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

A delayed fracture resistant, high-strength, high-toughness technology applied to high-strength and corrosion-resistant stainless steel such as stainless steel screws. It can solve problems such as screws that are not very suitable for use in the field

Inactive Publication Date: 2002-02-06
NIPPON STEEL & SUMIKIN STAINLESS STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

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 Construction

[0044] Hereinafter, examples of the present invention will be described.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] 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). Among conventional steel grades, although toughness and delayed fracture resistance can be improved...

Claims

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Application Information

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