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Hot-stamp-molded article, process for production of steel sheet for hot stamping, and process for production of hot-stamp-molded article

A manufacturing method, hot embossing technology, applied in the direction of manufacturing tools, chemical instruments and methods, metal rolling, etc., can solve the problems of insufficient control of structure, high aspect ratio, and inability to fully ensure strength and toughness, and achieve absorption Excellent energy properties, improved balance of strength and toughness, and improved energy absorption properties

Active Publication Date: 2013-02-20
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, in this patent document 4, the aspect ratio of prior-austenite grain size before hot stamping is very high, so after hot stamping, the structure cannot be sufficiently controlled, and there is a possibility that a sufficient balance between strength and toughness cannot be ensured.

Method used

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  • Hot-stamp-molded article, process for production of steel sheet for hot stamping, and process for production of hot-stamp-molded article
  • Hot-stamp-molded article, process for production of steel sheet for hot stamping, and process for production of hot-stamp-molded article
  • Hot-stamp-molded article, process for production of steel sheet for hot stamping, and process for production of hot-stamp-molded article

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0090] The steels (Steel A~Steel Y) with the composition shown in Table 2 were tapped from the converter, cast into slabs, and rolled under given hot rolling conditions (heating temperature: 1220°C, finish rolling temperature: 870°C, The total reduction applied by the first two stands of the stand: 65%, the time from the end of finish rolling to the start of cooling: 0.5 seconds, and the coiling temperature: 600°C) are hot-rolled to produce a hot-rolled plate with a thickness of 3 mm. steel plate. In Steels A~L and Steels U~Y, the grain size of prior austenite in the hot-rolled steel sheet is 6 μm or less, and the size ratio of the length of prior austenite in the rolling direction to the length in the thickness direction is 1.3 above. The hot-rolled steel sheet was cold-rolled to obtain a cold-rolled steel sheet with a thickness of 1.4 mm, and then continuously annealed under the conditions shown in Table 3, and a plating treatment was performed after the annealing if necess...

Embodiment 2

[0094] For I, U and Y steels in Table 2, with given hot rolling conditions (heating temperature: 1250°C, finish rolling temperature: 880°C, total reduction applied from the first two stands of the last stand: 60 %, the time from the end of finish rolling to the start of cooling: 0.8 seconds, coiling temperature: 550°C) to obtain a hot-rolled steel sheet with a thickness of 2 mm, and then pickle it. These hot-rolled steel sheets are directly heated to 880°C in a heating furnace, and after holding the heat for 120 seconds, they are inserted into a mold with a water supply port for spraying water from the surface and a discharge port for sucking in the water, and spray water through it. Heating-cooling treatment to cool to room temperature. In addition, after pickling, the same heating and cooling treatment was performed on hot-rolled steel sheets subjected to hot-dip galvanizing (GI, GA) or hot-dip aluminizing containing 10% Si. On the other hand, with the given hot rolling con...

Embodiment 3

[0097] Steel I in Table 2 was hot-rolled under the hot-rolling conditions shown in Table 5, and then cold-rolled at a reduction ratio of 50%. These steel plates were heated to 850° C. at the heating rate shown in Table 5, sandwiched in a mold having a water supply port for spraying water from the surface and a water discharge port for sucking in the water, and cooled to room temperature by spraying water. In addition, as a result of examining the cross-sectional structure with an optical microscope, the steel sheet provided with these heat histories contained 98% or more of martensite in terms of area ratio. Moreover, about the obtained steel plate, the material property was evaluated similarly to Example 1, and the obtained result is shown in Table 5. In addition, regarding the toughness, the Charpy test was carried out at -120°C, and the evaluation was performed in conversion to a plate thickness of 10 mm. In this case, 85 J / cm 2 The steel plate with the above energy absorp...

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Abstract

A hot-stamp-molded article comprises, in mass%, 0.20 to 0.35% of C, 0.1 to 0.5% of Si, at least one element selected from Mn and Cr in the total amount of 1 to 3%, 0.005 to 0.06% of Al, 0.002 to 0.1% of Ti, 0.002 to 0.1% of Nb, 0.003 to 0.007% of O, 0.015% or less of P, 0.01% or less of S, 0.004% or less of N, and a remainder made up by Fe and unavoidable impurities, wherein the dimensional ratio of the length of a prior austenite grain in the rolling direction to that in the thicknesswise direction is 1.3 to 2.5 inclusive, the prior austenite grain has an average particle diameter of 6 [mu]m or less, martensite is contained at a proportion of 98% or more, and the tensile strength is 1470 MPa or more.

Description

technical field [0001] The present invention relates to a thermally embossed molded article having an excellent balance between strength and toughness. In particular, the present invention relates to a hot embossed article having a strength of 1470 MPa or more and sufficient energy absorption capacity. In addition, the present invention relates to a method of manufacturing a steel sheet for hot embossing suitable for components manufactured by hot embossing, and a method of manufacturing a hot embossed molded body using the steel sheet for hot embossing. [0002] This application claims priority based on Japanese Patent Application No. 2010-135217 filed in Japan on June 14, 2010 and Japanese Patent Application No. 2011-092811 filed in Japan on April 19, 2011, and the contents thereof are incorporated herein. Background technique [0003] From the viewpoint of global environmental protection, reducing the weight of automobile bodies is an urgent issue. In recent years, studi...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D9/46C22C38/38C22C38/58C23C2/28
CPCB21B1/026C22C38/002C21D7/13C22C38/04C22C38/22B23P17/00C22C38/26C22C38/06C22C38/02B32B15/013C21D8/005C22C38/28C22C38/001C23C26/02C23C24/10B21B45/00C21D9/48C22C38/005B21B45/0203C21D2211/001C21D2211/008C21D8/0226C21D8/0473C22C38/24C22C38/38C21D8/0205C21D8/0263C21D9/46Y10T29/49986Y10T428/12972
Inventor 川崎薰佐野幸一关户义仁
Owner NIPPON STEEL CORP
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