams of the plastically-deformed supercooled austenite for a new-developed microalloyed steel were obtained.

8

HYDROGEN ASSISTED CRACKING IN A MICROALLOYED STEEL SUBJECTED TO A RAPID THERMAL CYCLE AT HIGH TEMPERATURE

88%

LÓPEZ-MARTÍNEZ E. , VÁZQUEZ-GÓMEZ O. , VERGARA-HERNÁNDEZ H. J. , Campillo B.

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nr 1

9

Modeling of the Kinetics of Carbonitrides Precipitation Process and Simulate the Image of Microstructure Using Cellular Automata Method in Microalloyed Steels

88%

Marynowski P. , Hojny M.

Archives of Metallurgy and Materials

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2022

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tom Vol. 67, iss. 3

1117--1124

EN

Microalloying elements such as Ti, Nb, V, entered into steel they influence their microstructure and mechanical properties, because formation of carbonitrides, M(C, N). Influence of carbonitrides to the microstructure and mechanical properties depends on their basic stereological parameters: volume fraction, Vv, and their size, r. In this work the Cellular Automata model of the kinetics of the carbonitrides precipitation which enable to predict the image of the microstructure and calculate the size of carbonitrides formed during isothermal annealing of supersaturated steel is presented. In the high temperature the microalloying elements inhibit the austenite grains growth. Chemical composition of steel has influence to volume fraction and size of precipitations. The work is supplemented with examples of experimental comparison.

10

Effects of Nb, Ti and V on recrystallization kinetics of austenite in microalloyed steels

88%

Opiela M. , Ozgowicz W.

Journal of Achievements in Materials and Manufacturing Engineering

|

2012

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tom Vol. 55, nr 2

759--771

EN

Purpose: The work presents research results of impact of Nb, Ti and V microadditions on flow stress, recrystallization kinetics and microstructure of newly elaborated steels assigned for production of forged machine parts, using the method of thermo-mechanical treatment. Design/methodology/approach: The study was performed with the use of Gleeble 3800 simulator. Stress-strain curves were determined during continuous compression test in a temperature range from 900 to 1100°C and at a strain rate of 1, 10 and 50 s-1. In order to determine recrystallization kinetics of plastically deformed austenite, discontinuous compression tests of specimens were done with a given strain at the rate of 10 s-1., in a temperature range from 900 to 1100°C, with isothermal holding of samples between successive stages of deformation for 2 to 100 s. Recrystallization kinetics of plastically deformed austenite was described using the Johnson-Mehl-Avrami equation. The observations of microstructures of thin foils were done using JEOL JEM 3010 transmission electron microscope. Findings: Basing on the analysis of the form and the course of curves obtained in the compression test, it was found that in the studied range of parameters of hot plastic deformation, the decrease of strain hardening of studied steels is caused by the process of continuous dynamic recrystallization. This is also confirmed by calculation results of activation energy of plastic deformation process. Performed two-stages compression tests revealed that microadditions introduced into steel considerably influence the kinetics of static recrystallization. Research limitations/implications: It was found that the time necessary for a total course of recrystallization of austenite is too long to be accepted in the production process of forgings. Practical implications: Executed hot compression tests will contribute to establishing conditions of forging with the method of thermo-mechanical treatment. Originality/value: Strain-stress curves and recrystallization kinetics curves of newly elaborated microalloyed steels have been determined.

11

Effect of grain refinement on mechanical properties of microalloyed steels

75%

Muszka K. , Majta J. , Bienias Ł.

Metallurgy and Foundry Engineering

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2006

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tom Vol. 32, no. 2

87-97

EN

The goal of the present work was to study the effect of grain size and strain rate on the mechanical properties of microalloyed steels. The range of the microstructures was developed and their mechanical properties were measured under quasi-static conditions. The influence of different thermomechanical parameters on grain refinement, and thus, on final mechanical behavior of these steels seems to be very important issue, because of their application as the materials with both high strength and ductility. There is a clear lack of understanding of the role of intermediate ultrafine microstructures on the mechanical response of structural steels, which is important as this is the refinement level most likely to be achieved under industrial processes. The main scope of this research includes the development of thermomechanical treatments to produce ultra fine-grained steels with enhanced properties. These materials will be developed for the application in many industries (e.g. automotive industry, shipbuilding), and in any commercial applications where very good properties and good-quality construction materials are of paramount importance. The results of this work will allow to systematically correlate the evolution of deformation microstructure and the deformation mechanisms operating in fine-grained materials during processing. This work will also be directed towards understanding the specific strengthening mechanisms by which the plastic deformation leads to a refined grain size.

PL

Celem przeprowadzonych badań jest ocena wpływu stopnia rozdrobnienia struktury na własności mechaniczne stali mikrostopowych. Uzyskano struktury o różnym stopniu rozdrobnienia, a następnie badano ich własności mechaniczne w warunkach quasi-statycznego obciążenia. Wpływ historii przeróbki termomechanicznej na rozdrobnienie mikrostruktury, a tym samym na końcowe własności mechaniczne, jest bardzo ważnym zagadnieniem ze względu na szeroki obszar zastosowań otrzymywanych tą drogą materiałów konstrukcyjnych. Jedną z cech charakterystycznych stali mikrostopowych jest korzystna kombinacja dobrych własności wytrzymałościowych i plastycznych. Zauważyć można brak badań w zakresie zrozumienia roli stopnia rozdrobnienia mikrostruktury w mechanice plastycznego płynięcia stali mikrostopowych. Istotny jest fakt, że dyskutowane w niniejszej pracy poziomy rozdrobnienia struktury ferrytycznej są już uzyskiwane w obecnie stosowanych procesach przemysłowych. Zakres przedstawionych badań obejmuje analizę procesów przeróbki termomechanicznej (kontrolowanego walcowania) pod kątem możliwości uzyskania struktur silnie rozdrobnionych. Konsekwencją silnego rozdrobnienia ferrytu jest możliwość istotnej poprawy własności mechanicznych. Badane w pracy, drobnoziarniste stale mikrostopowe znajdują coraz szersze zastosowanie w różnych gałęziach przemysłu (np. przemysł motoryzacyjny, stoczniowy), wszędzie tam gdzie istotne jest zastosowanie materiałów konstrukcyjnych o bardzo dobrej jakości i własnościach. Wyniki niniejszych badań pozwolą na usystematyzowanie powiązań pomiędzy rozwojem mikrostruktury a mechanizmami odkształcenia występującymi w materiałach drobnoziarnistych podczas procesu wytwarzania. Opracowane wnioski pozwalają na lepsze zrozumienie związków pomiędzy historią odkształcania a rozwojem mikrostruktury w stalach mikrostopowych.

12

Wytwarzanie blach grubych ze stali mikrostopowych w warunkach integracji odlewania ciągłego i obróbki cieplno-mechanicznej

75%

Adamczyk J.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika

|

2000

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tom Z. 72

145-154

PL

W pracy ustalono warunki obróbki cieplno-mechanicznej blach grubych o wysokiej wytrzymałości ze spawalnej stali niskostopowej do ulepszania cieplnego z mikrododatkami Nb, T i B na podstawie badań procesu odkształcenia plastycznego na gorąco i kinetyki rekrystalizacji statycznej austenitu. Wytworzone w tych warunkach blachy osiągają po wysokim odpuszczeniu bardzo dobrą odporność na pękanie w temperaturze obniżonej, znacznie większą niż po konwencjonalnym walcowaniu i ulepszaniu cieplnym. W celu obniżenia kosztów wytwarzania istnieje pełna możliwość integracji opracowanej metody obróbki cieplno-mechanicznej z ciągłym odlewaniem wlewków.

EN

Based on research results of hot plastic deformation processes and static recrystallization kinetics of austenite conditions of thermo - mechanical treatment high strength , low-alloy Nb, Ti and B microalloyed welding steel for thermal treatment were worked out. After a high - temperature, exceeding considerably the plate properties obtained after conventional rolling and heat treatment. To minimize overheads there exists a possibility of full integration of the being elaborated method of thermo - mechanical treatment with the continous casting of steel.

13

Wpływ prędkości odkształcania na naprężenie uplastyczniające stali mikrostopowych

75%

Stefańska-Kądziela M.

Hutnik, Wiadomości Hutnicze

|

2006

|

tom Vol. 73, nr 11

500-505

PL

W pracy przedstawiono rolę prędkości odkształcania w procesach przeróbki plastycznej oraz wyniki badań doświadczalnych i obliczeń modelowych stali mikrostopowej z dodatkiem Nb. Procesy osiowosymetrycznego spęczania przeprowadzono w różnej temperaturze z różnymi wielkościami i prędkościami odkształcenia. Wyniki doświadczalne przedstawiono w postaci krzywych płynięcia. Do obliczeń modelowych naprężenia uplastyczniającego wykorzystano zmodyfikowany model Zerilli’ego-Armstronga. Wykazano, że przyjęty model właściwie odzwierciedla warunki rzeczywiste procesu odkształcania i może być wykorzystywany do symulacji komputerowej procesów przeróbki plastycznej realizowanych z bardzo dużymi prędkościami odkształcania.

EN

In the present study the role of strain rate in metal forming processes, results of experimental tests and modelling computation have been performed on microalloyed steel with Nb. Compression tests using Schenck pulsator and SHPB with different deformation history were carried out. As a results of experimental tests flow curves were obtained. Modified Zerilli-Armstrong model was used to obtain modelling computation of flow stress. It was showed that established flow stress model has a good compatibility with experimental data and depends on deformation temperature and strain rate.

14

Wpływ odkształcenia plastycznego na przemiany austenitu przechłodzonego stali mikrostopowej

75%

Opiela M. , Wojtacha A.

Stal, Metale & Nowe Technologie

|

2019

|

tom nr 1-2

74--80

PL

W pracy przedstawiono wyniki badań wpływu odkształcenia plastycznego oraz szybkości chłodzenia na strukturę i postać krzywych przemian fazowych austenitu przechłodzonego stali mikrostopowej z Nb, Ti, V i B. Wyznaczono krzywe przemian austenitu przechłodzonego nieodkształconego plastycznie (CTPc) oraz odkształconego plastycznie (OCTPc).

EN

The aim of the paper is to investigate the influence of plastic deformation and cooling rate on the structure and shape of the supercooled austenite transformations diagrams of a Nb-Ti-V-B microalloyed steel. The CCT diagrams of underformed and plastically deformed supercooled austenite were developed. The plastic deformation of steel prior to the start of phase transformations results in a sharp acceleration of pearlitic transformation and a slight translation of bainitic transformation towards shorter times. The elaborated curves of supercooled austenite transformations of the steel create possibilities to develop an industrial technology for thermomechanically treated forgings of high mechanical properties.

15

Ciągliwość mikroskopowej stali konstrukcyjnej do regulowanej obróbki cieplno-plastycznej

75%

Maguda T. M. , Pytel S. M.

Zeszyty Naukowe Politechniki Świętokrzyskiej. Mechanika

|

2003

|

tom Z. 78

305-314

PL

W pracy przedstawiono wyniki badania mikrostruktury oraz odporności na pękanie mikroskopowej stali konstrukcyjnej gatunku 12HGMNb poddawanej regulowanemu kuciu w zakresie rekrystalizacji austenitu i bezpośrednim chłodzeniu w czterech różnych ośrodkach chłodzących. Otrzymane wyniki porównano z pomiarami odpornośsci na pękanie trzech gatunków stali 30G2, 40HM oraz 45G2V stosowanych na odkuwki ulepszane cieplnie.

EN

A new low-carbon, microalloyed steel has been developed for forging applications. This steel is to be used in the forged and direct quenched condition without further heat treatment. In this condition the steel exhibits a bainite-martensite microstructure which is both strong and very tough. The results indicated that this new steel can easily replace other high strength steels normally considered for high strength forgings, e.g. medium-carbon microalloyed steels and conventional quenched and tempered steels (QT). It has been shown that the fracture toughness and the impact toughness properties of the microalloyed, multiphase steel are the same or better than those of medium-carbon microalloyed or conventional QT steels for the similar level of strength. The unique properties exhibited by this new steel offers a real opportunity for cost savings in the forging of conventional components.

16

Microtexture development during the alpha -> gamma phase transformation in steel.

75%

Bruckner G. , Pospiech J. , Seidl I. , Gottstein G.

Inżynieria Materiałowa

|

1998

|

tom R. XIX, nr 3

204-208

EN

In a microalloyed low carbon steel diffusion controlled alpha -> gamma phase transformation was investigated by use of EBSD. Orientation Microscopy was performed on a marked spot both in the ferritic and after transformation in the austenitic state. Through an appropriate process the austenitic state was preserved even at room temperature. In the phase transformation the Kurdjumov - Sachs (K-S) relation dominates.

17

Strain-induced austenitic structure in microalloyed steels

75%

Dziedzic D. , Muszka K. , Majta J.

Archives of Metallurgy and Materials

|

2013

|

tom Vol. 58, iss. 3

745--750

EN

Austenite morphology is one of the main factors determining austenite-ferrite transformation kinetic and effectively affects the final microstructure and properties. The basic criteria for proper assessment of the austenite transformation products, theirs refinement, is the relation between the nucleation to growth rates. The main factor accelerating both, the nucleation rate of austenite during heating, and ferrite during cooling is the presence of accumulated deformation energy. The primary aim of this work is to increase our knowledge of the effects of deformation - its accumulated energy on the austenite structure and properties. Two specific steel grades were selected for the present investigation, i.e. microalloyed and IF steel, essentially different in equilibrium transformation temperatures. Obtained austenitic microstructures were analyzed, first of all as a start point for the austenite-to-ferrite transformation. Specific case of this transformation was considered i.e. Strain Induced Dynamic Transformation SIDT. The characteristic feature of the SIDT is the strong dependence of theirs kinetic on the austenite morphology, especially grain size. Thermomechanical processing, that utilize the SIDT, is one of the most effective ways to produce ultrafine-grained steel. One of the main benefits of the austenite refinement, just before the γ→α transformation, is its significant effect on the microstructure evolution during subsequent thermomechanical processing. Experimental results clearly show how direct and positive influence the austenite grain refinement has on the composition and refinement of transformation products. Presented study was focused on Strain Induced Dynamic Reverse Transformation. It is proved that this kind of transformation is very efficient way to intensify thermomechanical processing of microalloyed steels. Dynamic transformation kinetics were analyzed based upon flow curves recorded during the SIDT process. The main effect of presented research is analyze of influence of prior microstructure on dynamically formed austenite morphology.

PL

Morfologia struktury austenitycznej jest jednym z podstawowych czynników rzutujących na przebieg przemiany austenit-ferryt, a co za tym idzie na własności końcowe struktury ferrytycznej. Podstawowym kryterium oceny przemiany austenitu pod kątem stopnia rozdrobnienia powstających produktów jego przemiany jest stosunek prędkości zarodkowania nowej fazy do prędkości jej wzrostu. Kluczowym czynnikiem przyspieszającym zarodkowanie zarówno fazy austenitycznej przy nagrzewaniu oraz ferrytu przy chłodzeniu jest obecność zakumulowanej energii odkształcenia. Podstawowym celem prezentowanych badań była ocena wpływu odkształcenia oraz wynikającej z niego energii zmagazynowanej na właściwości struktury austenitycznej. Badania wykonano z wykorzystaniem dwóch charakterystycznych gatunków stali - mikrostopowej i typu IF, istotnie różniących się równowagowymi temperaturami przemian. Otrzymana struktura austenityczna była badana przede wszystkim pod kątem wpływu jej morfologii na kinetykę i produkty przemiany austenit-ferryt. Rozważany był szczególny przypadek tej przemiany - Indukowana Odkształceniem Przemiana Dynamiczna (ang. Strain Induced Dynamic Transformation SIDT). Cecha charakterystyczna SIDT jest silna zależność jej kinetyki od morfologii austenitu. Zastosowanie przeróbki termomechanicznej z wykorzystaniem SIDT jest bardzo efektywnym sposobem wytwarzania stali ultra drobnoziarnistych. Podstawowym kryterium oceny jakościowej struktury austenitycznej jest jej stan przed przemianą, co bezpośrednio kształtuje skład mikrostruktury w wyrobie gotowym oraz stopień jej rozdrobnienia. W prezentowanej pracy skupiono się na indukowanej odkształceniem przemianie odwrotnej. Stwierdzono, że ta droga mozna zintensyfikowac procesy mikrostrukturalne wykorzystywane w przeróbce termomechanicznej stali mikrostopowych. Kinetykę przemian dynamicznych oceniano na podstawie analiz krzywych płynięcia zarejestrowanych podczas odkształcania w warunkach sprzyjających intensyfikacji przemian fazowych. Efektem głównym wykonanych badań jest analiza wpływu mikrostruktury wyjściowej na morfologię austenitu powstałego w wyniku przemiany dynamicznej.

18

Shear deformation and failure of explosive welded Inconel-microalloyed steels bimetals

63%

Kwiecień M. , Majta J. , Dziedzic D.

Archives of Civil and Mechanical Engineering

|

2014

|

tom Vol. 14, no. 1

32--39

EN

In the following study, the forced shear specimens were investigated to obtain mechanical characterization of Inconel-microalloyed steels bimetals achieved through explosive bonding process. The chrome–molybdenum steel (16Mo3) and high strength microalloyed steel (X70) plates were joined and compared as base materials in the bimetals. Tests were performed quasi-statically and dynamically to examine the influence of strain rate on the shear strength of the metallurgical bond between two steel components. The joined area was also analyzed using microhardness measurements and by light microscopy. (Wave bonding interface and plastic deformation was present in both bimetals). Melted zones, especially In the case of 16Mo3 steel, were observed. The qualitative and quantitative assessments of the mechanical state-using computer simulations as well as microhardness distributions and microstructure development in the forced shear specimens showed that bimetal Inconel 601/X70 was superior to Inconel 601/16Mo3.

19

Wytwarzanie elementów kutych ze stali mikrostopowych metodą obróbki cieplno-mechanicznej

63%

Adamczyk J. , Opiela M. , Grajcar A.

Inżynieria Materiałowa

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2003

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tom R. XXIV, nr 6

825-828

PL

W pracy zbadano wpływ obróbki cieplno-mechanicznej na strukturę i własności mechaniczne elementów kutych ze stali konstrukcyjnych C-Mn z mikrododatkami Ti, V, B i N. Warunki obróbki cieplno-mechanicznej opracowano na podstawie składu chemicznego badanych stali, kinetyki rozpuszczania się w austenicie faz międzywęzłowych TiN, VN, BN i AlN oraz wpływu temperatury austenityzowania i czasu wytrzymania izotermicznego próbek w temperaturze końca odkształcenia plastycznego na wielkość ziaren austenitu pierwotnego. Zastosowanie energooszczędnej metody obróbki cieplno-mechanicznej pozwala na uzyskanie drobnoziarnistej struktury austenitu po wytrzymaniu izotermicznym wyrobów w temperaturze końca odkształcenia plastycznego przez określony czas przed hartowaniem w wodzie oraz wytwarzanie wyrobów kutych uzyskujących po wysokim odpuszczaniu granicę plastyczności Rp0,2>690 MPa, wytrzymałość Rm>770 MPa, twardość 220 do 230 HB i energię łamania KV20 stopni Celsjusza>180J.

EN

Influence of the thermo-mechanical treatment on structure and mechanical properties of constructional C-Mn steels with Ti, V, B and N microadditions forged products, was investigated in this paper. The thermo-mechanical treatment conditions on the basis of: the chemical composition of investigated steels, a solubility kinetics of TiN, VN, BN, and AlN in the austenite, the influence of the austenitizing temperature and a isothermal holding time in the finish plastic deformation temperature on the austenite grain size were established. Energy-saving thermo-mechanical process enables to obtain the finegrained austenite structure after a isothermal holding of products at the finish plastic deformation temperature before quenching. Forged products of applying this process and tempering obtain the yield stress Rp0,2>690 MPa, UTS (Rm)>770 MPa, hardness 220/230 HB and breaking energy KV20 stopni Celsjusza>180J.

20

Technologie i urządzenia stosowane do obróbki cieplnej odkuwek matrycowych bezpośrednio po kuciu

63%

Skubisz P.

Stal, Metale & Nowe Technologie

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2015

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tom nr 9-10

66--70

PL

Artykuł opisuje dotychczasowe osiągnięcia z zakresu technologii wytwarzania odkuwek matrycowych o wysokiej wytrzymałości i ciągliwości oraz stosowanych lub przewidywanych do zastosowania gatunków stali. W artykule dokonano klasyfikacji technologii kontrolowanej obróbki cieplno-plastycznej stosowanej przemysłowo oraz przeglądu urządzeń do kontrolowanego chłodzenia odkuwek matrycowych.

EN

Current achievements in the field of manufacturing technologies for high-strength and good ductility closed-die forged products are discussed, with reference to the commonly used and emerging steel grades. The review and classification of the controlled thermomechanical treatment technologies applied in industrial practice are presented, with a focus on control cooling devices encountered in the domestic forging industry.