Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
1579523 | Materials Science and Engineering: A | 2010 | 7 Pages |
Abstract
An ultra-low carbon niobium-microalloyed steel with yield strength of â¼900 MPa has been processed on a pilot-plant scale. The microstructure of the steel is primarily characterized by lower bainite and acicular ferrite, with small fraction of lath-martensite and martensite-austenite (MA) constituents. Bainite is present as fine domains. A combination of niobium and titanium precipitates was observed at the grain boundaries and in the interior of the grains and includes irregular (â¼40-150 nm of (Nb, Ti)(C, N)) and fine cuboidal/spherical particles of NbC (â¼30-50 nm). It was observed that accelerated cooling inhibited the precipitation of Nb and Ti carbides. The Charpy impact toughness at â20 °C was 200 J and tensile elongation was 15% with the yield ratio of less than 0.84. The good matching of high strength and low yield ratio was realized by two-stage thermo-mechanical rolling combined with fast cooling.
Related Topics
Physical Sciences and Engineering
Materials Science
Materials Science (General)
Authors
Aimin Guo, R.D.K. Misra, Jinqiao Xu, Bin Guo, S.G. Jansto,