US2021783A - Alloy steel and articles made therefrom - Google Patents

Description

Patented Nov. 19, 1935 UNITED STATES PATENT OFFICE ALLOY STEEL AND ARTICLES MADE TnEnEFnoM trustee No Drawing. Application November 20, 1931, Serial No. 576,430

5 Claims.

Our invention relates to alloy steels which are.

required to resist oxidation at temperatures up to 1200? F. and to possess good load carrying ability at such high temperatures and-which are considerably lower in cost than the austenitic steels and chromium steels used at such temperatures.

The principal object of the invention is an alloy steel capable of resisting oxidation at temperatures up to 1000 F., possessing good load carrying ability at such temperatures and having other desirable physical qualities at such temperatures.

The invention consists principally in a chromium-tungsten-silicon alloy steel having substantiallythe following composition:

, Per cent Carbon 0.01 to 0.60 Manganese 0.20 to 1.0 siumn 1,0 t 3,0 Chromium 1.5 to 3.0 Tung 0.25 to 1.0

with or without vanadium from 0.01 to 50%. The invention further consists in the alloy steel and articles made therefrom hereinafter described and claimed.

Our alloy is particularly adapted for use in grate bars, stoker parts, soot blowers, carburizing boxes either as sheet boxes or as castings, furnace parts, industrial valve parts for high temperature service, casting and forgings. The range of ingredients of alloy steels embodying our invention are substantially as follows:

Vanadium in amounts-from 0.01 to 0.50% may be added to any said steels. The tungsten content is always substantially less than the chromium content.

Actual tests of numerous specimens of steel within the above ranges have been made as to their proportional limit values at high temperatures, creep strength, ductility, tensile strength and load carrying capacity and resistance to oxidation; and the results show that said steels have very desirable properties and that such properties are far superior to what would heretofore have been expected in any chromiumtungsten-silicon alloy.

The following are the results of tests of a typical steel embodying our invention comprising: .50% C, 375% Mn, 2.41% Si, .55% W, 2.78%

Physical properties at 75 F.

Tensile strength lbs. per sq. in.

Brinell hardness Percent elong. 2!!

Percent red.

Izod 1m. Pact Physical properties at 1000 F.

Creep strength 1 1%per 100,000 hrs.

Tensile strength lbs. per sq. in.

Percent elong. 2!!

Percent red.

1000 F. 1100 F. 1200 F.

The qualities of said alloy steel as hereinbeiore brought out make such steel particularly desirable for use in the articles mentioned and in all articles requiring excellent resistance to oxidation and good strength at high temperatures.

What we claim is:

1. An article for use at high temperatures, such as a grate bar, stoker parts, carburizing boxes, valve parts, and furnace parts, such as boiler tubes or the like, the article being characterized by good resistance to oxidation at temperatures of 1000 F. and higher, and by substantial and maintained creep strength under continuous exposure to operating stress at temperatures in excess of 750 F., and being formed from steel con taining from about 0.01 to 0.6 per cent of carbon,

more than 1.5 to about 3 per cent of chromium,

about 0.2 to 1 per cent oi manganese, more than 1 to about 3 per cent of silicon, about 0.25 to 1 per cent of tungsten, and the remainder substantially iron.

2. An article for use at high temperatures, such as grate bar, stoker parts, carburizing boxes, valve parts, and furnace parts, such as boiler tubes or the like, the article being characterized by good resistance to oxidation at temperatures of 1000 F. and higher, and by substantial andmaintained creep strength under continuous exposure to operating stress at temperatures in excess of 750 F., and being formed from steel containing from about 0.4 to 0.5 per cent of carbon, about 2.5 to 3 per cent of chromium, about 0.4 to 0.6 per cent of manganese, about 2.5 to 3 per cent of silicon, about 0.5 to 0.75 per cent of tungsten, and the remainder substantially iron.

3. An article for use at high temperatures, such as a grate bar, stoker parts, carburizing boxes, valve parts, and furnace parts, such as boiler tubes or the like, the article being characterized by good resistance to oxidation at temperatures of 1000 F. and higher, and by substantial and maintained creep strength under continuous exposure to operating stress at temperatures in excess of 750 F., and being formed from steel containing from about 0.01 to 0.6 per cent of carbon, more than 1.5 to about 3.0 per cent of chromium, about 0.2 to 1 per cent of manganese, more than 1 to about 3 per cent of silicon, about 0.25 to 1 per cent of tungsten, about 0.01to 0.5 per cent of vanadium, and the remainder substantially iron. 1

4. An article for use at high temperatures, such as a. grate bar, stoker parts, carburizing boxes, valve parts, and furnace parts, such as boiler tubes or the like, thearticle being characterized by good resistance to oxidation at 5 'cent of vanadium, and the remainder substan- 15 tially iron. q

5. An article for use at high temperatures, such as a grate bar, stoker parts, carburizing boxes, valve parts, and furnace parts, such as boiler tubes or the like, the article being characterized 20 by good resistance to oxidation at temperatures of 1000 F. and higher, and by substantial and maintained creep strength under continuous exposure to operating stress at temperatures in excess of 750 and being formed from steel con- 25 taining about 0.5 per cent of carbon, about 2.78 per cent of chromium, about 0.75 per cent of manganese, about 2.41 per cent of silicon, about 0.55 per cent of tungsten, and the remainder sub- I stantially iron. Y 30 WALTER G. HILDORF.

ALBERT E. WHITE. CLAUDE L. CLARK.