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High-strength PC steel wire

A high-strength, steel wire technology, used in building reinforcements, furnaces, heat treatment equipment, etc., can solve problems such as the reduction of delayed fracture resistance, and achieve the effects of excellent delayed fracture resistance and easy manufacturing methods.

Active Publication Date: 2018-03-27
NIPPON STEEL CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, with the increase in strength of PC steel wire, there is a problem that the delayed fracture resistance characteristic decreases

Method used

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  • High-strength PC steel wire
  • High-strength PC steel wire
  • High-strength PC steel wire

Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0104] Steel grades a to m having the chemical composition shown in Table 1 were heated under the conditions shown in Table 2, hot-rolled, coiled into a ring shape, immersed in a molten salt tank behind the hot-rolling line, and subjected to a lead bath. Quenching treatment, manufacturing wire. Thereafter, the obtained wire rods were drawn into wire diameters shown in Table 2, heated after drawing, and subjected to aging treatment to manufacture high-strength PC steel wires shown in test numbers 1 to 28. Then, the following tests were carried out on these steel wires.

[0105] [Table 1]

[0106]

[0107] [Table 2]

[0108]

[0109] The tensile strength test was performed using a test piece No. 9A in accordance with JIS Z 2241. The results are shown in Table 3.

[0110] The Vickers hardness test was performed in accordance with JIS Z 2244. In calculating the Vickers hardness ratio (Hv S / Hv I ), first, the Vickers hardness (Hv S ) is measured as follows: in the se...

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Abstract

The chemical composition of this high-strength PC steel wire comprises, in mass%, C: 0.90-1.10%, Si: 0.80-1.50%, Mn: 0.30-0.70%, P: 0.030% or less, S: 0.030% or less, Al: 0.010-0.070%, N: 0.0010-0.010%, Cr: 0-0.50%, V: 0-0.10%, B: 0-0.005%, Ni: 0-1.0%, Cu: 0-0.50%, and the remainder is Fe and impurities. The ratio of the Vickers hardness (HvS) of the area 0.1D [D: diameter of steel wire] from thesurface of the steel wire (the surface layer) and the Vickers hardness (HvI) of the area interior to the surface layer satisfies [1.10 < HvS / HvI <= 1.15]. The average carbon concentration of the region from the surface of the steel wire up to 10[mu]m deep (the outermost layer) is no more than 0.8 times the carbon concentration of the steel wire. The metal structure in the region interior to the aforementioned outermost layer region is, by area%, a pearlite structure: greater than or equal to 95%, and has a tensile strength of 2000-2400 MPa. This high-strength PC steel wire has a simple manufacturing method and has excellent delayed fracture resistance.

Description

technical field [0001] The present invention relates to a PC steel wire used for prestressed concrete, etc., and particularly relates to a high-strength PC steel wire with a tensile strength of 2000 MPa or more and improved delayed fracture resistance. Background technique [0002] PC wire is mainly used for tensioning of prestressed concrete for civil engineering and building structures. In the past, PC steel wire was produced by subjecting piano wire to lead bath quenching to form a pearlite structure, then drawing and stranding, and aging treatment in the final process. [0003] In recent years, high-strength PC steel wires with a tensile strength exceeding 2000 MPa have been demanded in order to reduce construction costs and reduce the weight of structures. However, there is a problem that the delayed fracture resistance characteristic decreases with the increase in strength of the PC steel wire. [0004] As a technique for improving the delayed fracture resistance of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C21D8/08C22C38/54
CPCC21D8/065C21D8/08C21D9/525C22C38/001C22C38/002C22C38/02C22C38/04C22C38/06C22C38/16C22C38/24C22C38/32C22C38/00C22C38/54C21D2211/009E04C5/08
Inventor 小此木真平上大辅山田真人大岛克仁田中秀一
Owner NIPPON STEEL CORP