| ECONOMICS OF ALLOY STEELS | 49 |
Chrovan Steel
| 98.94 lbs. Steel | @ 8.5¢ = $8.41 |
| 0.90 lb. Chromium | @ 25¢ = 0.23 |
| 0.16 lb. Vanadium | @ $10.00 = 1.60 |
| 100.00 lbs. Alloy | @ 10.24¢ = $10.24 |
|
Chrovanmol Steel |
| Working tensile stress for heat-treated steel | = 63,300 lbs. |
| Ditto untreated (entirely assumed) | = 47,000 lbs. |
| Average= 1/2 (2 X 47,000 + 63,300) | = 52,400 lbs. |
Chrovan Steel
| Working tensile stress for heat-treated steel | = 56,000 lbs. |
| Ditto untreated (entirely assumed) | = 41,500 lbs. |
| Average= 1/3 (2 X 41,500+56,000) | = 46,300 lbs. |
|
and r r' = 1.215 X 0.884 = 1.074
From Figs. 5a and 5b we find that this product corresponds to a simple-span length of about 750 feet and to a main cantilever opening of about 2000 feet; and, as these are excessive, it may be concluded, for bridgework, that there is no advantage in adding molybdenum to chrovan steel. The next economic question to solve is that of the gain involved by increasing the percentage of molybdenum in an alloy of steel. From certain diagrams in "Molybdenum Commercial Steels" the following data for comparison of chromol steel of Classes A and C have been excerpted, the treatment-temperature being 800° F. CLASS A |
| Average analysis, Carb. 0.15, Mang. 0.38, |
| Chrom. 0.72, Moly. 0.28 |
| E. L. = 105,000 lbs., Ult. = 130,000 lbs., Elong. = 20%, Red. = 65%. |