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

Result code in 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>

Result on the web

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DOI - Digital Object Identifier

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Result language

angličtina

Original language name

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

Original language description

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.

Czech name

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Czech description

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Type

D - Article in proceedings

CEP classification

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OECD FORD branch

20501 - Materials engineering

Project

<a href="/en/project/LO1203" target="_blank" >LO1203: Regional Materials Science and Technology Centre - Feasibility Program</a><br>

Continuities

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

Publication year

2017

Confidentiality

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

Article name in the collection

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

Number of pages

7

Pages from-to

299-305

Publisher name

Tanger

Place of publication

Ostrava

Event location

Brno

Event date

May 24, 2017

Type of event by nationality

WRD - Celosvětová akce

UT code for WoS article

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