High-strength hot-rolled steel plate and manufacturing method therefor

一种热轧钢板、高强度的技术，应用在制造工具、金属轧制、热处理炉等方向，能够解决韧性断裂等问题

Active Publication Date: 2012-11-21
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] However, it has been difficult to meet these requirements in the past
[0008] In addition, when a car is driven onto a curb, etc., and a strong impact load is applied to the chassis member, ductile fracture may occur starting from the punched surface of the chassis member.

Method used

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  • High-strength hot-rolled steel plate and manufacturing method therefor
  • High-strength hot-rolled steel plate and manufacturing method therefor
  • High-strength hot-rolled steel plate and manufacturing method therefor

Examples

Experimental program
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Effect test

no. 1 Embodiment approach

[0278] Next, reasons for limiting the composition of the high-strength hot-rolled steel sheet according to the first embodiment of the present invention will be described. In addition, below, the mass % in a composition is abbreviated as %.

[0279] C: 0.02%~0.1%

[0280] C is an element that combines with Nb, Ti, etc., and contributes to an increase in tensile strength by precipitation strengthening. In addition, C lowers the cross-sectional shape transition temperature by miniaturizing the microstructure. In addition, C also has the effect of suppressing the peeling of the grain boundary during punching by segregating to the grain boundary in the form of solid solution C, thereby suppressing the occurrence of peeling. When the C content is less than 0.02%, these effects cannot be sufficiently obtained, and desired hole expandability and fracture properties cannot be obtained. On the other hand, when the C content exceeds 0.1%, iron carbide (Fe carbide) which is unfavorabl...

no. 2 Embodiment approach

[0360] Next, a second embodiment of the present invention will be described. The high-strength hot-rolled steel sheet of the second embodiment is different from the first embodiment in that it contains a predetermined amount of V and hardly contains Nb. Other points are the same as those of the first embodiment.

[0361] V: 0.001%~0.2%

[0362] V is an element that finely precipitates in the form of VC and contributes to an increase in the tensile strength of the steel sheet through precipitation strengthening. When the V content is less than 0.001%, it is difficult to obtain sufficient tensile strength. In addition, V has the effect of increasing the n value (work hardening index) which is one of the indicators of formability. On the other hand, when the V content exceeds 0.2%, these effects are saturated, and the economic efficiency is reduced. Therefore, the V content is set to not less than 0.001% and not more than 0.2%. In addition, in order to further enhance the ab...

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Abstract

An inclusion, the major diameter of which is 3.0 [mu]m or greater in a cross section having the plate width direction of a high-strength hot-rolled steel plate as the normal, wherein the maximum value of the major diameter / minor diameter ratio represented by (the major diameter of the inclusion) / (the minor diameter of the inclusion) is 8.0 or less, and the sum of the rolling direction length per 1 mm<2> cross-section of a predetermined inclusion group consisting of a plurality of inclusions, the major diameter of which is 3.0 [mu]m or greater, and a predetermined extended inclusion, the length in the rolling direction of which is 30 [mu]m or greater is 0.25 mm or less. The plurality of inclusions constituting the predetermined inclusion group are clustered at an interval of 50 [mu]m or less with one another in both of the rolling direction and a direction perpendicular to the rolling direction. The predetermined extended inclusion is spaced at an interval of exceeding 50 [mu]m from all inclusions, the major diameter of which is 3.0 [mu]m or greater in at least one of the rolling direction or the direction perpendicular thereto.

Description

technical field [0001] The present invention relates to a high-strength hot-rolled steel sheet with improved formability and fracture characteristics and a method for producing the same. [0002] This application claims priority based on Japanese Patent Application No. 2010-053787 filed in Japan on March 10, 2010 and Japanese Patent Application No. 2010-053774 filed in Japan on March 10, 2010, and the contents thereof are hereby cited . Background technique [0003] Currently, attempts are being made to increase the strength of steel sheets for the purpose of reducing the weight of the steel sheets. In general, increasing the strength of steel sheets leads to deterioration of formability such as hole expandability. Therefore, it is important how to obtain a steel sheet with an excellent balance between tensile strength and hole expandability. [0004] For example, Patent Document 1 discloses that the balance between tensile strength and hole expandability is obtained by o...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00B21B3/00C21D9/46C22C38/58
CPCC21D9/46C22C38/14C22C38/06C21D8/0226C22C38/005B21B3/00C21D2211/005C22C38/001C21D2211/002C21D2211/003C22C38/02C22C38/04C22C38/12
Inventor 高桥雄三土师纯治河野治
Owner NIPPON STEEL CORP
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