US2087431A - Method of rolling rustless iron and product thereof - Google Patents

Description

Patented July 20, 1937 Alexander L. Feild, Baltimore, Md, assignor, by

mesne assignments, to Rustless Iron and Steel Corporation, Baltimore, Md., a corporation; of

Delaware NolDrawing. Application January 4, 1934,

' Serial No. 705,281

7 Claims. (01. 80- 60) This in'vention relates to rustless iron manufactures'and more particularly to highly heat resistant manufactures of the class indicated.

Among-the objects of my invention isthe pro- 5 duction of strong, ductile and're'adily workable products or manufactures, suchas sheet, strip and bar stock, which are highly heat'jresistant and corrosion resistant under conditions of acid, alkali or salt atmospheresat high temperatures,

and yet which lend themselves to convenient and economical working, as by machining, punching, blanking, deep-drawing, spinning, upsetting or, other known and commercially used forming op erations, into various ultimate'articles of manufacture, such as oil burner parts, roasting trays, heat treatment boxes, airplane exhaust stacks, tubes for 'heat exchange apparatus furnace parts and supports, fluid valves for oxidizing gases, as in blow torches and orgy-acetylene 0 welding apparatus, and the like. i j,

The invention .accordingly'consists in the features of construction, combinationof elements and mixtureof materials as described herein and the scope of the application of. which is indicated in the following'clainis.

As conducive to a clearer understanding of certain features of my invention it may be noted at this point'that rustless iron and steel in sheet, strip and bar stock of-low and intermediate chromium contents (12% to 17%) are useful in the production of a wide variety of hardenable articles, such as tools, cutlery'and'the like, as well as a'number of unhardenable products, such as decorative trim for architectural applications, automobile trim and similar uses where corrosion resistant characteristics are desired at room temperature, or at temperatures somewhat above this value, and under conditions fostering corrosion. This class of manufactures, and the various articles made therefrom, however, are neither designed nor adaptable for high temperature duty, especially'high temperature duty under strongly oxidizing or reducing conditions.

One of the outstanding objects of my invention is the efficient and economical production of heatresistant sheet, strip or bar stock, which is strong, reasonably ductile and unhardenable by heat treatment, in convenient sizes for handling and shipping to customer fabricators for use in the ready fabrication of a variety of highly heat resistant articles, a number of which are set forth above, peculiarly adapted to withstand the corrosive efiects of furnace gases, sulphur fumes, moisture and like oxidizing or reducing agents at high temperatures.

Referring now more particularly-to-the prac tice of my invention, ingots, blooms orblllets of rustless iron, produced for example as described in my Patent No..1,925,182 of September 5, 1933 entitled ,Process for the manufacture of rustless iron, and analyzing approximately 20% to 22% chromium, .05% to 20% carbon; with a per'mis-. sible'silicon content up to about 2%, and the balance substantially iron, are hot rolled into sheet and strip. This hot-rolled sheet and strip is then annealed and pickled and then preferably cold rolled to sheet or stripof desiredthickne'ss. The" sheet or strip. is subsequently, trimmed or slitted and made into a roll convenient 'for handling. Y

To achieve sheet, strip or bar stock of 1 high tensile strength, goodimpact value and fine surface texture,cle'an. and free of surface scale at a minimum of expense-the'r'olling operation is preferably carried out. at room' temperature using smooth, burnished, hardened and tempered alloy steel rolls. A. total, reduction of the sheet or strip ,bar stock of at least about 50%..in the cold rolling operation assures a high grade product; v

While the' large percentages of chromium employed give; the product desired heat resistant characteristics, the workability, of the, material is inclined'to suffer. The very low carbon contents employed, however, permit an increased workability of the metal in the presence of;the se high percentages offchromium, achieving a manufacture of reasonably good working characteristics but one which is essentially .unhardenable by heat treatment.

The sheet or stripisdense, tough, strong and shows a clean, bright surface. This product ormanufacture lends itself toanumber of hot and. cold working operations to achieve awide variety of articles, parts and accessories of exceptional heat resistant characteristics under oxidizing-or reducing atmospheres at sustainedor intermit- ,t'ent high temperature conditions ,up to about.

1050" C. q The rustless iron sheet or strip' may be formed as by punching, blanking, deep-drawing, spin-. ning', upsetting and the like and then welded,

to give a variety of articles, accessories and machine parts for high temperature uses, such as fluid valves for oxidizing gases, furnace bars and supporting elements, needle valves for blow torches and oxy-acetylene welding .apparatus, orifices and valve seats for machinery or apparatus where high temperature oxidizing and reducing conditions are encountered. a a I The workability of the heat resistant rustless iron sheet, strip or bar stock; is appreciablyimproved by including in the metal a supplementary addition of manganese of from about 35% .to-

2%. Since the cost of making this supplementary addition is not particularly great, the improved working characteristics of the metal usually .warrant such an addition.

sheet, strip or bar stock of somewhatimpr'oved resistance'to chloride atmospheres underhigh temperature conditions is achieved by supplementing the analysis set forth above with approximately .25%to 2% of molybdenum: furthermore, this supplementary element effects a sounder-and more dense metal of generally improved corrosion resistant and heat resistant characteristics. Theuse of a'minimum'of this material is desired, however, since it is quite expensive and directly adds to the cost of the metal.

sheet or strip, such as in the matter ,of deepdrawing.

While in the illustrative embodiment of my invention set forth above heat resistant sheet,,

strip or bar stock, unhardenable by heat treatment, containing, in addition to iron, chromium,

and carbon, is specifically described, it be understood that I such a manufacture including one or more oi thesupplement'ary ingredients,

silicon, manganeseImolybdenum, nickel and copper, either singly'or in combination, may beemployed in accordance with the teachings of my invention to achieve highly beneficial re- Thus-it will be seen that there has been provided in this invention a product ormanufacture in which the various objects hereinbefore set forth, together with many thoroughly practical advantages, are successfully achieved. 'It will be seen that the highlyheat'resistant sheot,,.strip" 'and' bar stock, of high chromium contents and low carbon contents, which are unhardenable by 1 heat treatment, readily lend themselves to economical and efllcient working or forminginto a wide variety of heat resistant articles, accessories or apparatus parts adapted to withstand the many tryingconditions of actual high temperature use. y H

As many possible embodiments may be made of my invention and as many changes may be made in the embodiment hereinbefore set forth,

um 20 per cent to 22 per cent, carbon .05 per cent to .20 per cent, wlth the balance substantially iron, and cold-rolled to a total reduction in sectional area 0! about per cent.

2. In the production of heat-resistant sheet or strip oi high tensile strength and of fine'texture, the art which includes, hot-rolling ingots, blooms or billets analyzing approximately, chromium 20 per cent to' 22 per cent, carbon .05 per cent to .20 per cent, and the balance substantially iron, to sheet or strip and then cold-rolling these products to eflect a reduction in area of atleast about 50 percent in] order to achieve sheetor. strip of desired strength and texture. I

3. In the productionof heat-resistant sheet or strip of high tensilestrength and of fine texture,

the art" which includes, cold-rolling hot-rolled sheet or'strip comprising approximately, chromium 20 per cent to 22 percent. carbon .05 cent to .20 per cent, 'andthe balance substan: tially iron toefi'eot a reduction in sections-lama of at least about 50 percentv thereby achieving desired strength and texture. 1

4'. As an article of manufacture heat-resistant sheet or strip of high tensile strength, good impact. value and fine texture, comprising approximately ,20 per cent to 22 percent chromium,

.25 per cent to 2 per cent silicon, .05 per cent to .2 per cent carbon and the balance; substantially iron, and cold rolled to a total reduction in sectionalareato at least about 50 per cent. I

5. As an article of manufacture heat-resistant sheet or strip of high tensilestrength, good im, pact value and fine texture, comprising app'mxi-j mately 20 ,per cent to 22 percent chromium, .25 per cent to 2j per ,cent molybdenum, .05 per. cent to .2 per cent carbon and the balance substantially iron, and cold rolled to a total. reduc tion in sectional area to at least about 50 per cent.

' 6.As a. articleof mannerisms-reams sheet or strip of high tensile strength, good im pact value andfine texture, comprising-approximately 20 per cent to 22 per cent chromium. .25 per centto 2 per cent nickel,=.05per cent to .2pericent carbon and the balance;substantially iron, andcold rolled to a totalreductionin sectional area to at least about 50 per cent.; a

7. As an article of manufacture heat-resistant sheet or strip of high tensile strength, good-impact value and fine texture. comprising approxi-',;

mately 20 per cent to 22 percent chromium, approximately .05 carbon and the balance substantially 'iron and, cold rolled to atotal reduction in sectional area to at least approximately 50 per cent. r