Microstructure Development in the Process of Controled Rolling and Cooling of a Nb-microalloyed Pipe Steel

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27360%2F17%3A10238597" target="_blank" >RIV/61989100:27360/17:10238597 - isvavai.cz</a>

Výsledek na webu

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DOI - Digital Object Identifier

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Jazyk výsledku

angličtina

Název v původním jazyce

Microstructure Development in the Process of Controled Rolling and Cooling of a Nb-microalloyed Pipe Steel

Popis výsledku v původním jazyce

Examination of structure-forming processes of HSLA steel with 0.025 % Nb was performed in relation with rolling of the heavy seamless tubes in the Big Mannesmann mill. Based on the dilatometry data, a DCCT diagram after deformation 0.35 at temperature of 900°C was designed. Hardness HV30 of value 157 was determined for low cooling rate of 0.2°C·s-1 and the structure was consisting mostly of ferrite and pearlite. For faster cooling with rate of 60°C·s-1 the hardness was equal to 404 with entirely martensitic structure. Non-recrystallization temperature was determined by the rolling-cooling-quenching tests and metallography just above 850°C. Finally, steel samples were subjected to temperature controlled rolling and cooling with the rate of 0.25°C·s-1 in the laboratory reversing mill with the working rolls&apos; diameter of 350 mm. Grain refinement as well as homogenization of the final microstructure was observed after lowering the finish rolling temperature in the interval from 990 to 850°C. Greater effect of decreasing finish rolling temperatures was observed below 890°C as a result of deceleration of the recrystallization kinetics due to the precipitation during the cooling phase and getting closer to non-recrystallization temperature. The smallest secondary grain size of 17 μm was achieved despite the initial coarse-grained structure (created by preheating at 1280°C), low degree of material deformation and slow final cooling. Low-temperature finish rolling resulted in a significant increase in the roll forces - approximately by 50 % when comparing the results of experiments performed at temperatures of 990°C and 850°C.

Název v anglickém jazyce

Microstructure Development in the Process of Controled Rolling and Cooling of a Nb-microalloyed Pipe Steel

Popis výsledku anglicky

Examination of structure-forming processes of HSLA steel with 0.025 % Nb was performed in relation with rolling of the heavy seamless tubes in the Big Mannesmann mill. Based on the dilatometry data, a DCCT diagram after deformation 0.35 at temperature of 900°C was designed. Hardness HV30 of value 157 was determined for low cooling rate of 0.2°C·s-1 and the structure was consisting mostly of ferrite and pearlite. For faster cooling with rate of 60°C·s-1 the hardness was equal to 404 with entirely martensitic structure. Non-recrystallization temperature was determined by the rolling-cooling-quenching tests and metallography just above 850°C. Finally, steel samples were subjected to temperature controlled rolling and cooling with the rate of 0.25°C·s-1 in the laboratory reversing mill with the working rolls&apos; diameter of 350 mm. Grain refinement as well as homogenization of the final microstructure was observed after lowering the finish rolling temperature in the interval from 990 to 850°C. Greater effect of decreasing finish rolling temperatures was observed below 890°C as a result of deceleration of the recrystallization kinetics due to the precipitation during the cooling phase and getting closer to non-recrystallization temperature. The smallest secondary grain size of 17 μm was achieved despite the initial coarse-grained structure (created by preheating at 1280°C), low degree of material deformation and slow final cooling. Low-temperature finish rolling resulted in a significant increase in the roll forces - approximately by 50 % when comparing the results of experiments performed at temperatures of 990°C and 850°C.

Druh

D - Stať ve sborníku

CEP obor

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OECD FORD obor

20501 - Materials engineering

Projekt

<a href="/cs/project/LO1203" target="_blank" >LO1203: Regionální materiálově technologické výzkumné centrum - Program udržitelnosti</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>S - Specificky vyzkum na vysokych skolach

Rok uplatnění

2017

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název statě ve sborníku

METAL 2017: conference proceedings : 26th International Conference on Metallurgy and Materials : (reviewed version) : May 24th-26th 2017, Hotel Voroněž I, Brno, Czech Republic, EU

ISBN

978-80-87294-79-6

ISSN

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e-ISSN

neuvedeno

Počet stran výsledku

7

Strana od-do

299-305

Název nakladatele

Tanger

Místo vydání

Ostrava

Místo konání akce

Brno

Datum konání akce

24. 5. 2017

Typ akce podle státní příslušnosti

WRD - Celosvětová akce

Kód UT WoS článku

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