Classifications Of Steel
Category: COMPOSITION AND PROPERTIES OF STEEL
Among makers and sellers, carbon tool-steels are classed by grade
and temper. The word grade is qualified by many adjectives of
more or less cryptic meaning, but in general they aim to denote
the process and care with which the steel is made.
Temper of a steel refers to the carbon content. This should preferably
be noted by points, as just explained; but unfortunately, a 53-point
steel (containing 0.53 per cent carbon) may locally be called something
like No. 3 temper.
A widely used method of classifying steels was originated by the
Society of Automotive Engineers. Each specification is represented
by a number of 4 digits, the first figure indicating the class, the
second figure the approximate percentage of predominant alloying
element, and the last two the average carbon content in points.
Plain carbon steels are class 1, nickel steels are class 2,
nickel-chromium steels are class 3, chromium steels are class 5,
chromium-vanadium steels are class 6, and silico-manganese steels
are class 9. Thus by this system, steel 2340 would be a 3 per cent
nickel steel with 0.40 per cent carbon; or steel 1025 would be a
0.25 plain carbon steel.
Steel makers have no uniform classification for the various kinds
of steel or steels used for different purposes. The following list
shows the names used by some of the well-known makers:
Air-hardening steel Chrome-vanadium steel
Alloy steel Circular saw plates
Automobile steel Coal auger steel
Awl steel Coal mining pick or cutter steel
Axe and hatchet steel Coal wedge steel
Band knife steel Cone steel
Band saw steel Crucible cast steel
Butcher saw steel Crucible machinery steel
Chisel steel Cutlery steel
Chrome-nickel steel Drawing die steel (Wortle)
Drill rod steel Patent, bush or hammer steel
Facing and welding steel Pick steel
Fork steel Pivot steel
Gin saw steel Plane bit steel
Granite wedge steel Quarry steel
Gun barrel steel Razor steel
Hack saw steel Roll turning steel
High-speed tool steel Saw steel
Hot-rolled sheet steel Scythe steel
Lathe spindle steel Shear knife steel
Lawn mower knife steel Silico-manganese steel
Machine knife steel Spindle steel
Magnet steel Spring steel
Mining drill steel Tool holder steel
Nail die shapes Vanadium tool steel
Nickel-chrome steel Vanadium-chrome steel
Paper knife steel Wortle steel
Passing to the tonnage specifications, the following table from
Tiemann's excellent pocket book on Iron and Steel, will give
an approximate idea of the ordinary designations now in use:
Grades carbon range Common uses
Extra soft 0.08-0.18 Pipe, chain and other welding purposes;
(dead soft) case-hardening purposes; rivets; pressing
and stamping purposes.
Structural (soft) 0.15-0.25 Structural plates, shapes and bars for
(medium) bridges, buildings, cars, locomotives;
boiler (flange) steel; drop forgings; bolts.
Medium 0.20-0.35 Structural purposes (ships); shafting;
automobile parts; drop forgings.
Medium hard 0.35-0.60 Locomotive and similar large forgings; car
Hard 0.60-0.85 Wrought steel wheels for steam and electric
railway service; locomotive tires; rails;
tools, such as sledges, hammers, pick points,
Spring 0.85-1.05 Automobile and other vehicle springs; tools,
such as hot and cold chisels, rock drills
and shear blades.
Spring 0.90-1.15 Railway springs; general machine shop tools.
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