While “simple” chrome steel is pretty well known as a material for products which require great hardness, such as balls, roller bearings, files, rolls, five-ply safes, stamp shoes, projectiles, etc., and heat-treated chrome-vanadium steels are now extensively used in forged frames and shafts of automobile and other machines, a combination of nickel and chromium gives steels which have been great favorites. With 2 to 3½ per cent of nickel, not over 3 per cent of chromium and ½ per cent of carbon, these steels, when expertly heat-treated, can give “elastic limits” anywhere between 40,000 and 250,000 pounds per square inch, with good freedom from brittleness. They are very largely used for automobile gears, axles, and other parts, for armor plate, for projectiles and for many other purposes.
These alloys are also used for castings.
Chrome-Vanadium Steels
Within a comparatively short time the chrome-vanadium steels have come to be very largely used, often in place of the chrome and nickel-chrome steels. As vanadium is a “deoxidizer,” whereas nickel is not, the chrome-vanadium steels show fewer imperfections than the nickel-chrome steels and they also roll, forge and machine better.
They are used for automobile frames, shafts, for miscellaneous forged and rolled articles and for heat-treated armor plates. Of this comparatively new material about 90,000 tons were made during 1913, according to a recently issued bulletin of the Department of the Interior.
It is impossible, of course, to even begin to impart any adequate conception of the qualities and great importance of the alloy steels for purposes of construction. As has been shown they are special steels for special purposes and their application is wide. Incorporation of the new element in the alloy imparts peculiar and valuable properties: for example, 12 per cent of manganese, great hardness and toughness; 23 per cent of nickel, non-corrosive properties and great strength; chromium, nickel with chromium or chromium with vanadium, strength and high elastic limit (resistance to distortion) as well as great hardening power when desired, this, of course, the usual hardening through quenching from a cherry-red heat.
Very often instead of the single defining element, a combination of two, three or even four of them is used. Such, of course, are rather complicated steels having combinations of properties as might naturally be expected, though very often these resulting properties are not those which are expected. In fact no one can tell in advance what properties any new combination of metals in an alloy will produce and often new proportions of the same constituent metals give entirely different and unique results.
The only certain method of ascertaining what characteristics and properties a new alloy will have is to develop it and in that way find out.
Description of a special and extremely important class of these alloys, the “high-speed steels,” will serve to show how laborious, slow and expensive a process development of new alloys may be and what unlooked-for results are sometimes obtained.