High-tensile-strength hot-rolled steel sheet and method for producing same
A hot-rolled steel plate, high-tension technology, applied in the direction of manufacturing tools, chemical instruments and methods, heat treatment furnaces, etc., can solve problems such as distortion of parts, and achieve the effect of good workability and excellent material stability
Active Publication Date: 2014-07-09
JFE STEEL CORP
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Problems solved by technology
In addition, if steel plates with different local strengths are press-formed, the amount of springback will change in proportion to the strength, and the parts will be distorted.
Method used
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[0102] Molten steel having the composition shown in Table 1 was smelted and continuously cast by a generally known method to produce a billet (steel material) with a wall thickness of 250 mm. After heating these billets to 1250°C, rough rolling and finish rolling were carried out, and after finishing rolling, cooling and coiling were performed to produce hot-rolled steel sheets with a thickness of 2.3 mm and a width of 1400 mm (the hot-rolled numbers in Table 2: 1~24). Table 2 shows the finish rolling temperature, the average cooling rate of cooling (the average cooling rate from the finish rolling temperature to the coiling temperature) and the coiling temperature of the above-mentioned finish rolling.
[0103] Next, a part of the hot-rolled steel sheets (hot-rolled numbers in Table 2: 3, 5, and 15) obtained as above were pickled to remove surface scale, and then annealed (annealing temperature: 680° C., Holding time: 120 seconds), dipped in a hot-dip galvanizing bath (bath ...
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Abstract
Provided is a hot-rolled steel sheet having: a composition containing, by mass%, over 0.05% and no greater than 0.13% of C, no greater than 0.3% of Si, 0.5-2.0% inclusive of Mn, no greater than 0.025% of P, no greater than 0.005% of S, no greater than 0.0060% of N, no greater than 0.1% of Al, 0.07-0.18% inclusive of Ti, and over 0.13% and no greater than 0.30% of V, such that Ti and V satisfy 0.25 < Ti + V <= 0.45 (Ti and V being the amount contained (mass%) of the respective elements), having at least 0.05% and less than 0.15% of solid-solution V, and the remainder comprising Fe and unavoidable impurities; a matrix having an area ratio of ferrite phase that is at least 95% of the overall structure; and a structure such that minute carbides containing Ti and V and having an average grain size of less than 10 nm are dispersed / precipitated, the volume ratio of the minute carbides with respect to the overall structure is at least 0.0050, and the number fraction of carbides containing Ti and having a grain size of at least 30 nm as a share of the total number of carbides is less than 10%. Further provided is a method for producing the hot-rolled steel sheet.
Description
technical field [0001] The present invention relates to a tensile strength suitable for raw materials of transportation equipment parts such as automobile parts, structural parts, etc., having excellent processability, especially excellent stretch flangeability and bending properties, and excellent material stability (TS): High-tensile hot-rolled steel sheet of 980 MPa or more and its manufacturing method. Background technique [0002] From the viewpoint of global environmental protection, in order to reduce CO 2 In terms of emissions, it is necessary to reduce the weight of the car body while maintaining the strength of the car body, thereby improving the fuel efficiency of the car, which has become a very important issue in the automotive industry. In order to reduce the weight of an automobile body while maintaining its strength, it is effective to increase the strength of a steel sheet used as a raw material for automobile parts to reduce the thickness of the steel shee...
Claims
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Login to View More IPC IPC(8): C22C38/00C21D9/46C22C18/04C22C38/14C22C38/60C23C2/06
CPCC23C2/02C23C2/06C21D9/46C22C18/04C22C38/14C22C38/60B32B15/013C22C38/001C22C38/02C22C38/04C22C38/06C22C38/12C21D8/0426C21D8/0463C21D8/0478C21D2211/004C21D2211/005C22C38/002C22C38/008C22C38/08C22C38/10C22C38/16C22C38/24C22C38/26C22C38/28C23C2/024C23C2/0224C21D8/0263
Inventor 有贺珠子船川义正内田康信
Owner JFE STEEL CORP