US1624075A - Steel of high-temperature stability - Google Patents

Description

Patented Apr. 12, 1927.

f UNITED STATES WILLIAM ROBERT SHIKEB, 01

lo Drawing.

This invention relates to alloy steels that are required to maintain their physical properties at substantially high temperatures. It relates more particularly .to the use of tungsten in small proportions to preserve said physical properties of the steel at 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.

A further object of my invention is the use of an addition agent to preserve at high temperatures the ph ical characteristics of a steeel having hig tensile properties at normal 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 chr0- mium serve-to modify the effect of high temperature on the steel, while at the same time improving the ductility of the steel at normal temperatures without impairing the high tensile strength conferred thereon by the chromium.

I have found that a suitable range of composition for a low carbon steel capable of withstanding exposure to high temperatures, without substantial loss of its physical properties, is as 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 .75% and the balance iron with the usual proportions of sulphur, phosphorus and silicon.

A preferred composition that has given very satisfactory results contains 'beside's iron; chromium .43, tungsten 1.30, manga-- nese .64, carbon .33. .After treatment at 1600 F. and oil quenching and retreatment 163000; elongation 14%. Test bars from the same heat and similarly heat treated,

when tested at different temperatures gave the following results:

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

BETHLEHEM, PENNSYLVANIA, ASSIGNOR '10 BETHLE- HEM COMPANY.

' STEEL or HIGH-TEMPERATU E STABILITY.

Application filed November 29, 1924. Serial No. 752,929.

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 conveyors and for-similar purposes, I refer to use a composition within the ollowing 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 sulphur, hosphorus and silicon. In other words, ihr the urposes named, I use a steel having bro 1y chormium 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 preserved at high temperatures, as for'example, oil cracking stills operating at a temperature of 600 F. andan 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 of cromium used in this case serves to insure a close grained structure in the metal wherebyit is less subject to. corrosive deterioration from contact with the furnace .gases', while the tungsten, as heretofore explained serves to preserve the physical qualities of the steel at the high temperaturesto which it is exposed.

Aside from the distinctive properties of my alloy in respect of their to a substantial degree their physical proper ties at. high temperatures, I'have also dis covered that by appropriate treatment I can endow my alloy with very high tensile qualities at normal example, a low carbon steel containing chromium 0.43, tungsten 1.30 and manganese 0.64, when hardened at 1600 F. and oil quenched and retreated at 800 F. and air cooled, gave the following" results: Yield moooolba, tensile strength 222000, elongation 12%. V

Ha ving thus described my invention what I claim as new and desire to secure by Letters Patent is:

.1. A low-carbon, tough, and readily workable commercial. steel containing between .40 and .60 chromium, between .50 and .80 manganese and with tungsten between 1% and 1.50% added thereto to preserve the strength of the steel at high temperatures.

2. A steel containing as thcessential ingredients other than iron, carbon from low to medium content, chromium 43%, tungsten 1.3% and manganese not exceeding 3. A steel containing as the essential ingredients other than iron, carbon from low temperatures. For

000, tensile strength 222,000 and elongation 12%,contannng as the essential ingredients other than iron, carbon from low to medium content, chromium .4373, tungsten 1.30%, and manganese .6470.

5. A steel containing as gredients other than iron, carbon from low to medium content, chromium in effective amounts but not more than .60% and tungsten in efi'ective amounts not more than 1.3%, having high't-ensile strength and elastic limit both at atmospheric and'high temperatures. v

6. An article of manufacture adapted to be. subjected to great stresses under widely diiierent temperature conditions composed of a steel containing as the essential eonstituents other than iron, carbon from low to medium content, chromium in effective amount but appreciably less than 1% and tungsten from a fraction of 1% to 2%.

In testimony whereof I hereunto afiix my signature this 18th W. ROBERT SHIMER.

the essential inday of November 1924.-