High strength hot-rolled steel sheet and method for producing same
A technology of hot-rolled steel sheets and manufacturing methods, applied in the direction of manufacturing tools, metal rolling, heat treatment furnaces, etc., which can solve the problems of reduced processability and achieve the effect of excellent welded joint characteristics
Active Publication Date: 2014-09-10
JFE STEEL CORP
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- Abstract
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- Claims
- Application Information
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Problems solved by technology
In particular, the application of high-strength hot-rolled steel sheets having a TS of 780 MPa or more is expected, but in general, when the strength of a steel sheet is increased, properties such as workability decrease
Method used
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Embodiment
[0072] Steel Nos. A to J having the component compositions shown in Table 1 were melted in a converter, and steel slabs were produced by continuous casting. From these slabs, hot-rolled steel sheets Nos. 1 to 16 were produced under the hot-rolling conditions shown in Table 2. In addition, cooling was started within 2.0 seconds in either case after hot rolling.
[0073] Then, a test piece for structure observation was cut out from the obtained steel plate, and the Ti at the position of 1 / 8 to 3 / 8 of the plate thickness was obtained by the above-mentioned method.* amount and the area ratio of the bainite phase.
[0074] In addition, a JIS No. 5 tensile test piece (direction perpendicular to the rolling direction) was cut out, and a tensile test was performed based on JIS Z2241 to measure yield strength YS, TS, and total elongation El.
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Abstract
A high-strength hot-rolled steel sheet containing by mass 0.05-0.12% C, 0.05-1.0% Si, 0.5-1.8% Mn, at most 0.04% P, at most 0.0030% S, 0.005-0.07% Al, at most 0.006% N, and 0.05-0.15% Ti, the remainder having a component composition comprising Fe and unavoidable impurities, the amount (Ti*) of the Ti content [Ti] present as a precipitate in a position from 1 / 8 to 3 / 8 of the sheet thickness being from 0.3[Ti] to 0.6[Ti]; and having a microstructure in which an area ratio accounting for the entire structure of a bainite phase exceeds 95%.
Description
technical field [0001] The present invention relates to a high-strength hot-rolled steel sheet suitable for structural parts such as running parts and frames of automobiles, and more particularly to a high-strength hot-rolled steel sheet having a tensile strength TS of 780 MPa or more and excellent welded joint properties and a manufacturing method thereof. Background technique [0002] In recent years, from the standpoint of protecting the global environment, the improvement of fuel efficiency by reducing the weight of automobiles has become a global issue. In order to reduce the weight of automobiles, in addition to changing the shape of structural components such as running parts and frames, it is also necessary to increase the strength of steel plates used in structural components. In particular, applications to high-strength hot-rolled steel sheets having a TS of 780 MPa or more are expected, but in general, when the strength of a steel sheet is increased, characteristi...
Claims
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IPC IPC(8): C22C38/00B21B3/00C21D8/02C21D9/46C22C38/14C22C38/58
CPCC21D8/0263C21D8/02C22C38/14C22C38/04C22C38/58C21D9/46C21D8/0205C22C38/001C22C38/002C21D2211/004C22C38/02C21D8/0226C22C38/12C22C38/28C22C38/005C22C38/00C22C38/06B21B3/00C22C38/08C22C38/16C21D2211/002
Inventor 中岛胜己斋藤勇人船川义正
Owner JFE STEEL CORP