The bars were nicked six times at intervals of about ¾-inch and then heated so that the ends were scintillating, ready to pass into the granular condition, and the heat was so regulated as to have each piece less hot than the piece next nearer to the end, the last piece, No. 6, being black and as nearly cold as possible.
It is manifest that this operation is subject to the error of accidentally getting No. 2, for instance, hotter than No. 1, and so on, so that perfect regularity is not to be expected; to obtain a true rule of expansion it would be necessary to make hundreds of such experiments and use the mean of all.
It will be noticed that No. 4 is abnormal in the ingot series, and that the No. 6 piece of No. 4 is abnormal in being lighter than the ingot; probably this No. 6 of No. 4 was hot when it was intended to be cold. Also No. 2 of ingot No. 3 is lighter than its No. 1, showing another irregularity in heating.
Taking the whole list of No. 1 pieces, they are all lighter than their respective No. 6 pieces; the differences of sp. gr. 6-1 are progressive, being only .025 for the No. 3 ingot and .135 for the No. 12 ingot. This shows clearly that expansion due to a given difference in temperature is much greater in high steel than in low steel.
This clears away the mystery of the so-called treachery of high steel, its tendency to crack when hardened. There is no treachery about it; it is very sensitive to temperature, and it must be treated accordingly.
A few examples will now be given to show the changes of tensile strength, ductility, etc., that may be had by differences of carbon, and by differences of treatment, annealing, hardening, and tempering.
TABLE II
| Character of Steel. | O. H. | Crucible Sheet | O. H. | O. H. | O. H. | Crucible Eye-bar, 2″ × 1″. | Crucible Eye-bar, 2″ × 1″. | Crucible Eye-bar, 2″ × 1″. | Crucible ½-in. Drawn Wire. | |
|---|---|---|---|---|---|---|---|---|---|---|
| Carbon | .09 to .12 | .435 | .50 | .60 | .70 | .96 | 1.35 | 1.40 | 1.15 | |
| Silicon | .008 | .014 | .025 | .156 | < .02 | |||||
| Phosphorus | .007 | .050 | .016 | .008 | < .02 | |||||
| Sulphur | .026 | .028 | .028 | .015 | trace | |||||
| Manganese | .055 | .204 | .325 | .24 | < .30 | |||||
| Tensile strength, | ||||||||||
| lbs. per sq. in. | 46800 | 73142 | 84220 | 108800 | 117400 | 124800 | 100733 | 117710 | 141500 | |
| Elastic limit | 30900 | 63560 | 71500 | 69980 | 65000 | 85087 | 69850 | 92420 | ||
| Elongation |  | in 2 | in 1 | 25% | 14.5% | 11.5% | 4.75% | .5% | 7.28 at | 2% |
| in. 41% | in. 42% | 2.85 in 2½ | ||||||||
| Reduction of area | 75.85% | 62.3% | 29.91% | 13.55% | 8.59% | 13.03% | 2.42% | |||
| Fracture |  | |||||||||
| broke | ||||||||||
| silky | in neck | broke | broke | |||||||
| ½ | slight | in head | in | |||||||
| cup | flaw, | close | grip | |||||||
| fine | grain | |||||||||
| grain | ||||||||||
| O. H. is the abbreviation for open hearth. | ||||||||||
| Second column is mean of 24 analyses and 24 tests of boiler-sheets. | ||||||||||
TABLE III
| Cold-drawn Wire, ½-inch Diam. | Tensile Strength, lbs. per sq. in. | Elastic Limit, lbs. per sq. in. | Elongation. | Reduction of Area, per ct. | |
|---|---|---|---|---|---|
| In 3 in. | Per cent. | ||||
| Cold-drawn, broke in grip | 141,500 | 92,400 | .06 | 2.00 | 2.42 |
| Same bar drawn black | 138.400 | 114,700 | .18 | 6.00 | 12.45 |
| “ “ annealed | 98,410 | 68,110 | .30 | 10.00 | 11.69 |
| “ “ hardened and then drawn black | 248,700 | 152,800 | .25 | 8.33 | 19.7 |