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Free cutting alloy

a cutting alloy and alloy technology, applied in the field of free cutting alloys, can solve the problems of easy sulfur contamination in the peripheral areas of parts, degrading corrosion resistivity, and easy reduction of corrosion resistivity, so as to prevent or suppress the effect of corrosion resistance, improve the machinability of alloys, and reduce corrosion resistan

Inactive Publication Date: 2008-05-29
ISHIDA CO LTD +5
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0009]Machinability of an alloy can be improved by forming the above described (Ti, Zr) based compound in a matrix metal phase of the alloy. Furthermore, by forming this compound in the alloy, formation of compounds such as MnS and (Mn,Cr)S, easy to reduce corrosion resistivity and hot workability of the alloy, can be prevented or suppressed, thereby enabling corrosion resistivity, hot workability and cold workability to be retained at good levels. That is, according to the present invention, a free cutting alloy excellent in machinability can be realized without any degradation in useful characteristics as an alloy such as hardness, corrosion resistivity, hot workability, cold workability and specific magnetic characteristics.
[0010]Further, a (Ti,Zr) based compound formed in a free cutting alloy of the present invention can be dispersed in the alloy structure. Especially dispersing the compound in an alloy structure can further increase machinability of an alloy. In order to increase the effect, a particle size of the (Ti,Zr) based compound as observed in the structure of a polished section of the alloy is preferably, for example, approximately in the range of 0.1 to 30 μm on the average and further, an area ratio of the compound in the structure is preferably in the range of 1 to 20%, wherein the particle size is defined by the maximum distance between two parallel lines circumscribing a particle in observation when parallel lines are drawn intersecting on a region including the particle in observation while changing a direction of the parallel lines.
[0011]The above described (Ti,Zr) based alloy can include at least a compound expressed in a composition formula (Ti,Zr)4(S,Se,Te)2C2 (hereinafter also referred to as carbo-sulfide / selenide), wherein one or more of Ti and Zr may be included in the compound and one or more of S, Se and Te may be included in the compound. By forming a compound in the form of the above described composition formula, not only can machinability of an alloy be improved, but corrosion resistivity is also improved.

Problems solved by technology

While S, which has widely been used for improvement of machinability, is in many cases added in the form of MnS, addition thereof in an alloy in a large content is causes for degrading corrosion resistivity, hot workability and cold workability of the alloy.
Moreover, when the alloy is exposed to the air, a sulfur component included in the alloy is released into the air in the form of a sulfur containing gas, which causes sulfur contamination in peripheral areas of parts with ease.
Elements such as S. Se and Te, however, deteriorate magnetic properties to a great extent in an electromagnetic stainless steel and the like.
To increase a Cr content in sulfide, however, tends to greatly decrease in machinability and hot workability and therefore, such an alloy has been restricted on its application in many cases.
Although such prior arts as JP11-140597 ('597), JP10-130794 ('794), JP2-170948 ('948), JP63-93843 ('843), JP60-155653 ('653) and USP4,969,963 (Honkura et al.) disclose various free cutting alloys, these alloys are not satisfactory in machinability, sulfur out-gassing characteristics and elimination of Pb content.

Method used

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Examples

Experimental program
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Effect test

example 1

Ferrite Containing Stainless Steel (Corresponding to the First Selection Invention)

[0221]The effects of a free cutting alloy constituted as ferrite containing stainless steel (a first selection inventive steel) were confirmed by the following experiment. First, 50 kg steel blocks with respective compositions in mass % shown in Table 1 were molten in a high frequency induction furnace and ingots prepared from the molten blocks were heated at a temperature in the range of from 1050 to 1100° C. and the ingots were forged in a hot state into rods with a circular section of 20 mm diameter and the rods were further heated at 800° C. for 1 hr, followed by air cooling (annealing) as a source for test pieces.

[0222]While main inclusions of an inventive steel of the present invention was (Ti,Zr)4(S,Se)2C2, other inclusions such as (Ti,Zr)S and (Ti,Zr)S3 are locally recognized in the matrix. Further, in a specimen No. 7 high in Mn content, (Mn, Cr)S is recognized, though in a trace amount. An i...

example 2

Martensite Containing Stainless Steel (Corresponding to the Second Selection Invention)

[0248]The following experiment was performed on martensite containing stainless steel and second selection inventive steel of the present invention. First, 50 kg steel blocks of compositions in mass % shown in Table 3 were molten in a high frequency induction furnace to form respective ingots. The ingots were heated at temperature in the range of from 1050 to 1100° C. to be forged in a hot state and be formed into rods each with a circular section, of a diameter of 20 mm. The rods were further heated at 750° C. for 1 hr, followed by air cooling to be applied to the test.

[0249]In Table 3, specimens Nos. 1 to 19 are second selection inventive steels of the present invention constituted as martensite containing stainless steel. Further, in comparative examples, specimens correspond to stainless steel: a specimen No. 20 corresponds to SUS 410, a specimen No. 21 to SUS 416, a specimen No. 22 to SUS 420...

example 3

Austenite Containing Stainless Steel (Corresponding to the Third Selection Invention)

[0271]An experiment was performed on a free cutting alloy of the present invention constituted as austenite containing stainless steel (a third selection inventive steel). 50 kg blocks of compositions in mass % shown in Table 5 were molten in a high frequency induction furnace to form ingots. The ingots were heated at a temperature in the range from 1050 to 1100° C. and hot forging was applied on the ingot at the same temperature to be formed into rods each having a circular section, of a diameter of 20 mm. Specimens Nos. 1 to 18 and 22 to 26 are steel, corresponding to third selection inventive steels and specimens Nos. 19 to 21 and 27 to 29 are of comparative steels. The specimen No. 19 corresponds to SUS 304, the specimen No. 20 to SUS 303, the specimen No. 27 to SUS 329J4L. Among them, the specimens Nos. 1 to 21 are kinds of steel for use in application of a non-magnetism and the specimens Nos. ...

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Abstract

Provided is free cutting alloy excellent in machinability, preserving various characteristics as alloy. The free cutting alloy contains: one or more of Ti and Zr as a metal element component; and C being an indispensable element as a bonding component with the metal element component, wherein a (Ti,Zr) based compound including one or more of S, Se and Te is formed in a matrix metal phase. The free cutting alloy is more excellent in machinability, preserving various characteristics as alloy at similar levels to a conventional case. The effect is especially conspicuous, for example, when a compound expressed in a chemical form of (Ti,Zr)4C2(S,Se,Te)2 as the (Ti,Zr) based compound is formed at least in a dispersed state in the alloy structure.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the priority of Japanese Patent Application Nos. 11-250902 filed on Sep. 3, 1999, 2000-070257 filed on Mar. 14, 2000, 2000-221433 filed on Jul. 21, 2000, 2000-251602 filed on Aug. 22, 2000, and 2000-251626 filed on Aug. 22, 2000, which are incorporated herein by reference. This application is a continuation-in-part application of U.S. patent application Ser. No. 10 / 847,524, filed May 18, 2004, which is a continuation-in-part application of U.S. patent application Ser. No. 10 / 242,768, filed Sep. 13, 2002, and now abandoned, which is a continuation-in-part application of U.S. patent application Ser. No. 09 / 653,344, filed Aug. 31, 2000, now abandoned.BACKGROUND[0002]The present invention relates to free cutting alloy excellent in machinability.[0003]Alloy has widespread applications because of a variety of characteristics thereof a free cutting alloy excellent in machinability is, in a case, selected for improvement of...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C22C38/60C22C38/18C22C38/06
CPCC22C38/04C22C38/06C22C38/60C22C38/38C22C38/34
Inventor ISHIDAOIKAWA, KATSUNARIEBATA, TAKASHIINOGUCHI, TAKAYUKISHIMIZU, TETSUYAOKABE, MICHIO
Owner ISHIDA CO LTD