Tool steel for hot working, tool for hot working and plug for producing seamless pipe

A technology of thermal processing and tool steel, which is applied in the manufacture of tools, metal processing equipment, metal rolling, etc. It can solve the problems of loss of heat insulation effect of surface pressure and deterioration of wear resistance, deformation, and Cr burning resistance.

Inactive Publication Date: 2006-06-14
NIPPON STEEL CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0016] However, the plug in (a) has insufficient high-temperature strength of the base metal and adhesion of scale, and cannot ensure a sufficient life when piercing a long billet, that is, when piercing and rolling with a long piercing length.
[0017] For plugs (a) to (c), the scale on the front end of the plug with the highest surface pressure and increased temperature melts during the pierci

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment

[0095] Sixty types of alloy steels having the chemical compositions shown in Tables 1 and 2 were melted in the atmosphere, and the obtained steel ingots were hot forged, then externally cut, and formed into plugs for piercing and calendering machines for seamless pipe production.

[0096] The plug that will be formed into a specified shape will be burned in an LNG combustion atmosphere (volume%, 10% CO 2 , 2% O 2 , 20%H 2 O, the rest: N 2 ), heated at various temperatures and times shown in Table 3 and Table 4, and formed oxide skin layers of various thicknesses also shown in Table 3 and Table 4.

[0097] Piercing rolling was performed using each of the obtained plugs. In piercing and rolling, a round billet made of SUS304 with the following dimensions is pierced and rolled into a hollow shell with the following dimensions. The plug continuously feeds the piercing of multiple billets. The piercing conditions were as follows.

[0098] Dimensions of steel billet and hollow...

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PUM

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Abstract

The present invention is a tool steel for hot working, and the oxide scale formed on the surface thereof has good adhesion and lubricity and high strength. The tool steel contains C: 0.05-0.5%, Si: 0.1-1%, Mn: 1.6-3.5%, Ni: 0.05-0.5%, Mo: 2-5%, W: 2-5%, Cu: 0.05- 0.5%, and the remainder is substantially composed of Fe. One or more of Cr, Co, REM, Ti, Nb, V, Zr, and B may also be contained. The surface of a tool made of this steel is covered with an oxide scale with a thickness of 50 to 1500 μm. A typical example of the tool is a piercing plug for seamless pipe production.

Description

technical field [0001] The invention relates to a tool steel for hot working and a tool for hot working. The tool steel of the present invention is suitable as a raw material for a plug of a piercing calender (for example, a Mannesmann piercer) used in the production of a seamless pipe made of a high-Cr alloy steel and a Ni-based alloy. The so-called high-Cr alloy steel is steel represented by stainless steel containing 13% or more of Cr. Background technique [0002] At present, the calenders used to manufacture seamless steel pipes, among them, the plugs for the piercing and calendering machines represented by the Mannesmann piercing machine are made of steel with a basic composition of 3%Cr-1%Ni-the rest of Fe. Plugs are used after heat treatment to form scale on the surface. The plug is used for piercing when ordinary steel is used to make seamless steel pipes. [0003] However, when piercing and rolling seamless pipes made of high-Cr alloy steel represented by stainl...

Claims

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Application Information

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IPC IPC(8): C22C38/00B21B25/00
CPCC22C38/42B21B25/00C22C38/005C22C38/02C22C38/04C22C38/44C22C38/52
Inventor 安乐敏朗五十岚正晃山川富夫下田一宗日高康善
Owner NIPPON STEEL CORP
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