US3627514A - High-speed steel containing chromium tungsten molybdenum vanadium and cobalt - Google Patents
High-speed steel containing chromium tungsten molybdenum vanadium and cobalt Download PDFInfo
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- US3627514A US3627514A US822672A US3627514DA US3627514A US 3627514 A US3627514 A US 3627514A US 822672 A US822672 A US 822672A US 3627514D A US3627514D A US 3627514DA US 3627514 A US3627514 A US 3627514A
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- nitrogen
- cobalt
- steel
- steels
- carbide
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
- C22C38/30—Ferrous alloys, e.g. steel alloys containing chromium with cobalt
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/02—Making ferrous alloys by powder metallurgy
- C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
- C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
- C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
Definitions
- This invention relates to a tool steel consisting essentially of, in weight percent, carbon 1 to 1.4, chromium 4 to 6, vanadium 1 to 1.5, tungsten 7.5 to 13, molybdenum 3.5 to 7, cobalt 9 to 15, nitrogen at least about .03 and preferably .03 to .08, and the balance iron.
- the invention also relates to a tool steel compact of this steel produced by a powder-metallurgy technique also in accordance with this invention.
- the tool steel article is characterized by a combination of good cutting performance and machinability.
- a more specific object of the invention is to provide a tool steel that may be austenitized at the high temperature required to take the carbide formers present in the material into solution, without causing attendant grain coarsening.
- Another more specific object of the invention is to provide a tool steel alloy wherein a good combination of machinability and cutting perforance is achieved by a critical combination of a controlled nitrogen content in combination with specific carbide formers wherein a fine, uniform carbide distribution is maintained even in the presence of high austenitizing temperatures.
- Another related object of the invention is to provide a tool steel compact produced in accordance with a powderice metallurgy process that results in said article having a desired combination of good machinability and cutting performance resulting from the presence of a fine, uniform carbide distribution throughout the compact.
- FIGS. 1A and 1B are photomicrographs of a steel in accordance with the present invention and a conventional tool steel, respectively, wherein the effect of the invention is shown in respect to the carbide form, size and distribution;
- FIGS. 2A and 2B are three-dimensional plots of grain size vs. austenitizing temperature and carbon content, and again size vs. austenitizing temperature and carbon plus nitrogen content, respectively.
- the tool steel of the invention consists essentially of, in weight percent, carbon 1 to 1.4, chromium 4 to 6, vanadium 1 to 1.5, tungsten 7.5 to 13, molybdenum 3.5 to 7, cobalt 9 to 15, nitrogen at least about .03 and preferably .03 to .08, and the balance iron.
- this steel is used in the form of a powder of about --8 mesh U.S. Standard. This powder is placed in a. metal container, which is gas tight. The container is heated to an elevated temperature in excess of about 2000 F. and its interior is pumped to a low pressure whereupon the gaseous reaction products and principally those resulting from the reaction of carbon and oxygen are removed.
- Compacting may be by mechanical apparatus wherein the container is placed in a die and a ram is inserted to compact the container and charge.
- the container may be placed in a fluid-pressure vessel, commonly termed an autoclave, where a fluid pressurizing medium, such as helium gas, may be employed to provide the desired compacting.
- a fluid pressurizing medium such as helium gas
- the carbon content of the alloy, as above disclosed, must be properly balanced against the carbide-forming elements, such as vanadium, tungsten and molybdenum, to produce the carbide precipitation upon cooling from austenitizing temperature required to prevent softening during subsequent annealing.
- carbide-forming elements such as vanadium, tungsten and molybdenum
- vanadium functions to produce carbides that have been found to be wear-resistant and thus contribute greatly to the tool life of articles made from the alloy.
- these wear-resistant carbides make the steel difficult to machine and grind.
- Tungsten provides carbides that retain hardness at high temperature, principally because they do not appreciably or substantially grow and agglomerate at high austenitizing temperatures and, therefore, grain coarsening of the alloy is retarded. Molybdenum acts in the same manner as tungsten with respect to carbide formation, except that tungsten is critical for the purposes of pre- 4 **d.
- Rex 71 P/M steels listed in Table I two additional compacts with similar compositions except for having nitrogen contents of .003 and 017% were prepared.
- the processing of the steel it is austenitized at a high tem perature on the order of 2200 F. and then hardened during cooling.
- the austenitizing step involves heating to dissolve the carbide-forming elements. After quenching from austenitizing temperature, the material is subjected to reheating at a lower temperature at which the carbideforming elements are precipitated in the form of carbides. This, of course, produces the desired secondary hardening.
- the carbon is dissolved in the austenite, which upon cooling transforms to a required hard carbon-containing martensite.
- the carbideforming elements remain in solution in the martensite.
- the carbide-forming elements during tempering combine with the carbon in the steel and form carbides.
- This carbide precipitation results in the desired secondary hardening.
- the cobalt present in the alloy contributes to the retention of hardness at high temperatures.
- the presence of nitrogen in an amount of at least .03%, and preferably within the range of .03 to 08%, is necessary to achieve a fine carbide distribution. This result of nitrogen has been found not to increase significantly at nitrogen levels substantially above .08%.
- the maximum amount of nitrogen present in the alloy is limited by the solubility of nitrogen in the melt, unless the nitrogen is
- the Rex 71 P/M materials were made from particles of the alloy of a mesh size of -+325 US. Standard.
- a charge of these particles was placed into a mild steel cylinder about 4 in. long and having a 3% in. diameter.
- This container. which was gas tight, was heated to a temperature of 2100 F. for about 4 hours at which time the container interior was connected to a pump which was used to remove the gaseous reaction products from the container.
- the container at a temperature of about 2000 F., was placed in a die and a ram of a ZOO-ton press was used to compact the container and charge to a density greater than 95%. After compacting, the material was forged into 4 in. square bars, during which operation a density of essentially 100% was achieved.
- the other steels, as reported in Table I were conventionally cast and wrought from 50-pound. air-induction heats.
- the average tool life of the Rex 71 P/M lathe cutting tools is four times that of Rex 49 (M41) during use in the test to continuously turn the reported difiicult-tomachine alloys at identical speed, feed, and depth-ofcut.
- the Rex 71 P/ M cutting tools averaged 16 minutes before failure in cutting at 35 s.f.p.1n. a workpiece of AISI H13 die steel having a hardness of 53 R whereas, the best performance of tools made from conventional high-perf0rrnance high-speed steels was an average of 2.8 mins. for M4] and 6.2 mins. for M42 cutting tools used to cut the same workpiece.
- a cutting tool of the steel of the invention also showed superior performance when compared with cutting tools of conventional tool steels in cutting a workpiece of C125 AVT titanium.
- the Rex 71 P/ M cutting tool of the invention averaged 86 mins. before failure; whereas, the cutting tools made from M42 and M41 averaged 53.8 mins. and 22.7 mins., respectively, before failure.
- FIGS. 2A and 2B A metallographic examination of the samples, which were austenitized at temperatures between 2200 F. and 2270 F showed that the high nitrogen Steels B, D, and F retained a fine grain structure in the presence of higher temperatures than did the nitrogen-free Steels A, C, E, and G with an equivalent interstitial alloy content.
- FIGS. 2A and 2B This comparison between the high-nitrogen steels and the nitrogen-free steels is shown in FIGS. 2A and 2B.
- FIG. 2A the total interstitial content consists of carbon; whereas, with FIG. 2B the interstitial content consists of carbon plus nitrogen.
- the range of total interstitial content is from .85 to 1.10%.
- a tool steel characterized by a combination of good cutting performance and machinability consisting essentially of, in weight percent, carbon 1 to 1.4, chromium TABLE IV.CHEMICAL COMPOSITION OF EXPERIMENTAL STEELS Molybdenum high-speed steels, composition, weight percent C N M11 S P Si V W 0. 86 0. 01 0. 37 0. 0l9 0. 010 0. 35 3. 87 l. 75 l. 75 0. 85 0. 06 0. 3O 0. 018 0. 015 0. 29 3. 74 2. l1 1. 80 1. 00 0. 01 0. 31 0. l3 0. 014 0. 4. 00 2. 13 l. 66 0. 91 0. 08 0. 0. 0. 13 0. 016 0. 28 3. 95 2. 29 1.66 1. O9 0. 01 0. 25 0. 020 0. 020 0. 27 3. 75 2. 05 1. 75 U. 98 0. 08 0. 24 0. 020 0. 020 0. 35 3. 75 2. 05 1. 75 0. 94 0. 01 0. 54 0. 020 0. 020 0. 25 3. 76 2. 05 1. 75
Abstract
Description
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US82267269A | 1969-05-07 | 1969-05-07 |
Publications (1)
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US3627514A true US3627514A (en) | 1971-12-14 |
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US822672A Expired - Lifetime US3627514A (en) | 1969-05-07 | 1969-05-07 | High-speed steel containing chromium tungsten molybdenum vanadium and cobalt |
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Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2327568A1 (en) * | 1972-06-12 | 1974-01-03 | Asea Ab | Process for the production of blanks from metal powder |
US3929471A (en) * | 1971-12-22 | 1975-12-30 | Hitachi Ltd | High speed steel having high wear-resistance |
US4140527A (en) * | 1976-05-21 | 1979-02-20 | Kobe Steel, Ltd. | Nitrogen containing powder metallurgical tool steel |
US4242130A (en) * | 1977-12-27 | 1980-12-30 | Thyssen Edelstahlwerke Ag | High-speed steel |
DE2737208C2 (en) * | 1977-08-18 | 1986-06-19 | MTU Motoren- und Turbinen-Union München GmbH, 8000 München | Process for encapsulating a molded body made of ceramic |
US4780139A (en) * | 1985-01-16 | 1988-10-25 | Kloster Speedsteel Ab | Tool steel |
US4957550A (en) * | 1987-05-06 | 1990-09-18 | Manufacturers Hanover Trust Co. | Ultrasonic machining tool for machining orthodontic brackets |
US5176272A (en) * | 1991-03-25 | 1993-01-05 | United Plastic Films, Inc. | Container for spooled materials |
-
1969
- 1969-05-07 US US822672A patent/US3627514A/en not_active Expired - Lifetime
Cited By (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3929471A (en) * | 1971-12-22 | 1975-12-30 | Hitachi Ltd | High speed steel having high wear-resistance |
DE2327568A1 (en) * | 1972-06-12 | 1974-01-03 | Asea Ab | Process for the production of blanks from metal powder |
US4140527A (en) * | 1976-05-21 | 1979-02-20 | Kobe Steel, Ltd. | Nitrogen containing powder metallurgical tool steel |
DE2737208C2 (en) * | 1977-08-18 | 1986-06-19 | MTU Motoren- und Turbinen-Union München GmbH, 8000 München | Process for encapsulating a molded body made of ceramic |
US4242130A (en) * | 1977-12-27 | 1980-12-30 | Thyssen Edelstahlwerke Ag | High-speed steel |
US4780139A (en) * | 1985-01-16 | 1988-10-25 | Kloster Speedsteel Ab | Tool steel |
US4957550A (en) * | 1987-05-06 | 1990-09-18 | Manufacturers Hanover Trust Co. | Ultrasonic machining tool for machining orthodontic brackets |
US5176272A (en) * | 1991-03-25 | 1993-01-05 | United Plastic Films, Inc. | Container for spooled materials |
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