Classifications Of Steel

: The Working 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 pe
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

axles; rails.

Hard 0.60-0.85 Wrought steel wheels for steam and electric

railway service; locomotive tires; rails;

tools, such as sledges, hammers, pick points,

crowbars, etc.

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.