EP0050969B1 - Alloy steel powder - Google Patents

Alloy steel powder Download PDF

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Publication number
EP0050969B1
EP0050969B1 EP19810305004 EP81305004A EP0050969B1 EP 0050969 B1 EP0050969 B1 EP 0050969B1 EP 19810305004 EP19810305004 EP 19810305004 EP 81305004 A EP81305004 A EP 81305004A EP 0050969 B1 EP0050969 B1 EP 0050969B1
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EP
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Prior art keywords
final product
powder
alloy
alloy powder
powdered metal
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Application number
EP19810305004
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German (de)
French (fr)
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EP0050969A1 (en
Inventor
Jean C. Lynn
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Amsted Industries Inc
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Amsted Industries Inc
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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%

Definitions

  • the present invention provides a corrosion resistant iron base alloy powder and a method of producing final products using the same. More specifically, the alloy powder is a modification of a type 300 series stainless steel, with increased percentages of silicon and phosphorus. The alloy powder is useful for producing fully dense metal products by powder metallurgy techniques.
  • Type 300 series stainless steels are common stainless steels used in numerous industrial applications. In attempting to make fully dense products from the atomized powder of the alloys of this type of stainless steel using powder metallurgy techniques, it is known that powder alloys of the typical compositions of the alloy series, i.e. type 304 and type 316, are difficult to sinter to full density.
  • the present invention provides a high alloy steel powder useful in forming fully dense, corrosion resistant products by powder metallurgy techniques. A method of producing final products from the steel powder is also provided.
  • the typical composition of the type 300 series stainless steel is changed to provide additional silicon and phosphorus.
  • the invention provides an alloy steel powder containing, by weight: the balance being iron, apart from unavoidable impurities.
  • the difference between the solidus and liquidus temperatures is increased to greater than 25°F (14°C) by the addition of the silicon and phosphorus, and sintering can be commercially performed within the temperature range.
  • the additional silicon is usually added in a pre-alloy operation prior to atomization of the molten alloy to form a powder.
  • the phosphorus can be added in the pre-alloy operation, but can also be added in the pre-alloy operation, but can also be added in an ad-mix operation. In such an ad-mix operation, the phosphorus is added in powder form to the alloy powder, usually in the form of ferro-phosphorus powder.
  • the nickel content of the alloys is preferably about 12%.
  • the silicon content may for example be 2-3% and is preferably about 3%.
  • the phosphorus content is preferably 0.08-0.1 %.
  • the maximum carbon content of the alloys is typically about 0.1%, and if desired carbon, manganese and molybdenum can be absent from the compositions.
  • the powdered metal was blended with about 1% by weight Acrawax (Trademark) for die lubrication purposes. Any similar lubricant may also be used.
  • the sample was compacted in a die at 50 TSI (7047 Kg/cm 2 ), the lubricant was removed in a burn off process and then the compacted sample was vacuum sintered at 2420°F (1327°C) for 90 minutes.
  • the corrosion rate of the final product was 0.1 inch per year (0.25 cm/year).
  • the corrosion test was performed according to practice B of ASTM A 262.
  • the product was also found to be rust free in a 5% salt fog environment according to ASTM B 117-63.
  • the final products can be water quenched to improve corrosion resistance, ductility, toughness and other properties.
  • the final product when water quenched from a solution treatment temperature of 2100°F (1150°C) has an elongation of 40% and an unnotched impact strength of greater than 120 ft-Ib (163 joules).
  • the corrosion rate of the final product was 0.04 in/yr (1 mm/yr) in boiling sulfuric acid according to practice B of ASTM A 262.
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
  • the powdered metal was compacted and sintered in a manner similar to Example 1.
  • the final product had properties similar to the final product in Example 1, except that elongation improved to 26%.
  • the corrosion rate was 0.047 in/yr (1.2 mm/yr).
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
  • the powdered metal was blended with about 1% by weight Acrawax (Trademark) for die lubrication purposes. Any similar lubricant may also be used.
  • the sample was compacted in a die at 50 TSI (7047 Kg/cm 2 ), the lubricant was removed in a burn off process and then the compacted sample was vacuum sintered at 2430°F (1332°C) for 90 minutes.
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
  • the powdered metal was compacted and sintered in a manner similar to that set forth in Example 1.
  • the final product had properties similar to the final product in Example 1, except that the corrosion rate was 0.05 in/yr (1.27 mm/yr).
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
  • the powdered metal was compacted and sintered in a manner similar to that set forth in Example 1.
  • the final product has properties similar to the final product in Example 1, except that the corrosion rate was 0.037 in/yr (0.94 mm/yr).
  • Another iron base alloy that was atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
  • the powdered metal was compacted and sintered in a manner similar to that set forth in Example 1.
  • the final product had properties similar to the final product in Example 1, except that the corrosion rate was 0.049 in/yr (1.25 mm/yr).
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
  • Example 1 The powdered metal was compacted and sintered in a manner similar to that set forth in Example 1.
  • the final product had properties similar to the final product in Example 1.
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
  • the powdered metal was compacted and sintered in a manner similar to that set forth in Example 1.
  • the final product had properties similar to the final product in Example 1, except that the corrosion rate was 0.10 in/yr (2.5 mm/yr).

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Powder Metallurgy (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Description

  • The present invention provides a corrosion resistant iron base alloy powder and a method of producing final products using the same. More specifically, the alloy powder is a modification of a type 300 series stainless steel, with increased percentages of silicon and phosphorus. The alloy powder is useful for producing fully dense metal products by powder metallurgy techniques.
  • Type 300 series stainless steels are common stainless steels used in numerous industrial applications. In attempting to make fully dense products from the atomized powder of the alloys of this type of stainless steel using powder metallurgy techniques, it is known that powder alloys of the typical compositions of the alloy series, i.e. type 304 and type 316, are difficult to sinter to full density.
  • It is believed that the difficulty in sintering is due to the narrow difference between the solidus and liquidus temperatures of these alloys. This difference is approximately 10°F (5°C). Accordingly, the width of the liquid phase sintering range of such an alloy would be so narrow that it would be economically impractical to control the sintering temperature accurately enough in a commercial production operation.
  • Accordingly, it is necessary to increase the difference between the liquidus and solidus temperatures in order that liquid phase sintering can be commercially performed.
  • The present invention provides a high alloy steel powder useful in forming fully dense, corrosion resistant products by powder metallurgy techniques. A method of producing final products from the steel powder is also provided.
  • In the method of producing the alloy powder of the present invention, the typical composition of the type 300 series stainless steel is changed to provide additional silicon and phosphorus. Thus the invention provides an alloy steel powder containing, by weight:
    Figure imgb0001
    the balance being iron, apart from unavoidable impurities.
  • The difference between the solidus and liquidus temperatures is increased to greater than 25°F (14°C) by the addition of the silicon and phosphorus, and sintering can be commercially performed within the temperature range. The additional silicon is usually added in a pre-alloy operation prior to atomization of the molten alloy to form a powder. The phosphorus can be added in the pre-alloy operation, but can also be added in the pre-alloy operation, but can also be added in an ad-mix operation. In such an ad-mix operation, the phosphorus is added in powder form to the alloy powder, usually in the form of ferro-phosphorus powder.
  • The nickel content of the alloys is preferably about 12%. The silicon content may for example be 2-3% and is preferably about 3%. The phosphorus content is preferably 0.08-0.1 %.
  • The maximum carbon content of the alloys is typically about 0.1%, and if desired carbon, manganese and molybdenum can be absent from the compositions.
  • The invention is illustrated in the following examples:
    • Example 1
  • One iron base alloy that was water atomized and screen at -88 mesh to provide a powdered metal had the following initial analysis by weight:
    Figure imgb0002
  • The powdered metal was blended with about 1% by weight Acrawax (Trademark) for die lubrication purposes. Any similar lubricant may also be used. The sample was compacted in a die at 50 TSI (7047 Kg/cm2), the lubricant was removed in a burn off process and then the compacted sample was vacuum sintered at 2420°F (1327°C) for 90 minutes. A final product of over 97% theoretical density, ultimate tensile strength of 100,000 Ib/in2 (7047 Kg/cm2), yield strength of 49,000 Ib/in2 (3452 Kg/cm2), elongation of 10% and unnotched impact strength of 32 ft-Ib (43 joules) was produced. In addition, the corrosion rate of the final product was 0.1 inch per year (0.25 cm/year). The corrosion test was performed according to practice B of ASTM A 262. The product was also found to be rust free in a 5% salt fog environment according to ASTM B 117-63.
  • If desired, the final products can be water quenched to improve corrosion resistance, ductility, toughness and other properties. In the above example, the final product when water quenched from a solution treatment temperature of 2100°F (1150°C) has an elongation of 40% and an unnotched impact strength of greater than 120 ft-Ib (163 joules). The corrosion rate of the final product was 0.04 in/yr (1 mm/yr) in boiling sulfuric acid according to practice B of ASTM A 262.
  • Other samples of similar composition were successfully sintered at temperatures between 2380-2460OF (1305-13500C).
    • Example 2
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
    Figure imgb0003
  • The powdered metal was compacted and sintered in a manner similar to Example 1. The final product had properties similar to the final product in Example 1, except that elongation improved to 26%. The corrosion rate was 0.047 in/yr (1.2 mm/yr).
    • Example 3
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
    Figure imgb0004
  • The powdered metal was blended with about 1% by weight Acrawax (Trademark) for die lubrication purposes. Any similar lubricant may also be used. The sample was compacted in a die at 50 TSI (7047 Kg/cm2), the lubricant was removed in a burn off process and then the compacted sample was vacuum sintered at 2430°F (1332°C) for 90 minutes. A final product of 99% theoretical density, ultimate tensile strength of 93,000 Ib/in2 (6553 Kg/cm2), yield strength of 37,000 Ib/in2 (2607 Kg/cm2), elongation of 45%, unnotched impact strength of greater than 120 ft-Ib (161 joules) and notched impact strength of 17 ft-Ib (23 joules) was produced.
  • In this example, when the final product was gas fan cooled from a solution treatment temperature of 2100°F (1150°C) it has an elongation of 57% and a notched impact strength of 38 ft-in (51 joules). The corrosion rate was 0.16 in/yr (4 mm/yr).
    • Example 4
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
    Figure imgb0005
    Figure imgb0006
  • The powdered metal was compacted and sintered in a manner similar to that set forth in Example 1. The final product had properties similar to the final product in Example 1, except that the corrosion rate was 0.05 in/yr (1.27 mm/yr).
    • Example 5
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
    Figure imgb0007
  • The powdered metal was compacted and sintered in a manner similar to that set forth in Example 1. The final product has properties similar to the final product in Example 1, except that the corrosion rate was 0.037 in/yr (0.94 mm/yr).
    • Example 6
  • Another iron base alloy that was atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
    Figure imgb0008
  • The powdered metal was compacted and sintered in a manner similar to that set forth in Example 1. The final product had properties similar to the final product in Example 1, except that the corrosion rate was 0.049 in/yr (1.25 mm/yr).
    • Example 7
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
    Figure imgb0009
  • The powdered metal was compacted and sintered in a manner similar to that set forth in Example 1. The final product had properties similar to the final product in Example 1.
    • Example 8
  • Another iron base alloy that was water atomized and screened at -88 mesh to provide a powdered metal had the following initial analysis by weight:
    Figure imgb0010
  • The powdered metal was compacted and sintered in a manner similar to that set forth in Example 1. The final product had properties similar to the final product in Example 1, except that the corrosion rate was 0.10 in/yr (2.5 mm/yr).

Claims (8)

1. An iron base alloy powder containing, by weight:
Figure imgb0011
the balance being iron, apart from unavoidable impurities.
2. An alloy powder as claimed in claim 1 which contains about 12% nickel.
3. An alloy powder as claimed in claim 1 or claim 2 which contains 2-3% silicon.
4. An alloy powder as claimed in any one of the preceding claims which contains about 3% silicon.
5. An alloy powder as claimed in any one of the preceding claims which contains 0.08―0.1% phosphorus.
6. An alloy powder as claimed in any one of the preceding claims which contains up to about 0.1% carbon.
7. An alloy powder as claimed in claim 1 having by weight, any one of the compositions set out below:
Figure imgb0012
the balance in each case being iron, apart from unavoidable impurities.
8. Products produced by compacting and sintering a powder as claimed in any one of the preceding claims.
EP19810305004 1980-10-24 1981-10-23 Alloy steel powder Expired EP0050969B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US20052780A 1980-10-24 1980-10-24
US200527 1988-05-31

Publications (2)

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EP0050969A1 EP0050969A1 (en) 1982-05-05
EP0050969B1 true EP0050969B1 (en) 1984-07-04

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EP (1) EP0050969B1 (en)
JP (1) JPS5798659A (en)
BR (1) BR8106856A (en)
CA (1) CA1193891A (en)
DE (1) DE3164598D1 (en)
ES (1) ES506504A0 (en)
IN (1) IN153975B (en)
MX (1) MX156202A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE0102102D0 (en) * 2001-06-13 2001-06-13 Hoeganaes Ab High density stainless steel products and method of preparation thereof

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3620690A (en) * 1968-07-10 1971-11-16 Minnesota Mining & Mfg Sintered austenitic-ferritic chromium-nickel steel alloy
SE372293B (en) * 1972-05-02 1974-12-16 Hoeganaes Ab
DE2708916C2 (en) * 1977-03-02 1985-07-18 Robert Bosch Gmbh, 7000 Stuttgart Use of a high-strength sintered iron alloy

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JPS5798659A (en) 1982-06-18
MX156202A (en) 1988-07-25
IN153975B (en) 1984-09-08
JPS6123841B2 (en) 1986-06-07
CA1193891A (en) 1985-09-24
DE3164598D1 (en) 1984-08-09
ES8300872A1 (en) 1982-11-01
ES506504A0 (en) 1982-11-01
EP0050969A1 (en) 1982-05-05
BR8106856A (en) 1982-07-06

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