. The Iron and steel magazine. duringthe bending was mainly confined to the massive ferrite envelopesand sheets. At first they appeared to sink below the surface,and eventually developed into actual fissures or incipient cracks; * It may here be mentioned that, in the experience of one of theauthors, this weakness and eventual fracture in axles is not by anymeans uncommon as the result of a deep stamp indentation. Such in-dentations are the exact equivalents of flaws, but instead of being acci-dental are deliberately x^roduced. 400 The Iron and Steel Magazine an observation confirmed by Mr. Je
. The Iron and steel magazine. duringthe bending was mainly confined to the massive ferrite envelopesand sheets. At first they appeared to sink below the surface,and eventually developed into actual fissures or incipient cracks; * It may here be mentioned that, in the experience of one of theauthors, this weakness and eventual fracture in axles is not by anymeans uncommon as the result of a deep stamp indentation. Such in-dentations are the exact equivalents of flaws, but instead of being acci-dental are deliberately x^roduced. 400 The Iron and Steel Magazine an observation confirmed by Mr. Jenkins in the case of thebroken axle. (4) The researches of Professor Ewing, Messrs. Humfrey,A. E. Seat on * and A. Jude have proved that fracture of steel,when under the influence of long-continued fatigue or undersudden shock, is initiated in the free ferrite, and generally travelscontinuously as far as possible along a track in which there is thegreatest amount of that constituent, in fact along the line ofleast Fig. 7. Portion of Broken Axle; central part of one of the large supplied by Mr. Jenkins. Magnified 150 diameters. (5) That in pure or nearly pure commercial carbon steelsthe ferrite has a yield point of probably not more than 8 to 12tons per square inch, whereas the other constituent, pearlite,docs not sensibly yield until a tension of about twice theseamounts is reached, excepting when its structure is composedof broad sheets of ferrite and carbide of iron, for in such case the * Impact Tests on Wrought Steels of Commerce. Proceedings ofthe Institution of Mechanical Engineers, 1904, p. 1135. Overheated Steel 401 ferrite behaves as if it were massive, and the yield point isnecessarily nuioh lower. (6) The weakness of a steel under stress in any givendirection depends on the manner in which the ferrite and pearliteare arranged with relation to the stresses applied. For in-stance, in large forgings it not infrequently happens that theferrite a
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Keywords: ., bo, bookcentury1800, bookdecade1890, booksubjectiron, bookyear1898
