Steel wire rod having excellent drawability and fatigue properties, and manufacturing method of the same

A technology of steel wire rod and axis, applied in the field of steel wire rod, can solve the problem of difficult inclusions, and achieve the effect of excellent fatigue performance and excellent drawability

Inactive Publication Date: 2007-03-14
KOBE STEEL LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, when the molten steel treatment method, that is, the contact mixing method of slag and molten steel is not suitable, it is difficult to reduce the inclusions sufficiently
While JP-A 2000-212636 and JP-AH10-102132 describe the control of blowing gas flow rate during refining, the gas flow rate in both cases is high, so inclusions due to slag are easily generated

Method used

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  • Steel wire rod having excellent drawability and fatigue properties, and manufacturing method of the same
  • Steel wire rod having excellent drawability and fatigue properties, and manufacturing method of the same
  • Steel wire rod having excellent drawability and fatigue properties, and manufacturing method of the same

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0082]

[0083] 240 tons of various molten steels in which P has been reduced to 0.007-0.020% and S has been reduced to 0.002-0.01% in the molten steel pretreatment process are mixed with 0-5 tons of cold iron and / or 0-4 Tons of steel scrap are loaded into the converter together. At that time, molten iron, chilled iron, and steel scrap were mixed together so that the average P concentration of all iron raw materials was 0.020% or less. In the converter, the iron raw material is decarburized and blown to have a predetermined concentration, and then poured into a ladle, followed by composition adjustment (for the composition, see Table 1 below) and slag refining in a ladle furnace. The slag in ladle refining is CaO / SiO 2 0.7-1.7 and Al 2 o 3 4-25% CaO-SiO 2 -Al 2 o 3 base slag. Argon is used as the stirring gas during ladle refining, and the gas flow rate is 0.0003-0.012Nm 3 / min changes within the range of per ton of molten steel. Gas agitation times were in each cas...

Embodiment 2

[0107]

[0108] Perform molten iron pretreatment, converter operation, slag refining, continuous casting, blooming and hot rolling as in Example 1 to obtain a steel wire rod with a diameter of 8 mm, then measure the composition of inclusions in the obtained steel wire rod in the same manner as in Example 1 , size and quantity. As an example of the detailed measurement results of the inclusion morphology, the measurement results of No. 18 are shown in Table 5, and the measurement results of No. 22 are shown in Table 6. Similar measurements were made for other examples.

[0109] Then, the fatigue performance in the case where the steel wire rod was used as a spring was evaluated according to the following method.

[0110] [Evaluation method]

[0111] The fatigue properties of steel wires with a diameter of 8.0 mm were evaluated by Nakamura type rotation-bend fatigue test.

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Abstract

A steel wire rod is obtained, in which a gas flow rate during gas stirring in molten steel treatment is controlled to be 0.0005 Nm<3> / min to 0.004 Nm<3> / min per molten steel of 1 ton, thereby the rod satisfies a specified composition, and oxide base inclusions in any section including an axis line of the steel wire rod satisfy the following composition X, the inclusions having width of 2 Am or more perpendicular to a rolling direction, wherein the number of the oxide base inclusions of the following composition A is 1 to 20, and the number of the oxide base inclusions of the following composition B is less than 1. The composition X: when the compound of the inclusions is converted to Al<2>O<3>+MgO+CaO+SiO<2>+MnO=100%, Al<2>O<3>+CaO+SiO<2>>=70% is achieved. The composition A: when the compound of the inclusions is converted to Al<2>O<3>+CaO+SiO<2>=100%, 20%<=CaO<=50% and Al<2>O<3><=30% is achieved. And the composition B: when the compound of the inclusions is converted to Al<2>O<3>+CaO+SiO<2>=100%, CaO>50% is achieved. In the steel wire rod, the drawability and fatigue is largely improved.

Description

technical field [0001] The present invention relates to a steel wire rod having excellent drawability and fatigue properties, and to a method of manufacturing such a steel wire rod, and in particular to a steel wire rod in which hard and relatively low ductility non-metallic inclusions are reduced, thereby improving drawability and fatigue properties, and relates to a useful method for fabricating such steel wires. Background technique [0002] When there are hard and relatively low ductility non-metallic inclusions (especially oxide-based inclusions, hereinafter sometimes simply referred to as "inclusions") in the steel wire, the non-metallic inclusions will breakage during processing into ultra-fine steel wires such as tire cords. In addition, when the steel wire rod is used to manufacture a spring, fatigue fracture starts from non-metallic inclusions under the condition of loading repeated stress to obtain a product (spring). Therefore, non-metallic inclusions must be m...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/06C22C38/08C22C38/18C22C38/20C22C33/04
Inventor 木村世意三村毅出浦哲史
Owner KOBE STEEL LTD
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