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The horizontal fissure is one that lies imbedded in the rail in a horizontal position parallel with the top of the head and generally from one

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Fig. 2. SAMPLE OF HORIZONTAL FISSURE, LOOKING Down On Top OF HEAD.

half to three-fourth inch below it. An illustration of it is given in Fig. 2. The simple horizontal fissure is not, however, frequent in rail that have broken in the track, because before the point of breakage is reached, a transverse crack branches off from the horizontal one, finally breaking as a compound fissure, as illustrated in Fig. 3. These two kinds of fis

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sure are really only one type and start from longitudinal streaks (mostly non-metallic inclusions) in the interior of the head. The fissure first grows laterally and longitudinally from the streak and after awhile a branch develops up or down from the horizontal crack, or perhaps up at one end and down at the other, finally resulting in a fracture of the rail. These fissures occur mostly in the upper rail of the ingot and are closely allied to the type of failure known as "split head." This latter is perhaps a fissure, but it is a type of failure that has been long known as "piped" rail and it is well to keep it in a separate classification,

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The Cause of Transverse Fissures Our present information indicates fairly definitely that simple transverse fissures develop from shrinkage checks in the interior of the rail head, or from a shattered condition inside. The evidence that transverse fissures have their origin in shattered steel in the interior has been a matter of gradual growth. In the early investigations it had been noted that simple transverse fissures always developed from a granular nucleus; also, that although the metal was generally satisfactory from a chemical standpoint, it was of low ductility in the interior of the head, without, however, the reason being clear for the low ductility while the other parts of the rail section showed good physical properties.

The papers by Wickhorst in 1915 "Study of a Rail with Internal Fissures," and "Internal Fissures in New Rails," and also later papers, called attention to the presence of cracks in the interior of the rail head. The method of examination was to etch sections with copper chloride solution and the polish the etched section, but this method was comparatively cumbersome and only partly effective. It remained for the admirable work of F. M. Waring and K. E. Hoffammann at the Altoona Laboratory, published in 1919, to use the method of deep etching, which so simply and effectively discloses the shattered condition. There was still some question as to whether the cracks disclosed were not produced in the etching, but the work of Rawdon at the Bureau of Standards showed that the cracks are pre-existent; that is, they exist previous to the etching. Rawdon also showed that the walls of the cracks are apt to be in such intimate contact that the cracks may not be observed even with the usual microscopic examination, but need strong etching or other special examination to make them visible.

More recent work has shown that the shattered condition is con-
fined to the interior of the rail and does not extend fully to the end of
the rail as hot-sawed at the mill, but terminates about one-half inch short
of the end. This indicates that the shattering was not in the hot rail bar
as rolled but is a condition of shrinkage checking developed in the cooling.
Further work on the subject should not be directed toward determining
the conditions under which the shattering occurs and also the conditions
necessary to prevent its occurrence.

The Cause of Horizontal and Compound Fissures
As already mentioned above, the cause of the longitudinal fissures,
usually with transverse branches, otherwise called compound or coalescent
fissures, is of a different nature from the cause of the simple transverse
fissures

. The longitudinal fissure spreads out from a longitudinal streak
which seems generally to be a thread of non-metallic inclusion in the
interior of the head. Tablations, notably those by Dr. Dudley, have shown
that this type of failure occurs mostly in the upper rail of the ingot.
It is closely related to the split head and probably the remedy is the
some for both; namely, a clean, well deoxidized steel with a liberal top
discard or with a sink-head ingot.

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Bibliography The literature on the subject of fissures in rails starts with J. E. Howard's report on the Manchester wreck on the Lehigh Valley in 1911, when, as above stated, the transverse fissure first came prominently to public attention. While not exhaustive, it is believed that the bibliography and abstracts given below are a fairly full representation of the literature on the subject. The bibliography from 1911 to 1915, inclusive, is taken from the former report and is extended to include the year 1920, which extension was largely prepared by John B. Emerson. It includes also some references to the literature of “snow-flakes” found in gun and other forgings, which seems to be a closely related subject.

INTERNAL FISSURES IN RAILS

Bibliography 1911.

"Interstate Commerce Commission Investigation of Lehigh Valley Accident at Manchester, N. Y." Report of the Chief Inspector of Safety Appliances of a serious accident on August 25, 1911, embodying a report by James E. Howard. The rail which caused the accident showed internal transverse fissures and other defects. The formation and development of the internal fissures is explained as "due to the use of hard steel and subjecting it to high wheel pressures” under repeated alternations of stress.

"The Broken Lehigh Valley Rail." Iron Age, Vol. 88, p. 800, October 12, 1911. From Mr. Job's testimony in coroner's inquiry concerning Lehigh Valley wreck near Manchester, N. Y., on August 25, 1911.

“Rail Failure-Lehigh Valley Wreck.” Iron Trade Review, Vol. 49, p. 1108, December 21, 1911. From coroner's report of Lehigh Valley wreck at Manchester, N. Y., August 25, 1911, with references to reports by Touceda, Job and Howard. Touceda found high manganese, which may have produced "cold shortness under shock." Job attributed defects to faulty mill practice. Howard blamed heavy loads and hard steel. 1912.

"Limit of Endurance of Steel Rails Reached?" Iron Trade Review, Vol. 50, p. 353, February 8, 1912. Mr. Howard's report on Manchester wreck, with illustrations of rail.

"The Broken Lehigh Valley Rail." Railway Age Gazette, Vol. 52, p. 280, February 16, 1912. An extended and copiously illustrated abstract of a report made by J. E. Howard for the Interstate Commerce Commission, concerning accident to Lehigh Valley train at Manchester, N. Y., on August 25, 1911. An editorial on this paper occurs in the same number, p. 267.

"Wheel Loads and Transverse Fissures in Rails." By "Mechanical Engineer." Railway Age Gazette, Vol. 52, p. 468, March 15, 1912. Discussion of Mr. Howard's report on the Lehigh Valley rail.

"Broken Rail on the New Haven." Railway Age Gazette, Vol. 52, p. 1012, May 3, 1912. On February 11, 1912, the Federal Express on the New York, New Haven & Hartford Railroad was derailed by a broken rail that showed an internal transverse fissure. Some results are given of the examination of the rail by the railroad.

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"Some Defective Rails and How to Avoid Them.” By Robert Job. Iron Trade Review, Vol. 51, p. 504, September 12, 1912. From paper before the International Society for Testing Materials. Illustrations are given, including internal fissures, which are attributed to defective mill practice, the details of which are not otherwise discussed.

"Types of Defective Rails and Some Methods Used in Detecting Them." By Robert Job. Railway Age Gazette, Vol. 53, p. 954, November 15, 1912. Paper presented at Sixth Congress of the International Association for Testing Materials, New York, September, 1912. Among other types of rail failures Mr. Job presented illustrations of transverse and compound internal fissures. Concerning them he remarked that "thorough study proved beyond question that the composition of the steel in its ordinary elements was not the cause of the failure, and also that the conditions of service were not the prime cause."

"That Broken Rail on the Lehigh Valley Railroad." Railway and Engineering Review, Vol. 51, p. 1023, November 25, 1912. Editorial comment dissenting from views expressed in Interstate Commerce Commission report. 1913.

“Investigation of Silvery Oval Spots, sometimes called 'Transverse or Internal Fissures' in Rail Heads." By W., C. Cushing, Proceedings, American Railway Engineering Association, Vol. 14, 1913, p. 413. Results of the examination of some transverse fissure rails by C. D. Young of the Altoona Laboratory of the Pennsylvania Railroad. Slag was found in the fractures and the suggestion is made that this may have started an internal fracture, which developed in service until a broken rail resulted.

"Interstate Commerce Commission Investigation of Louisville & Nashville Accident near Hay's Mill, Ala." Report by Chief Inspector of Safety Appliances, dated August 15, 1913, of accident on October 1, 1912, embodying report by J. E. Howard. "The formation and successive development of these transverse fissures, as a matter of opinion, was the direct result of overstraining loads, combined alternate repeated bending stresses and intense wheel contact stresses.”

"Analysis of a Broken Rail." Railway Age Gazette, Vol. 55. p. 623, October 3, 1913. Extract from a report by J. E. Howard on rail that caused a derailment on the Louisville & Nashville Railroad near Hay's Mill, Ala., October 1, 1912. Examination showed the rail to contain a number of transverse fissures. The rail was found to be high in carbon, but of uniform chemical composition. The explanation is given that the fissures were due to repeated alternations of combined bending stresses and intense wheel contact stresses, and the origin of the fissure in the interior is explained as due to the cold rolling effect of the wheels putting the metal at the running surface in compression and thus offsetting tensile stresses near the running surfaces, 1914.

"Interstate Commerce Commission Investigation of Southern Railwas Accident near Oyama, N. C.” Report by Chief Inspector of Safety Appliances, dated January 7, 1914, of accident on March 31, 1913, embodying report by J. E. Howard. The same explanation of the formation of fissures is given as in the previous cases.

"Internal Transverse Cracks and Fissures in Rails." By Robert Job. Railway Age Gazette, Vol. 56, p. 266, February 6, 1914. Illustrations are given of rails showing transverse fissures, including some that occurred in Austrian rails, copied from a publication by Dormus at Vienna in 1901. Mr. Job concludes that "traffic conditions were not the prime cause of the growth of the cracks," but that the cause of the failure is to be looked for in the condition of the steel.

"Internal Transverse Fissures in Rails.” By P. H. Dudley, Iron Age, Vol. 93, p. 492, February 14, 1914. From a report by Dr. Dudley, January 6, 1914, to the President of the New York Central Lines. Attributes the fissures to insufficient ductility in the rail head account conditions of manufacture, with conditions of service contributory.

"A Study of Interior Transverse Fissures in Rails." By P. H. Dudley, Railway Age Gazette, Vol. 56, p. 415, February 27, 1914. Editorial comment on p. 411. Illustrated article in which the fissure is attributed to various conditions of manufacture, and particularly to the bad effect of the gagging when straightening the rail.

"Internal Transverse Defects in Steel Rails." By Robert Job. Iron Age, Vol. 93, p. 660, March 12, 1914. From the article in the Railway Age Gazette, February 6, 1914.

"Transverse Fissures and Broken Rails.” Iron Age, Vol. 93, p. 1528, June 18, 1914. From Interstate Commerce Commission report on New York, New Haven & Hartford wreck nearly Westerly, R. I.

"Interstate Commerce Commission Investigation of New York, New Haven & Hartford Accident near Westerly, R. I.”. Report by Chief Inspector of Safety Appliances, dated April 24, 1914, of accident on October 25, 1913, embodying reports by J. E. Howard, Bureau of Standards, New York, New Haven & Hartford Railroad and Wirt Tassin. Mr. Howard concluded "that the proximate cause to which the transverse fissure in broken rail No. 1 are ascribed are high wheel loads, with their attending strains, evidence of other causes not having been found."

"Fatigue of Rails.” By Paul Kreuzpointner, Railway Age Gazette, Vol. 57, P. 755, October 23, 1914. A discussion of “fatigue,” or detail fracture with illustrations of the difference in the appearance of such fracture in good or sound material and in defective material.

"Interstate Commerce Commission Investigation of Delaware, Lackawanna & Western Accident near Alford, Pa." Report by Chief Inspector of Safety Appliances, dated December 31, 1914, of accident on October 31, 1914, embodying report by J. E. Howard. The conclusion is expressed "That the growth of transverse fissures is the result of repeated stresses, and their formation occurs in consequence of overloads applied to the rails in service." 1915.

"Study of a Rail With Internal Fissures." By M. H. Wickhorst. Proceedings, American Railway Engineering Association, Vol. 16 (1915). p. 195. Results of an examination of a rail that had failed in service due to transverse fissures. It showed numerous small cracks, mostly longitudinal, in the interior of the head.

"Internal Fissures in New Rails." By M. H. Wickhorst. Proceedings, American Railway Engineering Association, Vol. 16 (1915), p. 389. Illustrations are given of some small longitudinal cracks found in new rails.

"Interior Transverse Fissures.” By P. H. Dudley. Proceedings, American Railway Engineering Association, Vol. 16 (1915), p. 1120. Illustrated discussion by Dr. Dudley, presenting part of a letter to the President of the New York Central Lines. Attention is called to the harmful effect of the gag press in the cold straightening of rails.

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