f treatment.

Steel makers have various ways of designating carbon steels for
different purposes. Some of these systems involve the use of numbers,
that of the Latrobe Steel Company being given herewith. It will
be noted that the numbers are based on 20 points of carbon per
unit. The names given the different tempers are also of interest.
Other makers use different numbers.

The temper list follows:

LATROBE TEMPER LIST OF CARBON TOOL STEELS
No. 3 temper 0.60 to 0.69 per cent carbon
No. 3-1/2 temper 0.70 to 0.79 per cent carbon
No. 4 temper 0.80 to 0.89 per cent carbon
No. 4-1/2 temper 0.90 to 0.99 pet cent carbon
No. 5 temper 1.00 to 1.09 per cent carbon
No. 5-1/2 temper 1.10 to 1.19 per cent carbon
No. 6 temper 1.20 to 1.29 per cent carbon
No. 6-1/2 temper 1.30 to 1.39 per cent carbon
No. 7 temper 1.40 to 1.49 per cent carbon

USES OF THE VARIOUS TEMPERS OF CARBON TOOL STEEL

DIE TEMPER.--No. 3: All kinds of dies for deep stamping, pressing
and drop forgings. Mining drills to harden only. Easily weldable.

SMITHS' TOOL TEMPER.--No. 3-1/2: Large punches, minting and rivet
dies, nailmakers' tools, hammers, hot and cold sets, snaps and
boilermakers' tools, various smiths' tools, large shear blades,
double-handed chisels, caulking tools, heading dies, masons' tools
and tools for general welding purposes.

SHEAR BLADE TEMPER.--No. 4: Punches, large taps, screwing dies,
shear blades, table cutlery, circular and long saws, heading dies.
Weldable.

GENERAL PURPOSE TEMPER.--No. 4-1/2: Taps, small punches, screwing
dies, sawwebs, needles, etc., and for all general purposes. Weldable.

AXE TEMPER.--No. 5: Axes, chisels, small taps, miners' drills and
jumpers to harden and temper, plane irons. Weldable with care.

CUTLERY TEMPER.--No. 5-1/2: Large milling cutters, reamers, pocket
cutlery, wood tools, short saws, granite drills, paper and tobacco
knives. Weldable with very great care.

TOOL TEMPER.--No. 6: Turning, planing, slotting, and shaping tools,
twist drills, mill picks, scythes, circular cutters, engravers'
tools, surgical cutlery, circular saws for cutting metals, bevel
and other sections for turret lathes. Not weldable.

HARD TOOL TEMPER.--No. 6-1/2: Small twist drills, razors, small
and intricate engravers' tools, surgical instruments, knives. Not
weldable.

RAZOR TEMPER.--No. 7: Razors, barrel boring bits, special lathe
tools for turning chilled rolls. Not w