Thin steel plate and manufacturing method thereof
A manufacturing method and technology of thin steel plates, applied in the direction of manufacturing tools, resistance welding equipment, metal material coating technology, etc., can solve problems such as cracking and inability to apply automotive parts, and achieve high strength and excellent weldability
Active Publication Date: 2021-08-24
JFE STEEL CORP
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Problems solved by technology
Steel sheets that do not satisfy weldability cannot be used for automotive parts due to defects such as cracks when joining automotive components by welding
Method used
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Embodiment
[0122] A steel raw material with a wall thickness of 250 mm having the composition shown in Table 1 was subjected to a hot rolling process under the hot rolling conditions shown in Table 2 to produce a hot-rolled sheet, and the cold rolling rate was 29% to 68%. The following cold rolling process was used to produce cold-rolled sheets, and annealing under the conditions shown in Table 2 was performed in a continuous annealing line or a continuous hot-dipping line. Then, plating treatment is performed, and alloying treatment is performed as necessary. Here, the temperature of the coating bath (coating composition: Zn-0.13 mass% Al) dipped in the continuous hot-dip production line is 460°C, and the coating deposition amount is set to GI material (hot-dip steel plate), GA material (alloyed hot-dip steel plate) are 45~65g / m per single side 2 In this case, the amount of Fe contained in the plating layer of the GA material was set within a range of 6 to 14% by mass.
[0123] The Ms...
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Abstract
The present invention provides a thin steel plate having a tensile strength of 900 MPa or more and good weldability, and a method for producing the same. A thin steel plate characterized by having a specific composition, and containing 30% or less (including 0%) of ferrite in terms of area ratio, and 70% or more (including 100%) of ferrite in area ratio. Structures other than ferrite and tempered martensite as the remaining structure in which the total area ratio of fire martensite is 10% or less (including 0%), and the average grain size of tempered martensite is 5 μm or less The average grain size of iron-based carbides precipitated on the grain boundaries of tempered martensite is 100 nm or less, and the total of Si and Mn on the grain boundaries of tempered martensite is 5 atomic % or more in terms of atomic concentration Steel structure, the tensile strength is above 900MPa.
Description
technical field [0001] The present invention relates to thin steel sheets and methods for their manufacture. Background technique [0002] In recent years, from the viewpoint of protecting the global environment, CO 2 For the purpose of emission limits, the entire automotive industry aims to improve the fuel efficiency of vehicles. In improving the fuel efficiency of automobiles, it is most effective to reduce the weight of automobiles by reducing the thickness of used parts. Therefore, in recent years, high-strength steel sheets (thin steel sheets after high strength) are used as raw materials for automobile parts usage continues to increase. [0003] On the other hand, the weldability of steel sheets tends to deteriorate as the strength increases. Therefore, a steel plate having excellent weldability in addition to high strength is desired. A steel sheet that does not satisfy weldability cannot be applied to automobile parts or the like due to defects such as cracks wh...
Claims
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IPC IPC(8): C22C38/00C21D9/46C22C18/00C22C38/06C22C38/60C23C2/06C23C2/28
CPCC23C2/06C23C2/28C21D9/46C22C18/00C22C38/06B23K11/11C21D6/001C21D6/002C21D6/004C21D6/005C21D6/008C21D6/02C21D8/0205C21D8/0226C21D8/0236C21D8/0263C22C38/001C22C38/002C22C38/005C22C38/008C22C38/02C22C38/04C22C38/08C22C38/12C22C38/14C22C38/22C22C38/28C22C38/38C22C38/44C22C38/46C22C38/48C22C38/50C22C38/54C22C38/58C21D2211/005C21D2211/008C23C2/02C23C2/40B23K31/12B23K11/16B23K2103/04C23C2/0224C22C38/60C23C2/29C21D2211/004C21D8/0405C21D8/0426C21D8/0436C21D8/0463C22C38/34C22C38/36
Inventor 高坂典晃中垣内达也
Owner JFE STEEL CORP