High-strength steel member

A high-strength steel and component technology, applied in the field of high-strength steel components, can solve the problems of ductility or toughness reduction, quenching cracks, etc., and achieve the effect of excellent delayed fracture resistance

Inactive Publication Date: 2020-01-03
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, if hydrogen intrudes into the steel member from the atmosphere during heating, it may cause quenching cracks after quenching
In addition, for example, when the tempering temperature is as low as 150 to 200°C like high-strength steel members, the hydrogen intruded into the steel member during quenching will not be released sufficiently during tempering, so the ductility or toughness after tempering may be reduced. reduce

Method used

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  • High-strength steel member
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Examples

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Embodiment

[0141] Examples are given below to further describe the present invention in detail. However, these respective Examples do not limit the present invention.

[0142] The test material having the chemical composition shown in Table 1 was heated to the temperature shown in Table 2, then hot rolled at the finish rolling temperature shown in Table 2, and cooled to 700°C at the average cooling rate shown in Table 2, Thereby, it was rolled to φ20mm, and an annular notched test piece (notch depth 2mm, notch bottom radius 0.25mm, notch angle 60 degrees) made of round bar steel with a size of φ10mm×L50mm was produced.

[0143] Heat the test piece under the conditions of simulating carburizing heating atmosphere or RX gas heating (1 atmosphere pressure, 50% hydrogen and Ar mixed atmosphere, heating temperature 1000°C, heating time 30 minutes), at a rate of 40°C / s or less Cooling rate Water cooling to 20°C for quenching, followed by tempering at 150°C for 20 minutes.

[0144] However, c...

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Abstract

Provided is a high-strength steel member which has a predetermined chemical composition, and a tensile strength of at least 1000 Mpa, and which contains: at least 0.10% by area of at least one Ti precipitate which has an average circle equivalent diameter of 30-200 nm at a position of 1 mm deep from the surface of the steel member, and is selected from the group consisting of Ti carbides, Ti nitrides and composite compounds thereof; and at least 0.5 mass ppm of non-diffusible hydrogen, in hydrogen temperature-programmed desorption analysis, released in a temperature range of 400-800 DEG C.

Description

technical field [0001] The invention relates to a high-strength steel component. Background technique [0002] Among the steel members used in machinery, automobiles, bridges, and buildings, steel members that require high strength are used after quenching and tempering chrome steel or chrome-molybdenum steel specified in JIS G 4104 and JIS G 4105. . In addition, like a gear, there is also a high-strength steel member obtained by carburizing and then quenching. [0003] In quenching, quenching is performed after heating to a high temperature at which the steel member becomes an austenite phase. However, if hydrogen invades the steel member from the atmosphere during heating, quenching cracks may occur after quenching. In addition, for example, when the tempering temperature is as low as 150 to 200°C like high-strength steel members, the hydrogen infiltrated into the steel member during quenching will not be released sufficiently during tempering, so the ductility or tough...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D1/06C22C38/38C22C38/58C21D8/06
CPCC21D1/06C21D6/002C21D6/005C21D6/008C21D8/06C21D8/065C22C38/001C22C38/004C22C38/02C22C38/04C22C38/06C22C38/20C22C38/22C22C38/24C22C38/26C22C38/28C22C38/32C22C38/38C22C38/50C22C38/58C22C38/44
Inventor 山崎真吾真锅敏之
Owner NIPPON STEEL CORP
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