GENERAL SUMMARY OF THE RESULTS OBTAINED BY SIR WILLIAM FAIRBAIRN’S EXPERIMENTS.
| Condition of bar. | Breaking weight of bar in lbs. | Breaking weight per square inch. | Strength, the un- touched bar being unity. | ||
| In lbs. | In tons. | ||||
| 1 | Untouched (black) | 50,346 | 58.628 | 26.173 | 1.000 |
| 3 | Rolled cold | 69,295 | 88.230 | 39.388 | 1.505 |
| 4 | Turned | 47,710 | 60.746 | 27.119 | 1.036 |
| Note.—In the above summary itwill be observed that the effect of consolidationby the process of cold rolling is to increase the tensile powersof resistance from 26.17 tons per square inch, to 39.38 tons, being in theratio of 1:1.5, one-half increase of strength gained by the new process ofcold rolling. | |||||
Extract from the general conclusions arrived at by Professor R. Thurston from experiments.
“The process of cold rolling produces a very marked change in the physical properties of the iron thus treated.
“It increases the tenacity from 25 to 40 per cent., and the resistance to transverse stress from 50 to 80 per cent.
“It elevates the elastic limit under torsional as well as tensile and transverse stresses, from 80 to 125 per cent....
“It gives the iron a smooth bright surface, absolutely free from the scale of black oxide unavoidably left when hot rolled.
“It is made exactly to gauge diameter, and for many purposes requires no further preparation.
“The cold-rolled metal resists stresses much more uniformly than does the untreated metal. Irregularities of resistance exhibited by the latter do not appear in the former; this is more particularly true for transverse stress.
“This treatment of iron produces a very important improvement in uniformity of structure, the cold-rolled iron excelling common iron in density from surface to centre, as well as in its uniformity of strength from outside to the middle of the bar.