| Carbon | 0.95 to 1.05 per cent |
| Silicon | 0.20 to 0.35 per cent |
| Manganese | 0.30 to 0.45 per cent |
| Chromium | 0.35 to 0.45 per cent |
| Sulphur and phosphorus not to exceed | 0.025 per cent |
For the larger sizes a typical analysis is:
| Carbon | 1.02 per cent |
| Silicon | 0.21 per cent |
| Manganese | 0.40 per cent |
| Chromium | 0.65 per cent |
| Sulphur | 0.026 per cent |
| Phosphorus | 0.014 per cent |
Balls 5/8 in. and below are formed cold on upsetting or heading machines, the stock use is as follows:
| Diameter of ball, inch | Diameter of stock inch | Diameter of ball, inch | Diameter of stock inch |
|---|---|---|---|
| 1/8 | 0.100 | 5/16 | 0.235 |
| 5/32 | 0.120 | 3/8 | 0.275 |
| 3/16 | 0.145 | 7/16 | 0.320 |
| 7/32 | 0.170 | 1/2 | 0.365 |
| 1/4 | 0.190 | 9/16 | 0.395 |
| 9/32 | 0.220 | 5/8 | 0.440 |
For larger balls the blanks are hot-forged from straight bars. They are usually forged in multiples of four under a spring hammer and then separated by a suitable punching or shearing die in a press adjoining the hammer. The dimensions are:
| Diameter of ball, inch | Diameter of die, inch | Diameter of stock, inch |
|---|---|---|
| 3/4 | 0.775 | 0.625 |
| 7/8 | 0.905 | 0.729 |
| 1 | 1.035 | 0.823 |
Before hardening, the balls are annealed to relieve the stresses of forging and grinding, this being done by passing them through a revolving retort made of nichrome or other heat-resisting substance. The annealing temperature is 1,300°F.
The hardening temperature is from 1,425 to 1,475°F. according to size and composition of steel. Small balls, 5/16 and under, are quenched in oil, the larger sizes in water. In some special cases brine is used. Quenching small balls in water is too great a shock as the small volume is cooled clear through almost instantly. The larger balls have metal enough to cool more slowly.
Balls which are cooled in either water or brine are boiled in water for 2 hr. to relieve internal stresses, after which the balls are finished by dry-grinding and oil-grinding.