December, 1939, Canadian Aviation
Aviation provides new and expanding markets for stainless steel, it is reported by the Iron Alloys Committee of the U.S. Engineering Foundation research agency of the national engineering societies. The ease with which stainless steel is welded enables airplane manufacturers to do away with rivets which, although very small, have been proved by tests to make an appreciable difference in air resistance at the high speeds current in modern flying, according to the report.
Numerous parts of planes, including complete wings, tails and fuselages, have been made with stainless steel and successfully used. Several types of European military planes use stainless steel for standardized parts. This trend is gradually extending to the field of small and inexpensive private planes, one builder of such machines specifying stainless steel for rudders, stabilizers, elevators and fuel tanks, it is reported.
Although stainless steel is heavier than some of the light alloys now used, it compensates for this disadvantage in airplane construction by being stronger, which, in conjunction with its corrosion-resistance, enables it to be safely used in many thin sections, bringing the weight of the completed structure down to an equal basis.
Outgrowth of Train Use
The gradually increasing use of stainless steel in planes, and the forecast of a much greater use, can be logically deduced from the successful application and the highly satisfactory performance of the material in high speed, lightweight railway equipment. While certain factors are important in the air which are irrelevant in surface transportation, the report continues, there are also many points of similarity in the desired ends in both cases.
During the past five years, the production of stainless steel has become more and more complex. Its production at present often includes the addition of manganese, titanium, columbium, molybdenum, silicon, sulphur, selenium and copper. The report shows that in a few instances there even has been a radical change in the proportion of chromium and nickel, the two elements which, with iron, are the common constituents of stainless steel. These variations are the result of attempts to adjust the properties of the metal to give the best results in the various functions which it performs.
Molybdenum has been found to be increasingly useful in the manufacture of stainless steel. Greater amounts of this metal are being added, usually with an accompanying drop in the percentage of chromium and nickel. The molybdenum improves the steel’s resistance to mineral and organic acid attack, and enables the steel to remain hard when reheated.
This article originally appeared in the December, 1939 edition of Canadian Aviation magazine.