Thermal tool steel

A hot tool quality technology, applied in the field of hot tool steel, can solve problems such as carbides and non-metallic inclusions without considering the size

Inactive Publication Date: 2003-08-20
NIPPON KOSHUHA STEEL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, these known technologies do not consider the size of carbides and non-metallic inclusions, so they only improve machinability at the expense of other properties

Method used

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Embodiment Construction

[0012] The present invention will be described in further detail below. When the inclusions are reduced, the thermal crack resistance can be improved. However, depending on the composition of the steel, the improvement effect is not the same, and the machinability deteriorates significantly. Therefore, it is difficult to achieve both thermal crack resistance and machinability. The inventors found that if the particle size of carbides and non-metallic inclusions is controlled, it is possible to achieve both thermal crack resistance and machinability.

[0013] As a method of extending tool life, it has been known in the past that the more inclusions, the better the machinability. However, the inventors found that in quenched and tempered steel with a hardness exceeding 45HRC, regardless of the amount of inclusions, the machinability is good in some cases and poor in some cases. Therefore, the inventor believes that in a state of good purity, by appropriately controlling the particle...

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PUM

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Abstract

A hot toolsteel comprises 0.10 to 0.70% C, 0.10 to 0.80% Si, 0.30 to 1.00% Mn, 0.007 to 0.020% P, 3.00 to 7.00% Cr, W and Mo in 0.20 to 12.00% in terms of (1 / 2W+Mo) alone or in combination, 0.10 to 3.00% V, 0.05 to 0.80% Ni, <=6.50% Co and <=0.150% S, and the balance substantially Fe with inevitable impurities. The cleanliness of nonmetallic inclusions is <=0.020%, and, on annealing, the area ratio of carbides and nonmetallic inclusions having particle diameters of >1.0 mu m is <=0.004%. The hot tool steel has improved heat check and erosion resistances, and has remarkably improved machinability by the above technical measure.

Description

Technical field [0001] The invention relates to a hot tool steel used for hot forging dies, extrusion dies, die-casting dies, etc., in particular to a hot tool steel for controlling carbides and non-metallic inclusions and improving machinability, thermal cracking resistance and melting loss resistance. Background technique [0002] In the past, a technique for improving the toughness of hot tool steel by improving the purity of non-metallic inclusions has been disclosed (Japanese Patent No. 2809622, Patent Application Publication No. 61331 / 1999). In addition, some people have proposed a technology to improve the machinability by increasing the number of inclusions and making the shape of the inclusions spherical (Electric Steel, Vol. 64, No. 3, pages 191 to 201, Figures 2 and 4, Japanese No. 61331 / 1999, 60585 / 1998 Invention Patent Application Publication). However, the above-mentioned prior art evaluates inclusions based on standards such as JISGO555 or ASTM E45-76, and therefo...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C22C38/00C22C38/48C22C38/52C22C38/60
CPCC22C38/02C22C38/04C22C38/44C22C38/46C22C38/52
Inventor 吉田润二山下广
Owner NIPPON KOSHUHA STEEL
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