Heat-treated steel material, method for producing same, and base steel material for same

A manufacturing method and steel technology, applied in heat treatment furnaces, heat treatment equipment, manufacturing tools, etc., can solve problems such as wrinkles and springback, and achieve the effect of reducing costs

CN102859020AActive Publication Date: 2013-01-02NIPPON STEEL CORP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Publication Date
2013-01-02

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Abstract

Disclosed is a steel material which can be sufficiently quenched by short time heating at low temperatures and is capable of providing a high strength molded article. The steel material is suitable as a material for hot pressing or hot three-dimensional bending. Specifically, the steel material has a chemical composition that contains, in mass%, 0.05-0.35% of C, 0.5% or less of Si, 0.5-2.5% of Mn, 0.03% or less of P, 0.01% or less of S, 0.1% or less of sol. Al, 0.01% or less of N, and if necessary, one or more elements selected from the group consisting of 0.0001-0.005% of B, 0.01-0.1% of Ti, 0.18-0.5% of Cr, 0.03-0.1% of Nb, 0.18-1.0% of Ni and 0.03-0.5% of Mo, and has a steel structure wherein the spheroidization ratio of carbides is 0.60-0.90.
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Description

technical field

[0001] The present invention relates to a steel material for heat treatment, a heat-treated steel material obtained by heat-treating the steel material, and a method for manufacturing the heat-treated steel material. The steel material of the present invention is suitable for applications where quenching is performed after heating for a short time, and is particularly suitable as a raw material for so-called hot three-dimensional bending and hot pressing. In addition, even if the heat-treated steel material of the present invention is obtained by heat treatment of quenching after heating for a short time, it has high strength, good fatigue resistance and toughness in the same way. Background technique

[0002] In recent years, from the viewpoint of global environmental problems and crash safety performance, reduction in thickness and increase in strength of structural parts for automobiles have been demanded.

[0003] In response to these demands, automotive...

Examples

Embodiment 1

[0115] The continuous casting castings A~I with the chemical composition shown in Table 1 are put into the heating furnace for heating, taken out from the heating furnace, hot rolling is started at 1150°C, hot rolling is terminated at 870°C, and hot rolling is started at 20~1000°C / sec Cool at an average cooling rate, and coil at 450 to 600°C to form a hot-rolled steel sheet with a thickness of 3.6 mm. The hot-rolled steel sheet thus obtained was descaled by pickling. The steel sheet obtained in this way is called "hot-rolled material".

[0116] A part of the descaled hot-rolled steel sheet was cold-rolled at a cold-rolling rate of 50% to form a cold-rolled steel sheet. The steel sheets are called "high hardness cold-rolled sheets (full hard materials)".

[0117] A part of the obtained cold-rolled steel sheets were kept in a heating furnace at 650° C. for 20 hours, and then air-cooled to room temperature. This steel plate is called "heating furnace material".

[0118] In ad...