ISSN:
1662-9752
Source:
Scientific.Net: Materials Science & Technology / Trans Tech Publications Archiv 1984-2008
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
New conceptual TMCP process for manufacturing high strength steel plates, which isapplied an on-line heat treatment immediately after accelerated cooling (ACC), was developed.Transformation and precipitation behavior in the new TMCP process was investigated andcompared with those in conventional ACC process and quenching and tempering process (Q+T).In the ACC process and Q+T process, microstructures were consisted of bainitic ferrite andsecond phase, such as cementite or martensite-austenite constituent (MA). And fine carbides, whichwere formed randomly, were observed in Q+T steel. On the other hand, in the new TMCP processpolygonal ferrite was observed in addition to bainitic ferrite and cementite, and two kinds ofprecipitation forms, random precipitation and row precipitation, were observed. It was found thatferrite transformation is promoted during heating after accelerated cooling, which brings rowprecipitation of fine carbides.Furthermore, Control of the formation of MA this new TMCP process. In the conventionalACC process, MA constituents are formed from carbon enriched untransformed austenite during aircooling after ACC, and formation of MA is hard to prevent for higher strength steels. On the otherhand, carbon enrichment to untransformed austenite can be prevented by carbide formation duringon-line heat treatment after ACC. It was demonstrated that homogeneous microstructure with verylow amount of MA constituents was achieved by the new TMCP process. And, absence of brittlephase brought excellent resistance to hydrogen induced cracking in NACE sour environment.In this paper, details of the metallurgical and mechanical feature of this new TMCP steel werediscussed, and application to sour resistant linepipe steel was introduced
Type of Medium:
Electronic Resource
URL:
http://www.tib-hannover.de/fulltexts/2011/0528/02/15/transtech_doi~10.4028%252Fwww.scientific.net%252FMSF.539-543.4732.pdf
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