GB1580534A

GB1580534A - Method of manufacturing alloy sheet and a sheet of alloy made thereby

Info

Publication number: GB1580534A
Application number: GB2900776A
Authority: GB
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1976-07-13
Filing date: 1976-07-13
Publication date: 1980-12-03

Description

(54) A METHOD OF MANUFACTURING ALLOY SHEET AND A SHEET OF ALLOY MADE THEREBY (71) We, ROLLS-ROYCE LIMITED, formerly Rolls-Royce 1971 Limited, a British Company of 65 Buckingham Gate, London, SWIE 6AT, formerly of Norfolk House, St. James's Square, London SW17 4JR, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a method of manufacturing alloy sheet and to a sheet of metal made thereby, and comprises an improvement in or modification to the invention claimed in our prior patent 1,324,621.

In our above mentioned patent it is explained that the manufacture of sheet from certain high temperature resistant alloys has previously been very difficult because in the manufacture of these sheets by conventional methods the properties of the material are such as to cause severe cracking. Therefore our prior patent contemplates the use of a manufacturing technique in which an alloy comprising: Chromium 2(&num;30% Carbon 0.2-0.75% Tungsten 5--11 Tantalum 0-10 Molybdenum 0-5 Niobium 0-1 Titanium 0-1 Zirconium 0-0.5 Hafnium 0-2 Aluminium 0-8 Nickel 0-15 Boron 00.5 Silicon 0-2 Cobalt balance apart from impurities or Chromium 20-25 Cobalt 5-15 Molybdenum 0-10 Tungsten 0-10 Tantalum 0-5 (Molybdenum + Tungsten + Tantalum at least 5%) Carbon 0.2-0.5 Aluminium 0-2 Titanium 0-2 Niobium 0-1 Hafnium 0-2 Boron 00.5 Zirconium W0.5 Silicon 0-2 Nickel balance apart from impurities is manufactured by forming the alloy into a powder, compacting the powder to form a billet, and rolling the billet to produce a sheet.

It has now been appreciated that it is possible to further improve the properties of the alloys mentioned above by the addition of small quantities of rare earth metals such as Lanthanum, and that the lower limit of the carbon content may be reduced without deleterious effect.

According to the present invention a method of manufacturing alloy sheet from an alloy comprising by weight percent: Chromium 20-30% Carbon 0.1-0.75 Tungsten 5-Il Tantalum 0-10 Molybdenum 0-5 Niobium 0-1 Titanium 0-1 Zirconium 00.5 Hafnium 0-2 Aluminium 0-8 Nickel 0-15 Boron 0--0.5 Silicon 0-2 Lanthanum or 0.02-0.2 other rare earth element Cobalt balance apart from impurities or Chromium 20-25 Cobalt 5-15 Molybdenum (&num;10 Tungsten 0-10 Tantalum 0-5 (Molybdenum + Tungsten + Tantalum at least 5%) Carbon 0.1-0.5 Aluminium 0-2 Titanium 0-2 Niobium 0-1 Hafnium 0-2 Boron 0-0.5 Zirconium 0-0.5 Silicon 0-2 Lanthanum or 0.02-0.2 other rare earch elements Nickel balance apart from impurities comprises the steps of forming the alloy into a powder, compacting the powder to form a billet, and rolling the billet to produce a sheet.

Preferably the alloy is formed into a powder by an atomisation technique; thus it may be melted and allowed to fall in a molten stream which is atomised by ajet of inert gas.

The powder may then be formed into a billet by isostatic pressing or by extrusion and may be subsequently extruded or forged to compact the particles.

The invention also includes an alloy sheet made by the method described above.

Preferred examples of alloys which may be used in the manner of the invention have the following constituents: Compositions C Cr Ni Co W Ta Ti Zr B La Alloy X 0.48 22.2 9.9 Bal 6.7 3.5 0.16- 0.03 0.0050.08 Alloy Y 0.56 20.4 - Bal 9.5 9.0 - 0.06 0.0050.08 In our previous patent reference was made to alloy E which was a preferred embodiment of our invention. We have now carried out experiments with the preferred alloys X and Y above, and their properties are compared with those of alloy E in the table below; it should be noted that these properties are for an alloy in the form of a sheet produced from powder and thus different from those quoted in 1,324,621.

Strength - Temperature for rupture Corrosion Resistance - Temperature in 1000 hours under stress of 5 tsi for 0.003" depth of oxidation in 1000 hours.

Alloy X 930 C) @ Alloy Y 9200 C) 5PhOeweIer Alloy E 7750C) Alloy X 1110 C Alloy Y 10900C Alloy E 10600C It will be seen that although alloy E represented an improvement on the state of the art which existed at the time of application for our patent 1,324,621 particularly in corrosion resistance, the alloys as modified in the manner of the present invention have even better properties.

It should be noted that although the preferred alloys X and Y above include Lanthanum as their rare earth metal addition, it would be possible to use any of the other rare earth metals such as Yttrium or Cerium in similar proportions. However, Lanthanum has been found to be particularly beneficial.

It should also be noted that although the alloys X and Y referred to above include 0.08% of the rare earth addition, we believe that quantities of rare earth in the range 0.02-0.2 percent may be used with beneficial results.

Claims

WHAT WE CLAIM IS:

1. A method of manufacturing alloy sheet from an alloy comprising by weight percent: Chromium - 20-30 Carbon - 0.l&num;).75 Tungsten - 5-11 Tantalum - 0--10 Molybdenum - 0-5 Niobium - (&num;1 Titanium - 0-1 Zirconium - 0-0.5 Hafnium - 0-2 Aluminium - 0-8 Nickel - 0-15 Boron - 0-0.5 Silicon - 0-2 Lanthanum or other rare - 0.02-0.2 earth element Cobalt - balance apart from impurities or Chromium - 20-25 Cobalt - 5-15 Molybdenum - 0-10 Tungsten - 0-10 Tantalum - 0-5 (Molybdenum + Tungsten +Tantalum at least 5%) Carbon - 0.1-0.5 Aluminium - 0-2 Titanium - 0-2 Niobium - 0-1 Hafnium - 0-2 Boron - 0-0.5 Zirconium - 0-0.5 Silicon - 0-2 Lanthanum or - 0.02-0.2 @@@@@ @@@@ @@@@@ @@@@@@@ other rare earth element Nickel - balance apart from impurities comprises the steps of forming the alloy into a powder, compacting the powder to form a billet, and rolling the billet to produce a sheet.

2. A method as claimed in claim 1 and in which the alloy comprises by weight percent: Chromium - 22.2 Carbon - 0.48 Tungsten - 6.7 Tantalum - 3.5 Titanium - 0.16 Zirconium - 0.03 Nickel - 9.9 Boron - 0.005 Lanthanum - 0.08 Cobalt - balance apart from - impurities

3. A method as claimed in claim I and in which the alloy comprises by weight percent: Chromium - 20.

4 Carbon - 0.56 Tungsten - 9.5 Tantalum - 9.0 Zirconium - 0.06 Boron - 0.005 Lanthanum - 0.08 Cobalt - balance apart form impurities 4. A method as claimed in any preceding claim and in which the alloy is formed into a powder by an atomisation technique.

5. A method as claimed in claim 4 and in which the powder is formed by melting the alloy, forming a stream of the molten alloy and atomising the stream in a jet of inert gas.

6. A method as claimed in any preceding claim and in which the powder is formed into a billet by isostatic pressing or by extrusion.

7. A method as claimed in any preceding claim and in which the billet is extruded or forged prior to rolling.

8. A method substantially as hereinbefore particularly described with reference to the examples.

9. An alloy sheet made by the method of any of the preceding claims.