High-carbon steel wire rod with high strength and high toughness

A high-strength, high-toughness technology, applied in the direction of manufacturing tools, furnace types, furnaces, etc., can solve the problems of reverse V-type segregation, insufficient, and insufficient segregation grain refinement.

Inactive Publication Date: 2006-03-08
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Therefore, the thrust of increasing the electromagnetic stirring in the crystallizer is limited
In addition, the equiaxed crystals obtained by electromagnetic stirring are relatively large equiaxed crystals, and there is also the problem that the segregated grains of the central segregation (the size of the obvious solute-enriched part near the center of the slab) cannot be sufficiently refined
[0008] On the other hand, if the reduction time of the soft reduction method is appropriate, a very large central segregation suppression effect can be obtained, but if the reduction is too early or too late, reverse V-type segregation and V-type segregation will occur.
Generally speaking, there is inhomogeneity in the growth of the solidified shell of continuous casting, and it is sometimes not sufficient to use only the light reduction method.

Method used

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  • High-carbon steel wire rod with high strength and high toughness
  • High-carbon steel wire rod with high strength and high toughness
  • High-carbon steel wire rod with high strength and high toughness

Examples

Experimental program
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Effect test

Embodiment 1

[0066] The following examples are given to describe the present invention in more detail.

[0067] The hard steel wires with the chemical composition shown in Table 1 were used. After continuous casting, they were hot-rolled to become steel wires with a diameter of 11 mm, and then directly lead-bath quenched or reheated-lead-bath quenched under various conditions. (Lead bath quenching conditions: reheating at 950°C for 5 minutes → isothermal phase transition at 540°C for 4 minutes).

[0068] The lead-bath quenching material was subjected to mounting grinding and chemical corrosion with dodecanesulfonic acid, and the central area (r<0.2 d) Area ratio of proeutectoid cementite. In addition, mount grinding was carried out and chemical etching was carried out with nital etching solution, and the size of the microscopic martensite grains in the C section was determined by SEM observation. Moreover, the number density, size distribution and chemical composition of the inclusions w...

Embodiment 2

[0074] The molten steel containing C: 0.80%, Si: 0.20%, Mn: 0.70%, P: 0.010%, and S: 0.01% is smelted in a converter, and Zr is added to the ladle after adding Ti or Al.

[0075] The molten steel was cast with a bloom continuous casting machine. In the continuous casting machine, electromagnetic stirring is carried out in the crystallizer or in the casting stream, or the casting is carried out in a state of stopping stirring without electromagnetic stirring. In addition, depending on the situation, the light reduction method is used to apply the reduction at the end of the solidification. The size of the billet is 300mm×500mm. The slab was cut, and the solidification structure, center segregation, and inclusions were evaluated by the above method (the slab was rolled into a wire rod after casting, and the area ratio of proeutectoid cementite was measured).

[0076] In Table 3, Comparative Steel 8 is a slab obtained without adding Zr, and almost no equiaxed crystals are forme...

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Abstract

It is intended to provide a high strength high toughness steel wire suitable for use in PC steel wires, zinc plated steel twisted wires, steel wires for springs, suspension bridge cables, etc. A piano wire rod or hard steel wire rod of 170 kgf/mm<2> or greater tensile strength and 30% or more rupture drawing, having a structure composed mainly of pearlite, wherein the average value of pro-eutectoid cementite area ratio in a central region extending from the center of the wire rod to less than 20% of the radius of the wire rod is 5% or below or wherein the micromartensite size in C-section is 100 mum or less is obtained by subjecting a hard steel wire rod whose steel chemical components, chemical composition of contained inclusions, size and numerical density have been specified to hot rolling and subsequently to either directly patenting treatment or, via reaustenitization, patenting treatment.

Description

technical field [0001] The present invention relates to piano wires or hard steel wires that can be used as PC steel wires, galvanized steel strands, steel wires for springs, steel wire ropes for suspension bridges, and the like. In addition, the present invention also relates to a manufacturing method for obtaining a slab with good internal quality that does not generate center segregation and porosity in the process of casting molten steel. Background technique [0002] When manufacturing high-carbon hard steel wire rods, the hot-rolled wire rods are usually subjected to lead bath quenching and wire drawing processing one or more times, and finally processed into a predetermined wire diameter. The high-carbon hard steel wire rods are guaranteed to reach a predetermined strength At the same time, it is necessary to ensure sufficient performance for toughness, which is evaluated by reduction of area, etc. [0003] It has been confirmed that increasing the amount of C in the...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/14C22C38/52C21D9/52C21C7/04C22C38/60
Inventor 山崎真吾西田世纪梶谷敏之山田亘西川宜孝室贺也康小宫伸介
Owner NIPPON STEEL CORP
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