Ultrafine crystal bainite high-strength steel and manufacturing method thereof

Abstract

The invention relates to ultrafine crystal bainite high-strength steel and a manufacturing method thereof. The ultrafine crystal bainite high strength steel comprises the components by mass percent: 0.03-0.06% of C, 0.05-0.90% of Si, 1.00-2.00% of Mn, 0.05-0.25% of Cr, 0.03-0.08% of Nb, 0.02-0.04% of Al, 0.004-0.020% of Ti, 0.0010-0.0020% of B, 0.01-0.03% of Zr as well as balance of Fe and inevitable impurities, and P cm is<=0.20%. 13.14C+14.21Nb+6.32Cr+680B-1.98Mn<(Si)<12.22C+9.87Nb+8.11Cr+1210B-1.25Mn. By adopting control thermal mechanical rolling and accelerated cooling technology, the invention can obtain an ultrafine bainite ferrite lath and structure with mahaud components distributed along the interface of the lath; and the yield strength is more than 690MPa, the tensile strength is more than 780MPa, and the Charpy impact power Akv (-20 DEG C) is>=120J. A steel plate has good welding performance, is welded at the room temperature and has no welding cold crack after being placed for 48h.

Description

A kind of ultra-fine-grained bainitic high-strength steel and its manufacturing method technical field The invention relates to high-strength structural steel, in particular to an ultra-fine-grained bainite high-strength steel and a manufacturing method thereof. Background technique Controlled rolling technology has developed rapidly in recent years and has become popular all over the world. This period has many technical characteristics. ①Application of rolling technology, developed a system that can be applied to all rolling mills; ②Consciously applied rolling in the two-phase region to improve performance; ③Using the recrystallization of austenite fine grains in the middle temperature region, proposed the theory of recrystallization controlled rolling (Recrystallization Controlled Rolling RCR ); ④Utilization of Ti, Nb, and V composites, Ti can inhibit austenite recrystallization, form TiN to inhibit grain growth and control the shape of sulfidic inclusions; ⑤The applic...

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Problems solved by technology

It was found in the factory production that the strength of the finishing rolling temperature decreased and the strength also decreased, which may be due to the decrease of the hardenability of deformed austenite at low temperature; ⑧Development of cooling equipment

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