Carbon tool steel strip

a tool steel and tool steel technology, applied in the field of carbon tool steel strips, can solve the problems of insufficient studies on what metallographic structure is used, and achieve the effect of optimum hardness and fatigue resistance as well as blanking properties

Inactive Publication Date: 2015-01-29
HITACHI METALS LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The invention provides a special carbon tool steel strip that has better properties for blanking and fatigue, making it suitable for use in various materials like springs and valves.

Problems solved by technology

However, sufficient studies have not been made on what metallographic structure is appropriate as a carbon tool steel strip in order to achieve both fatigue properties necessary for use as a spring or a valve and blanking properties important in a manufacturing process.

Method used

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[0039]The present invention will be described in more detail with the following Examples.

[0040]A carbon steel raw material was melt, cast and then hot-rolled to provide a hot-rolled material. The hot-rolled material was repeatedly cold-rolled and annealed to prepare a cold-rolled material A of a carbon tool steel strip having a thickness of 0.30 mm and a cold-rolled material B having a thickness of 0.20 mm.

[0041]The thickness and chemical composition of the cold-rolled materials A and B are described in Table 1.

TABLE 1ThicknessComposition (mass %)Material(mm)CSiMnCrBalanceA0.300.9650.2450.4400.131Fe and inevitableimpuritiesB0.200.9650.2450.4400.131Fe and inevitableimpurities

[0042]The cold-rolled materials A and B were quenched and tempered to produce carbon tool steel strips.

[0043]Area ratio of carbides having an equivalent circle diameter of not less than 0.5 μm in a metallographic structure was varied by changing quenching conditions. The quenching and tempering conditions are sho...

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Abstract

Provided is a carbon tool steel strip suitable for use in various spring materials, valve materials, and the like, in which press punching properties and fatigue characteristics are enhanced. A carbon tool steel strip having a thickness of 1 mm or less and a carbon tool steel composition containing 0.8-1.2% C by mass %, wherein the carbon tool steel strip has a Vickers hardness of 500-650 (Hv), and when a cross-section at the center in the sheet thickness direction of the carbon tool steel strip is viewed with the plane of observation in a direction at a right angle to a rolled surface of the carbon tool steel strip and in the length direction of the carbon tool steel strip, the area ratio of carbides having an equivalent circle diameter of at least 0.5 μm among the carbides present in the metallographic structure is 0.50-4.30%.

Description

TECHNICAL FIELD[0001]The present invention relates to a carbon tool steel strip suitable for use in various springs or valve materials, such as shock absorbers or flapper valves.BACKGROUND ART[0002]Conventionally, a carbon tool steel strip suitable for use in springs, valves, or the like is rolled to a predetermined thickness, then quenched and tempered to adjust target properties, and then processed into a target shape for use by e.g. blanking.[0003]For carbon tool steel used after quenching and tempering in this manner, JP-A-2006-63384 (Patent Literature 1), for example, proposes to improve impact properties by controlling an amount of residual carbides in a metallographic structure of the carbon steel. The proposed high carbon steel member has the improved impact properties by controlling a volume % (Vf) of unsolved carbides in a matrix within a range of 8.5<15.3×C%−Vf<10.0.CITATION LISTPatent Literature[0004]Patent Literature 1: JP-A-2006-63384SUMMARY OF INVENTION[0005]A c...

Claims

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Application Information

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IPC IPC(8): C22C38/18C22C38/02C22C38/04
CPCC22C38/18C22C38/02C22C38/04C21D9/46C21D8/0205C21D8/0236C21D8/0247C21D9/52C22C38/00Y10T428/12
InventorUENO, TOMONORIFUJIHARA, HIROYOSHIKISHIGAMI, ICHIROU
OwnerHITACHI METALS LTD