US2892703A - Nickel alloy - Google Patents

Description

United States Patent ass'znos ICKE ALLOY -No Drawing. 'ApplicationMarch5, 1958 "SerialiNo. 719,204

' 4fClaims. (Cl. 75-123 This inventionrelatestto ferrous alloys and ferrous -alloy articles for luse v atyhigh temperatures, referring especially to alloy articles-suitable for use in applications where highstrength at, elevated temperatures is required.

Thetrend inmodern engineering is towards the utili- ;Zation ,of high temperatures for many and diverse'opera- -tions. As an example,chemicalprocesses are conducted .todayat high temperatures, a notable instance being in the field of petroleum refining. Alloys with high strength :at elevated temperatures are also required as furnace parts-in the form of supportsand channelsiof one kind ;or another inwhich processes are operated at high temperatures. Such furnaces, may contain'tubes, either cast orwrought, ortrolls that act as conveyors forparts moving-through the furnaces, or they may contain metal trays :that-are constantly being brought in and out of thefurnace withfrequentheating.andcooling resulting in drastic-changes in temperatures. .In some instances, ends a :of metaltubes, usually referred to in the art as reactor .tubes, areoperatedin such fashion that one end is hot and theother is cool. In this case the necessity for having available metal-that will Withstand temperature vari- "ationsas well :as rapidchangesin temperature is a requirement that is diificult to meet.

The aforementioned furnaces and furnace parts that havebeen used successfully in commercial processes in :the past have'been produced from alloys that-contain in addition to chromiu'msubstantial proportions of nickel. tlnvariably, these alloys have contained anywhere from :about.30%ito 60% nickel. It is awell known fact that in recent years the industrialdemands for nickelhave been at least equal to, and-in some cases in excess of, availability.

' Thisstate 'of afiairs has created anunfavorablecon- *dit'ion in regard-to-the economic use of alloys at the high temperatures. Ithasbrought stress on the users of highinickel content alloys -to .such an extent that substitutes .have'been tried with resulting unsatisfactory service and increased cost in operation. The supplyof nickel has .notincreased'to such -an.extent that it is a-free commodity, andxcontinued hardship will confront.both the producers and users of the high-nickel-content alloys. in .orderto obtain materials of construction that are .eco- :nomically suited, for high :temperature applications.

Other applications ,in'which high-nickel alloysv are. used are;insuch devices assuperchargers, gasturbines; jet propulsionaapparatus;and the like, land it is necessary in these uinstances.forithepmaterials to withstand deterioration at :high temperatures and under high :rnechanical stress vwithtout failure due to --:excess 1 defamation or: cracking.

Usually the temperatures involved in all suchtypesof applications are in excess of 1200 F., and in many 1nstances the temperatures :generally exceed 1500 F. Typical of the compositions that have been used in such applications are alloys containing from 15% to 20% of chromium and from 35% to 60% of nickel, the remainder being iron with minor percentages of other constituents such as carbon, manganese, silicon and impurities such as phosphorous and sulphur.

2,892,703 Patented .June 30, 19 59 ICC . 2 The'principal object of this invention is to provide new ferrous alloys which contain much less than about 30% of nickel and which will successfully resist oxidation and 'will withstandhigh applied stresses at temperatures of 5 from about l200 to somewhat in excess of about This object is attained by.the.present. invention which provides alloys of new compositions and properties. The

principal ingredients of the alloys of this invention are carbon, chromium, nickel, manganese,.nitrogen and columbium with adequatepercentages of silicon for quality purposes, and incidental impurities, such as phosphorous and sulphur.

Itisimportant thatcertain of these elements should be present in the proper proportions and percentages.

The nickel should not be less than about 15% nor more than about and the combined chromium and nickel I content should range between about 25% and about 50%,

and the manganese should range between about 5% and 20 about 15%. "When columbium and nitrogen are present in certain percentages in alloys containing those percentages of cl1romium,-nickel and manganese, the alloys will have high temperaturestrength quite comparable with that of prior highchrome, high nickel alloys containing 5 from 35% to'60% of nickel. And even When the nickel content is as low as 10% or 15%, the present alloywill have high'temperaturestrength heretofore thought to be impossible to] attain inalloys of that low nickel content.

This new and unexpectedhigh temperature strength-is traceable in large part to' the presence of the three elements, high manganese, columbium and nitrogen, as'is indicated by the fact'that When either columbium or nitrog'en is omittedfthe high temperature strength is great ly reduced.

Inalloys of the foregoing composition it is to be under stood that the remainder of the composition is iron with usual impurity amounts of sulphur and phosphorous, medium carbon, and moderate amounts of silicon.

This, invention'is also embodied in alloys having the 4 following intermediate composition range within the foregoing broad range:

Carbon From about 30% to about .50%.

Chromium From about 15% to 25% maximum. Nickel From about 10% to about 25%.

.Manganese From about 5% to about 15 "Silicon From about .9% to about 1.5%.

Nitrogen From about .05 to about .5 Columbium From about .75 to about 1.5%.

the remainder being iron with not more than about .05

.ofeach of phosphorous and sulphur.

A-narrower andpreferred range of ingredients is as follows:

Carbon From about .30%to about 50%.

' Chromium From about 19% to about-22%. Nickel From about 19% to about 22%. "Manganese From about 8% to about 11%.

Silicon From about .9% to about 1.5

Nitrogen From about .05% to about .5

Columbium From about .75 to about 1.5%.

i .theremainder being iron with not more than about 04% of each of phosphorous and sulphur.

Apreferred alloy:has.the :following composition:

with the remainder being iron with not more than about .025 of phosphorous and not more than about .022% of sulphur.

Physical properties of the preferred composition are shown 1n the following table:

Short Time High Temperature Properties:

Tensile Strength (p.s i) 54, 100 30, 600 Elongation in 2 11. 5 14. 0 Reduction in Area 10. 4 37. 8 Room Temperature Physical Properties:

Yield Point (p.s.i.) 53,250 Tensile Strength (p.s.i.).. 83, 750 Elongation in 2. ll. 0 Reduction in Area" 12. 6

Stressrupture at 1,600 F. and 7,000 p.s.i. load: Time in Hours to Rupture 1,103 Hrs. Air Oxidation Resistance at 1,800 F .0097696 inch per year.

more resistant to air oxidation, than alloys which have been used extensively heretofore to resist high temperatures and which contained a much higher nickel content. Since it was generally believed that a high nickel content was required to confer high heat resisting properties on the alloy, it is a surprising and unobvious discovery that even better properties at high temperatures can be obtained by this invention wtih greatly reduced amounts of nickel.

It is to be understood that many different alloys may be made within the limits of the foregoing broad composition ranges and that each such alloy will embody the present invention and will, at least to an appreciable extent, possess the above-stated properties.

All of the test results described in the foregoing tables have been obtained on cast samples, but it should be pointed out that this in no way limits the invention as all of these alloys are capable of being hot worked into various and sundry items such as billetspforgings, bars, sheet, and strip. It should be understood that when it is necessary to produce such items-for fabrication into equipment serving at temperatures of about 1200 F., this practice is also included and forms a .part of the invention.

Alloys embodying the present invention may be made either from virgin metal or scrap metal. A convenient way to make these alloys is to select scrap metal of the chrome-nickel types and to proportion such scrap in a manner to obtain the above-specified chrome-nickel contents. Since the chrome-nickel scrap contains iron and iron contains such elements as .carbon and impurity amounts of phosphorous and sulphur, the desired amounts of iron and such elements may be provided by proportioning the chrome-nickel scrap oradding iron or iron containing alloys[ The manganese may be in the form of term-manganese. The nitrogen may be conveniently added in the form of high nickel bearing term-chrome alloy. All these metals may be melted down at the same time.

Having thus described this invention in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same,

and having set forth the best mode contemplated of carrying out this invention, we state that the subject-matter which we regard as being our invention is particularly pointed out and distinctly claimed in what is claimed, it being understood that equivalents or modifications of, or substitutions for, parts of the above specifically described embodiments of the invention may be made without departing from the scope of the invention as set forth in what is claimed.

What is claimed is:

1. A nickel chrome iron alloy having a tensile strength above about 50,000 pounds per square inch at 1400 R, an air oxygen resistance of less than about .010 inch per year at 1800 F., and a resistance to rupture for about 1100 hours under a stress of about 7000 pounds per square inch applied at about 1600 F. and consisting essentially of not less than about 10% or more than about 25%, of nickel sufiicient chromium not exceeding about 25% to bring the combined nickel and chromium content to between about 25% and about 50%, between about 5% and about 15% of manganese, between about .75 and about 1.5% of columbium, between about .05% and about .5% of nitrogen, the remainder being moderate amounts of silicon and iron containing medium carbon and usual impurity amounts of sulphur and phosphorous.

2. A nickel chrome iron alloy having a tensile strength above about 50,000 pounds per square inch at 1400 R, an air oxygen resistance of less than about .010 inch per year at 1800 F., and a resistance to rupture for about 1100 hours under a stress of about 7000 pounds per square inch applied at about 1600 F. and consisting essentially of between about 30% and about 5 of carbon, between about 15% and about 25% of chromium, between about 10% and about 25% of nickel, between about 5% and about 15% of manganese, between about .9% and about 1.5 of silicon, between about .75% and about 1.5 of columbium, and between about .05% and about .5% of nitrogen, the remainder being iron with not more than about .05 of each of sulphur and phosphorous.

3. A nickel chrome iron alloy having a tensile strength above about 50,000 pounds per square inch at 1400 R, an air oxygen resistance of less than about .010 inch per year at 1800 F., and a resistance to rupture for about 1100 hours under a stress of about 7000 pounds per square inch applied at about 1600 F. and consisting essentiallyof between about 30% and about .50% of carbon, between about 19% and about 22% of chromium, between about 19% and about 22% of nickel, between about 8% and about 11% of manganese, between about .9% and about 1.5% of silicon, between about .75% and about 1.5 of columbium, and between about .05 and about .75% of nitrogen, the remainder being iron with not more than about .04% of each of sulphur and phosphorous.

4. A nickel chrome iron alloy having a tensile strength above about 50,000 pounds per square inch at 1400 R, an air oxygen resistance of less than about .010 inch per year at 1800 F., and a resistance to rupture for about 1100 hours under a stress of about 7000 pounds per square inch applied at about 1600 F. and consisting essentially of .38% of carbon, about 21.4% of chromium, about 20.6% of nickel, about 9.3% of manganese, about .94% of silicon, about 1.02% of columbium, and about 20% of nitrogen, the remainder being iron with not more than about .04% of each of sulphur and phosphorous.

No references cited.

Claims (1)

1. A NICKEL CHROME IRON ALLOY HAVING A TENSILE STRENGTH ABOVE ABOUT 50,000 POUNDS PER SQUARE INCH AT 1400* F., AN AIR OXYGEN RESISTANCE OF LESS THAN ABOUT 0.10 INCH PER YEAR AT 1800* F. AND A RESISTANCE TO RUPTURE FOR ABOUT 1100 HOURS UNDER A STRESS OF ABOUT 7000 POUNDS PER SQUARE INCH APPLIED AT ABOUT 1600* F. AND CONSISTING ESSENTIALLY OF NOT LESS THAN ABOUT 10% OR MORE THAN ABOUT 25%, OF NICKEL SUFFICIENT CHROMIUM NOT EXCEEDING ABOUT 25% TO BRING THE COMBINED NICKEL AND CHROMIUM CONTENT TO BETWEEN ABOUT 25% AND ABOUT 50%, BETWEEN ABOUT 5% AND ABOUT 15% OF MANGESE, BETWEEN ABOUT .75% AND ABOUT 1.5% OF COLUMBIUM, BETWEEN ABOUT .05% AND ABOUT .5% OF NITROGEN, THE REMAINDER BEING MODERATE AMOUNTS OF SILICON AND IRON CONTAINING MEDIUM CARBON AND USUAL IMPURITY AMOUNTS OF SULPHUR AND PHOSPHOROUS.