US1979594A - Manganese - molybdenum - vanadium steel and articles made therefrom - Google Patents

Description

Patented Nov. 6 1934 MANGANESE MOLYBDENUM VANADIUM STEEL AND ARTICLES MADE THERE- FROM Sidney D. Williams, Canton, Ohio, assignor to The Timken Roller Bearing Company, Canton, Ohio, a corporation of Ohio No Drawing. Application October 3, 1931, Serial No. 566,788

3 Claims.

My invention relates to alloy steel particularly to steels adaptable for use at temperatures above 750 F. The principal object of the invention is a low cost alloy steel suitable for use at high 5 temperatures, especially 750 F. to 1,000 F. which is resistant to stresses, which possesses a good degree of ductility and resistance to shock at such high temperatures and which is lower in cost than the austenitic and chromium steels commonly used at high temperatures and which is easily workable and capable of being fabricated into intricate shapes.

The invention consists principally in the alloy steel and articles made therefrom hereinafter described and claimed.

Alloy steels embodying my invention have substantially the following range of ingredients:

Carbon-- 0.01 to 0.50% Manganese 1.0 to 3.0%

Molybdenum 0.01 to 0.50% Vanadium 0.01 150 0.50%

with the usual percentages of silicon, sulphur and phosphorous.

A preferred narrower range of ingredients is as follows:

Alloy steels embodying my invention are particularly suitable for use as boiler tubes. Other uses are condenser tubes, heat exchanger tubes, super-heater tubes, oil still tubes for sweet crude oil, bolts, stay rods, valve parts and other articles requiring high strength at elevated temperatures.

It is recognized that molybdenum steels have long been known; but their use has been confined to low temperatures, that is room or atmospheric temperatures and for the most part to case hardened articles. These steels having the foregoing composition have shown them to possess unusual strength at elevated temperatures, to have a high proportional limit and excellent load carrying capacity and, in addition, to have a reasonable amount of ductility and resistance to shock. The said steels also have a very high creep strength as is to be expected from their high short time proportional limit value.

The results of tests of a typical steel embodying my invention are as follows:

(Cl. l5-1) Physical properties at 75 F.

Tensile strength Proportional Percent Percent Brinen Izod elong. red. hardimp. lbs. per sq.m. limit #/sq. in. area Hess it.lbs

Tensile properties at 800 and 900 F.

S rellg Temp. Tensilestrcngth Proportional gfgg z lper- F. lbs. per sq. in. limit #/sq.in.- 11 area: 006101201631 hl' a The heat treatments consist of annealing, normalizing and water quenching, the last two treatments being followed by a 1100 F. draw.

The quality of said alloy steels as hereinbefore brought out make them especially satisfactory for use as boiler tubes and in other articles above mentioned. The steei also has a good degree of resistance to oxidation.

The articles provided by this invention thus are made from steels which contain manganese, molybdenum and vanadium as characterizing elements.

The steels may contain also'impurities and elements incidental'to manufacture and in amounts which do not adversely affect the creep resistance which characterizes the invention, and

for this reason the remainder of the alloy (apart from carbon and the characterizing elements) may be considered as being efiectively iron.

What I claim is:

1. An article, such as a boiler tube or the like, for use at elevated temperatures, e. g., from 750 to 1000 F., characterized by high creep strength at such temperatures and by being formed from a steel alloy containing from about 0.01 to 0.5 per cent-of carbon, about 1 to 3 per cent of manganese, about 0.01 to 0.5 per cent of molybdenum,

about 0.01 to 0.5 per cent of vanadium, not more thanabout 0.5 per cent of silicon, and the remainder effectively iron.

2. An article, such as a boiler tube or the like,

per cent of carbon, about 1 to 3 per cent of manganese, about 0.01 to 0.5 per cent of molybdenum, about 0.01 to 0.5 per cent of vanadium, not more than about 0.5 per cent of silicon, and the remainder effectively iron.

SIDNEY D. WILLIAMS.