USRE16683E - Steel of high-temperature stability - Google Patents

Description

Reissued July 19, 1 927.

are required to maintain their physical properties at substantially high temperatures. I use of tungsten insmall proportions to preat high temperatures.

The primary object of my invention is to produce a high tensile steel of cheap manufacture that will be capable of resisting high temperatures without substantial loss of strength. v A further object of my invention is the use of an addition agent to preserve at high temperatures the physicalcharacteristics of mal temperatures.

. It is well known to add chromium to steel in order to increase its tensile strength in its untreated state.- Chrome steels, of this description, cannot be submitted to high temperatures without losing their characteristic properties of high tensile strength.

I have found, however, that small additions of tungsten in conjunction, with chromium serve. to modify the eflect of high temperature on the steel, while at the same normal temperatures without impairing the high tensile strength conferred thereon by the chromium. i

I have found that a position for a low carbon steel capable of withstandin exposure to high temperatures,

properties, isas follows:' Chromium from a fraction of 1% to 2%, tungsten from a fraction of 1% to 2%, manganese from .5 to

1.5%, carbon up to 15%, and the balance 0 iron with the usual propdrtions of sulphur,

phosphorus and silicon. I

A preferred composition that has given very satisfactory results contains besides iron; chromium .43, tungsten 1.30,.1nanganose .64, carbon .33.v After treatment at 1600" F. and oil quenching and ,retreatment at 1200 and air quenching, this composition gave the following physical tests: Yield point 143,500 lbs; tensile strength 0 163,000; elongation 14%. Testbars from the same heat and similarly heat, treated,

STEEL OF HIGH-TEMPERATURE STABILIT'I This invention relates to alloy steels that It relates more. particularly to the serve said physical properties of the steel a steel having high tensile properties at nortimeimproving the ductilityof the steel at suitable range of com- 5 without suhstantial loss of its physical UNITED STATES ATENT OFFICE.

WILLIAM ROBERT SHEER, 0F BETHLEHEM, PENNSYLVANIA, ASSIGNOR'TO BETHLE- HEM s'rnnn COMPANY. 7

Ho Drawing. Original No. 1,624,075, dated A ril 12, 1921, Serial no. 752,929, filed November 29, 1924.

' Application for reissue filed May 26, 1927. semi No. 194,520. i

' the following results:

' Reduction 0 Tensile Temperature F. Yield. strength per oent.

120, 000 155, 000 43. 38 120, 000 151, 0(1) 44. 85 105, 000 130, 030 5a. 31 90, 000 124, 000 58. 57 000 119, 000 60. 32 Normal M3, 500 1 000 48.

Ihave also 'found that the addition of tungsten up to 2% in the case of a low carbon steel containing no chromium, ren ders the steel more stable at high temperatures.

From the view-point of cheapness and for purposes of general utility, such as bolts,

. studs and nuts exposed to high temperatures, rollers pins and links for hot.con-

veyors and :ior similar purposes, I prefer to use a composition within the following limits:

Chromium .30 to .60; tungsten .90 to 1.15' manganese .90 to 1.10; carbon .30 to .40, and the balance iron with customary proportions of sulphurf phosphorus and silicon. In

other words, for the purposes named, I use a steel having broadly chromium'up to 1% with tungsten and manganese each substantially twice the chromium.

For certain special purposes requiring high initial tensile strength and high initial elastic limit, which properties are to be substantially reserved at high temperatures, as f or examp e, oil cracking stills operating at a temperature or 600 F. and an. internal pressure of 150 lbs. per sq. inch, I consider that a low carbon steel having approximately equal proportions of chromium and tungsten, each up to 2%, with manganese up to 1.5% is eminently suitable. The higher content ofchromium used in this case serves to insure a close grained structure in the metal whereby it is less subject to corrosive deterioration from contact with the furnace gases, while the tungsten, as heretofore explained, servesto preserve the physical qualmy alloy in respect of their maintaining to a substantial degree their ph sical proper ties at high temperatures," I have also discovered that by appropriate treatment I can endow my alloy with ,very hightensile qualities at normaltemperatures. For example, a low carbon .steelcontaining chromium 0.43, un ten 1.30 and manganese 0.64, when rined at 1600 F. and oil quenched; and retreated at 800- F. and air cooled, gave the following results: Yield 190,000 lbs., tensile strength 222,000 elongation 12%. Having thus described my invention what I vclaim as new and desire to secure by Letters Patent is:

1. A low-carbon, tough, and readily workable commercial steel containing between $0 and .60 chromium, between .50 and .80 manganese and with tungsten between 1% and 1.50% added thereto to preservethe strength of the steel at high temperatures.

a v 2. A steel containing as the essential ingradients other than iron, carbon from low to medium content, chromium .43%, tungsten- 1.3% and manganese not exceeding .64%.

3. A steel containing as the essential ingredients other than iron, carbon from low mess to medium content, chromium .30% to .60%,

l gsten .90% to 1.15% and manganese t to exceed 1.10%.

4. A steel having a yield point of 190,000,

tensile strength 222,000 andelongation 12%, containing as the essential ingredients other than iron, carbon from low to medium content, chromium .43%,

manganese 154%.-

tungsten 1.30%, and

5. A steel containing as the essential ingredients other'than iron, carbon from low to medium content, chromium in effective amounts but not more than .60% and tungsten in efiective amounts not; more than v 1.3%, having high tensile strength and elastic limit both at atmospheric'and high tem- ,peratures.

6. An article of manufacture different temperature conditions composed of a steel containing as the essential constituents other than iron, carbon from low to medium content, chromium in effective "amount but appreciably less than 1% and tungstenfronpa fraction of 1% to 2%. WILLIAM ROBERT SHIMER.

7 adapted to be subiected to great stresses under widely-