DCCT Diagrams of X70 Pipeline Grade Influenced by Preheating Conditions

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61989100%3A27360%2F17%3A10238595" target="_blank" >RIV/61989100:27360/17:10238595 - 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

DCCT Diagrams of X70 Pipeline Grade Influenced by Preheating Conditions

Popis výsledku v původním jazyce

Heavy seamless tubes are produced by the Big Mannesmann Rolling Mill in Třinecké železárny plant. Their final microstructures and properties are not only given by steel chemistry, they are also largely influenced by cooling conditions after finish-rolling. Continuous cooling transformation (CCT) analysis of various steel grades has been increasingly an object of the researchers&apos; attention. Nevertheless, the phase transformations are also affected by the initial microstructure (e.g. austenite grain size) and previous deformation (ratio of residual hardening and softening). For that reason the DCCT diagrams (including the influence of defined deformation e = 0.35) of the HSLA steel X70 were designed for two states of the initial microstructures. In rough outline, the tested steel has the following chemical composition: 0.16 C-1.0 Mn-0.2 Cr-0.05 V-0.03 Nb (in wt. %). Phase transformations in the course of cooling were studied by dilatometer tests (performed in the Gleeble 3800 hot deformation simulator, to wide cooling rates range, from 0.15°C/s to 80 °C/s), metallographic analysis and hardness as well as micro-hardness measurement. Coarse gamma grains (G = 3) were produced by high-temperature preheating (1280 °C) of the dilatometer samples made from the continuously cast bloom with diameter of 400 mm. Fine initial microstructure (G = 11) was obtained by severe laboratory hot rolling of the cast material and normalizing. Lower temperature of austenitization (900 °C) has been set in the dilatometer to make such samples from the normalized material. Great differences were observed, some coarse-grain samples containing acicular ferrite, whereas mixture of martensite and austenite appeared in the fine-grain samples cooled with rates of at least 12 °C/s. Lower heating temperature substantially accelerated the gamma/alpha transformation at high cooling rates.

Název v anglickém jazyce

DCCT Diagrams of X70 Pipeline Grade Influenced by Preheating Conditions

Popis výsledku anglicky

Heavy seamless tubes are produced by the Big Mannesmann Rolling Mill in Třinecké železárny plant. Their final microstructures and properties are not only given by steel chemistry, they are also largely influenced by cooling conditions after finish-rolling. Continuous cooling transformation (CCT) analysis of various steel grades has been increasingly an object of the researchers&apos; attention. Nevertheless, the phase transformations are also affected by the initial microstructure (e.g. austenite grain size) and previous deformation (ratio of residual hardening and softening). For that reason the DCCT diagrams (including the influence of defined deformation e = 0.35) of the HSLA steel X70 were designed for two states of the initial microstructures. In rough outline, the tested steel has the following chemical composition: 0.16 C-1.0 Mn-0.2 Cr-0.05 V-0.03 Nb (in wt. %). Phase transformations in the course of cooling were studied by dilatometer tests (performed in the Gleeble 3800 hot deformation simulator, to wide cooling rates range, from 0.15°C/s to 80 °C/s), metallographic analysis and hardness as well as micro-hardness measurement. Coarse gamma grains (G = 3) were produced by high-temperature preheating (1280 °C) of the dilatometer samples made from the continuously cast bloom with diameter of 400 mm. Fine initial microstructure (G = 11) was obtained by severe laboratory hot rolling of the cast material and normalizing. Lower temperature of austenitization (900 °C) has been set in the dilatometer to make such samples from the normalized material. Great differences were observed, some coarse-grain samples containing acicular ferrite, whereas mixture of martensite and austenite appeared in the fine-grain samples cooled with rates of at least 12 °C/s. Lower heating temperature substantially accelerated the gamma/alpha transformation at high cooling rates.

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

8

Strana od-do

375-382

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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