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High-strength, high-toughness stainless steel excellent in resistance to delayed fracture

A technology of delayed fracture resistance, high strength and high toughness, which can be used in the field of high-strength and corrosion-resistant stainless steel such as stainless steel screws, and can solve the problem of not being very applicable.

Inactive Publication Date: 2003-04-02
NIPPON STEEL & SUMIKIN STAINLESS STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Among conventional steel grades, although it can improve toughness and delayed fracture resistance, it is not very suitable for screws with high tightening force

Method used

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  • High-strength, high-toughness stainless steel excellent in resistance to delayed fracture
  • High-strength, high-toughness stainless steel excellent in resistance to delayed fracture
  • High-strength, high-toughness stainless steel excellent in resistance to delayed fracture

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Embodiment

[0046] Hereinafter, examples of the present invention will be described.

[0047] Table 1 shows the chemical composition of steels A-I, T-W, AB, AC, AF-AH applicable to the present invention and comparative steels J-S, W-Z, AA, AD, AE, AI-AK.

[0048] The steel A-D applicable to the present invention and the comparison steel J-O are related to the embodiments of the 1st, 2nd, 7th-9th inventions, and its basic composition is 0.2Si-13Cr-2Mo, which affects the surface structure, toughness and delayed fracture performance The amounts of C (%), Mn (%), Ni (%), and N (%) vary.

[0049] Steel E, F applicable to the present invention and comparative steel P are related to the embodiments of the 1st, 2nd, 7th-9th inventions, and their basic components are 0.16C-0.3Mn-1.1Ni-13Cr-2Mo-0.09N, The amount of Si (%) affecting the cold workability was changed.

[0050] The steel G-I applicable to the present invention and the comparative steel Q-S are related to the embodiments of the 1st, 2...

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Abstract

The present invention makes the best use of a low-cost chemical composition in providing a high strength and high corrosion resistance stainless steel, which has improved delayed fracture resistance and toughness in particular, for building and construction uses, and as, for example, a stainless steel tapping screw. The present invention is, specifically, a stainless steel and a stainless steel screw with high strength and high toughness and excellent in delayed fracture resistance, characterized by: comprising, by mass, 0.01 to 0.25% of C, 0.05 to 1.0% of Si, 0.1 to 2.0% of Mn, 0.1 to 3.0% of Ni, 11.0 to 16.0% of Cr, 0.01 to 0.15% of N, and 0.01 to 3.0% of Mo; containing, optionally, 0.001 to 0.005% of B and / or one or more of 0.05 to 0.5% of Ti, 0.05 to 0.5% of Nb, and 0.05 to 0.5% of W; having less than 10% of ferrite in the center portion of the material; and having a mixed structure of martensite and 3 to 30% of austenite in the surface layer from the outermost surface to the depth of at least 1 mum, and a method to produce the same.

Description

technical field [0001] The present invention relates to high-strength and strong corrosion-resistant stainless steel, such as stainless steel screws, which are used in construction materials and the like and in particular have improved delayed fracture resistance and toughness. Background technique [0002] In the past, in high-strength and high-corrosion-resistant stainless steel screws made of martensitic stainless steel, there were always concerns about chipping due to high central strength, low toughness, and delayed fracture. [0003] It has been proposed to add nickel to improve the toughness and delayed fracture resistance of martensitic stainless steel (JP-A-9-206792). [0004] On the other hand, it is known that a dual-phase steel in which the outermost layer is martensite and the center portion is martensite+ferrite has both ductility and strength (JP-A-7-316740). [0005] Among conventional steel grades, although toughness and delayed fracture resistance can be i...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C21D9/00C22C38/00C22C38/42C22C38/44C22C38/54C22C38/58C23C8/26
CPCC22C38/54C22C38/42C23C8/26C21D2211/008C22C38/58C21D2211/001C22C38/001C22C38/44C21D9/0093C22C38/18
Inventor 高野光司吉村公一松井孝至
Owner NIPPON STEEL & SUMIKIN STAINLESS STEEL CORP
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