No. 1 has been struck; it is then turned up to position No. 2 and knocked into shape No. 3. The rapid hammering of a bar, turning it a little at a time, must burst it if the blows are heavy enough to deform the whole section. Heavy radial rolling produces the same results.
The concluding pages of this chapter will be devoted to a few examples showing by tests the effects of heat and work upon specific-gravity, tensile strength, elasticity, and ductility; they are not to be taken as fixing exact limits in any case; they are given merely to illustrate the truth of the general properties stated, and to show the wide ranges of strength that are attainable by varying carbon and work.
TABLE I
| Character of Steel. | Ingot Numbers. | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | |
| Carbon | .302 | .490 | .529 | .649 | .801 | .841 | .867 | .871 | .955 | 1.005 | 1.058 | 1.079 |
| Silicon | .019 | .034 | .043 | .039 | .029 | .039 | .057 | .053 | .059 | .088 | .120 | .039 |
| Phosphorus | .047 | .005 | .047 | .030 | .035 | .024 | .014 | .024 | .070 | .034 | .064 | .044 |
| Sulphur | .018 | .016 | .018 | .012 | .016 | .010 | .018 | .012 | .016 | .012 | .006 | .004 |
| Sp. gr. ingots. | 7.855 | 7.836 | 7.841 | 7.829 | 7.838 | 7.824 | 7.819 | 7.818 | 7.813 | 7.807 | 7.808 | 7.805 |
| Sp. gr. bars, | ||||||||||||
| burned, 1 | 7.818 | 7.791 | 7.789 | 7.752 | 7.744 | 7.690 | ||||||
| 2 | 7.814 | 7.811 | 7.784 | 7.755 | 7.749 | 7.741 | ||||||
| 3 | 7.823 | 7.830 | 7.780 | 7.758 | 7.755 | 7.769 | ||||||
| 4 | 7.826 | 7.849 | 7.808 | 7.773 | 7.789 | 7.798 | ||||||
| 5 | 7.881 | 7.806 | 7.812 | 7.790 | 7.812 | 7.811 | ||||||
| cold, 6 | 7.844 | 7.824 | 7.829 | 7.825 | 7.826 | 7.825 | ||||||
| Diff. 6-1 | .025 | .034 | .040 | .073 | .082 | .135 | ||||||
| Mean diff. of carbon | .071 | |||||||||||
The twelve ingots treated here were first selected by ocular inspection for carbons; the carbons were then determined by combustion analyses.
It will be seen that the inspection was correct, and that the mean difference in carbon between consecutive numbers is .007. Between Nos. 7 and 8 there is a difference of only .004; when the analyst discovered this, he asked for a reinspection, not giving any reason for his request. The inspectors made new fractures, examined the ingots carefully in good light, and reported that they erred the first time, that both ingots belonged in the same temper number, but that if there were any difference No. 8 was the harder. It is not claimed that a difference of .004 is really observable.
The contents of silicon, phosphorus, and sulphur show clearly that the controlling element is carbon. This experiment has been repeated a number of times, and always with the same result, showing that there is no uncertainty in this method of separating tempers.
Parts of these ingots were reduced to ¾-inch round bars. The specific gravities of the ingots were taken, showing generally a reduction of sp. gr. for an increase of carbon. No. 3 and 5 are anomalous; an explanation of this could doubtless have been found if a careful investigation had been made, but there was no re-examination.
The sp. gr. No. 6 are of the ¾-inch bars as they came from the rolls; they are all heavier than the ingots except No. 4, and they are of nearly uniform sp. gr.; this is due doubtless to the fact that the higher carbon steels are so much harder than the low-carbon steels that it required much more work to reduce them to the bars, and as hot-working increases density, the densities of the higher carbons were increased more than those of the lower.