CARBON STEELS FOR DIFFERENT TOOLS

All users of tool steels should carefully study the different qualities of the steels they handle. Different uses requires different kinds of steel for best results, and for the purpose of designating different steels some makers have adopted the two terms "temper," and "quality," to distinguish between them.

In this case temper refers to the amount of carbon which is combined with the iron to make the metal into a steel. The quality means the absence of phosphorous, sulphur and other impurities, these depending on the ores and the methods of 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:

No. 3temper 0.60 to 0.69 per cent carbon
No. 3½temper 0.70 to 0.79 per cent carbon
No. 4temper 0.80 to 0.89 per cent carbon
No. 4½temper 0.90 to 0.99 pet cent carbon
No. 5temper 1.00 to 1.09 per cent carbon
No. 5½temper 1.10 to 1.19 per cent carbon
No. 6temper 1.20 to 1.29 per cent carbon
No. 6½temper 1.30 to 1.39 per cent carbon
No. 7temper 1.40 to 1.49 per cent carbon