GB2038882A - Carburising Sintered High Speed Steel - Google Patents

Carburising Sintered High Speed Steel Download PDF

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Publication number
GB2038882A
GB2038882A GB7937855A GB7937855A GB2038882A GB 2038882 A GB2038882 A GB 2038882A GB 7937855 A GB7937855 A GB 7937855A GB 7937855 A GB7937855 A GB 7937855A GB 2038882 A GB2038882 A GB 2038882A
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GB
United Kingdom
Prior art keywords
workpiece
carbon
high speed
compact
powder
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
GB7937855A
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Davy Loewy Ltd
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Davy Loewy Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Davy Loewy Ltd filed Critical Davy Loewy Ltd
Priority to GB7937855A priority Critical patent/GB2038882A/en
Publication of GB2038882A publication Critical patent/GB2038882A/en
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/24—After-treatment of workpieces or articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23B—TURNING; BORING
    • B23B27/00—Tools for turning or boring machines; Tools of a similar kind in general; Accessories therefor
    • B23B27/14—Cutting tools of which the bits or tips or cutting inserts are of special material
    • B23B27/148—Composition of the cutting inserts
    • 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

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)

Abstract

A high speed steel workpiece, such as a cutting tip, is made by compacting substantially carbon-free high speed steel powder and sintering the resulting shaped compact. The sintered compact is further worked to the required dimensions and carburised at high temperature to introduce carbon. Carburising and nitriding may take place simultaneously at high temperature to introduce carbon and nitrogen. The steel, powder should contain >0.1% carbon.

Description

SPECIFICATION The Manufacture of Workpieces from High Speed Steel In the manufacture of a workpiece such as a cutting tool from high speed steel, it is known to form the workpiece from high speed steel powder by compacting a quantity of the powder to form a compact and subsequently heat treating the powder compact. In view of the hardness of the high speed steel powder, it is necessary to anneal the powder prior to compaction and this adds to the cost of the process. Furthermore, high compacting loads are required to compact the powder into a compact and this means that high load compaction equipment is required and the wear on the compacting tools is considerable.
It is an object of the present invention to provide a process for the manufacture of a workpiece from high speed steel and which has advantages over the known process.
According to the present invention, in a method of manufacturing a workpiece from high speed steel, a quantity of high speed steel powder which is substantially free from carbon is compacted to produce a shaped compact, the compact is sintered to increase its density, the compact is further worked to produce a workpiece having the required dimensions and at least part of the workpiece is carburised at a high temperature to introduce carbon into the workpiece.
The carburising step may be followed by tempering to produce a workpiece of the required hardness.
The use of carbon-free powder enables the powder annealing operation to be avoided.
Furthermore, carbon-free powder offers a higher density at a given pressure than a carboncontaining powder and thus can minimise shrinkage during sintering. Alternatively, the ability to produce a given density at lower pressures may be used to minimise tool loads and wear.
As an example of the process of the invention, a high speed tool steel to BM2 specification except for the omission of carbon is sieved to say one hundred mesh. A quantity of the powder is pressed in a die or in an isostatic press to produce a shaped compact. The compact is then sintered in a controlled atmosphere of say hydrogen or alternatively it may be sintered in vacuum in order to increase the density of the compact. The compact is now of high density but it does not have the exact required dimensions and consequently it is cold coined or forged to produce an article having the required overall dimensions. All or part of the workpiece is then carburised from a carbon-containing atmosphere at high temperature to introduce carbon into the workpiece.The carburisation process continues until a substantially fully carburised material, particularly at the surface thereof, is obtained.
After carburisation, the composition of the workpiece, particularly at the surface thereof which has been in contact with the carburising atmosphere, should be substantially the same as that of the specification of the high speed steel.
For example, high speed steel to BM2 specification includes 6% W, 5% Mo, 4% Cr and 2% V and the powder which is used in this process is substantially free from carbon. After the carburisation step in the process, the specification of the workpiece should be stated above but with the addition of 0.85% C.
After the carburisation step, a tempering process to produce final hardness may be required.
High speed tool steel which is substantially free from carbon contains less than 0.1% carbon.
The invention is suitable for the manufacture of cutting tips.
During the carburisation stage carbon is deposited into the workpiece for a depth of up to .025 inches from the surface. If desired, the atmosphere containing the carbon can also contain nitrogen so that the workpiece is simultaneously carburised and nitrided to introduce both carbon and nitrogen into the workpiece.
Claims
1. A method of manufacturing a high speed steel workpiece, comprising compacting a quantity of high speed steel powder substantially free from carbon to form a shaped compact, sintering the compact to increase its density, further working the compact to produce a workpiece having the required dimensions and carburising at least part of the workpiece at high temperature to introduce carbon into the workpiece.
2. A method according to claim 1 wherein the carburising is followed by a tempering step.
3. A method according to claim 1 or 2 wherein the steel powder is of high speed tool steel substantially free from carbon and sieved to about 100 mesh.
4. A method according to claim 1, 2 or 3 wherein the shaped compact is obtained by pressing the steel powder in a die or isostatic press.
5. A method according to any one of claims 1 to 4 wherein the compact is sintered in a hydrogen atmosphere or in vacuum.
6. A method according to any one of the preceding claims wherein the sintered compact is cold coined or forged to produce a workpiece having the required dimensions.
7. A method according to any one of the preceding claims wherein the workpiece is carburised in a carbon-containing atmosphere at high temperature to deposit carbon into the workpiece for a depth of at least 0.025 inches from the surface.
8. A method as claimed in any preceding claim, wherein at least part of the workpiece is carburised and nitrided simultaneously at high temperature to introduce carbon and nitrogen into the workpiece.
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION The Manufacture of Workpieces from High Speed Steel In the manufacture of a workpiece such as a cutting tool from high speed steel, it is known to form the workpiece from high speed steel powder by compacting a quantity of the powder to form a compact and subsequently heat treating the powder compact. In view of the hardness of the high speed steel powder, it is necessary to anneal the powder prior to compaction and this adds to the cost of the process. Furthermore, high compacting loads are required to compact the powder into a compact and this means that high load compaction equipment is required and the wear on the compacting tools is considerable. It is an object of the present invention to provide a process for the manufacture of a workpiece from high speed steel and which has advantages over the known process. According to the present invention, in a method of manufacturing a workpiece from high speed steel, a quantity of high speed steel powder which is substantially free from carbon is compacted to produce a shaped compact, the compact is sintered to increase its density, the compact is further worked to produce a workpiece having the required dimensions and at least part of the workpiece is carburised at a high temperature to introduce carbon into the workpiece. The carburising step may be followed by tempering to produce a workpiece of the required hardness. The use of carbon-free powder enables the powder annealing operation to be avoided. Furthermore, carbon-free powder offers a higher density at a given pressure than a carboncontaining powder and thus can minimise shrinkage during sintering. Alternatively, the ability to produce a given density at lower pressures may be used to minimise tool loads and wear. As an example of the process of the invention, a high speed tool steel to BM2 specification except for the omission of carbon is sieved to say one hundred mesh. A quantity of the powder is pressed in a die or in an isostatic press to produce a shaped compact. The compact is then sintered in a controlled atmosphere of say hydrogen or alternatively it may be sintered in vacuum in order to increase the density of the compact. The compact is now of high density but it does not have the exact required dimensions and consequently it is cold coined or forged to produce an article having the required overall dimensions. All or part of the workpiece is then carburised from a carbon-containing atmosphere at high temperature to introduce carbon into the workpiece.The carburisation process continues until a substantially fully carburised material, particularly at the surface thereof, is obtained. After carburisation, the composition of the workpiece, particularly at the surface thereof which has been in contact with the carburising atmosphere, should be substantially the same as that of the specification of the high speed steel. For example, high speed steel to BM2 specification includes 6% W, 5% Mo, 4% Cr and 2% V and the powder which is used in this process is substantially free from carbon. After the carburisation step in the process, the specification of the workpiece should be stated above but with the addition of 0.85% C. After the carburisation step, a tempering process to produce final hardness may be required. High speed tool steel which is substantially free from carbon contains less than 0.1% carbon. The invention is suitable for the manufacture of cutting tips. During the carburisation stage carbon is deposited into the workpiece for a depth of up to .025 inches from the surface. If desired, the atmosphere containing the carbon can also contain nitrogen so that the workpiece is simultaneously carburised and nitrided to introduce both carbon and nitrogen into the workpiece. Claims
1. A method of manufacturing a high speed steel workpiece, comprising compacting a quantity of high speed steel powder substantially free from carbon to form a shaped compact, sintering the compact to increase its density, further working the compact to produce a workpiece having the required dimensions and carburising at least part of the workpiece at high temperature to introduce carbon into the workpiece.
2. A method according to claim 1 wherein the carburising is followed by a tempering step.
3. A method according to claim 1 or 2 wherein the steel powder is of high speed tool steel substantially free from carbon and sieved to about 100 mesh.
4. A method according to claim 1, 2 or 3 wherein the shaped compact is obtained by pressing the steel powder in a die or isostatic press.
5. A method according to any one of claims 1 to 4 wherein the compact is sintered in a hydrogen atmosphere or in vacuum.
6. A method according to any one of the preceding claims wherein the sintered compact is cold coined or forged to produce a workpiece having the required dimensions.
7. A method according to any one of the preceding claims wherein the workpiece is carburised in a carbon-containing atmosphere at high temperature to deposit carbon into the workpiece for a depth of at least 0.025 inches from the surface.
8. A method as claimed in any preceding claim, wherein at least part of the workpiece is carburised and nitrided simultaneously at high temperature to introduce carbon and nitrogen into the workpiece.
9. A method according to any one of the preceding claims, wherein the workpiece is a cutting tip.
10. A method of manufacturing a high speed steel workpiece according to claim 1, substantially as described herein.
11. A high speed steel workpiece when manufactured by the method of any one of the preceding claims.
GB7937855A 1978-11-03 1979-11-01 Carburising Sintered High Speed Steel Withdrawn GB2038882A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB7937855A GB2038882A (en) 1978-11-03 1979-11-01 Carburising Sintered High Speed Steel

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB7843138 1978-11-03
GB7937855A GB2038882A (en) 1978-11-03 1979-11-01 Carburising Sintered High Speed Steel

Publications (1)

Publication Number Publication Date
GB2038882A true GB2038882A (en) 1980-07-30

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB7937855A Withdrawn GB2038882A (en) 1978-11-03 1979-11-01 Carburising Sintered High Speed Steel

Country Status (1)

Country Link
GB (1) GB2038882A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0078147A1 (en) * 1981-10-24 1983-05-04 James Neill Holdings Limited Metal strip
US4839139A (en) * 1986-02-25 1989-06-13 Crucible Materials Corporation Powder metallurgy high speed tool steel article and method of manufacture
WO1996041031A1 (en) * 1995-06-07 1996-12-19 Bt-Magnettechnologie Gmbh Process for case hardening higher molybdenum-alloyed sintered steels

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0078147A1 (en) * 1981-10-24 1983-05-04 James Neill Holdings Limited Metal strip
US4839139A (en) * 1986-02-25 1989-06-13 Crucible Materials Corporation Powder metallurgy high speed tool steel article and method of manufacture
WO1996041031A1 (en) * 1995-06-07 1996-12-19 Bt-Magnettechnologie Gmbh Process for case hardening higher molybdenum-alloyed sintered steels
US5881356A (en) * 1995-06-07 1999-03-09 Bt-Magnettechnologie Gmbh Method for the case-hardening of higher-molybdenum-alloy sintered steels

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