. The Iron and steel magazine. al H^^ ^^^°°° ( (b) 208,000 Reheated to 820° C. and cooled in air 1,052,000 Reheated to 850° C. and cooled in air 13,630,000 Reheated to 870° C, cooled in air, and re- f 11,630,00c at 19 tons. heated again to 850° C. and cooled in air I 2,833,000 at 21 tons. In each case the pieces of metal reheated did not weigh morethan four ounces, the heating was rapidly effected and as soon 398 The Iron and Steel Magazine as the desired temperature v/as reached they were removedfrom the furnace. It is probable that a longer heating atsomewhat lower temperatures would have gi
. The Iron and steel magazine. al H^^ ^^^°°° ( (b) 208,000 Reheated to 820° C. and cooled in air 1,052,000 Reheated to 850° C. and cooled in air 13,630,000 Reheated to 870° C, cooled in air, and re- f 11,630,00c at 19 tons. heated again to 850° C. and cooled in air I 2,833,000 at 21 tons. In each case the pieces of metal reheated did not weigh morethan four ounces, the heating was rapidly effected and as soon 398 The Iron and Steel Magazine as the desired temperature v/as reached they were removedfrom the furnace. It is probable that a longer heating atsomewhat lower temperatures would have given equally goodresults. As the pieces heated were small, and the cooling necessarilycomparatively rapid, the treatment maybe regarded as approach-ing that of oil tempering on large masses. In reviewing the known data received from Mr. Holdenabout this axle, together with the information obtained by ourown testing, the following observations should be noted, viz.: (i) The axle stood twenty years before it finally Fig. 6. Fractured Axle. Magnified i^ by Mr. J. H. D. Jenkins. During this period it had traveled probably 300,000 miles, andhad been subjected to 200,000,000 reversals of stress. (2) The flaw which initiated fracture appears to have beena deep stamp mark, clearly seen in the photograph suppliedby Mr. Jenkins (Fig. 6). (3) The weakness produced initially by this deep impression,in our opinion, eventually led to a fatigue fracture, whichtraveled from the upper to the convex termination of whatcorresponds with the light part shown in the or granular fracture followed through the remainingpart of the mass. Overheated Steel 399 (4) The interence is that had there been no such excessivelydeep stamp impression the axle could not have failed.* (5) According to the fiber stress testing, the normal steel ofrather coarse crystalline structure is relatively weak, but, forall that, it is good material, and calculated to be quite s
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjectiron, bookyear1898
