90
PUBLIC RECORD OFFICE
Reference :-
TIC.O. 885
PUBLIC RECORD OFFICE, LONDON
ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC- COPYRIGHT PHOTOGRAPH-NOT TO
166
Mr. W. HARRY STANGER to Messrs. GREGORY, EYLES AND WARING. Perak Government Railways-Steel Rails and Fishplates-Requisitions
GENTLEMEN,
226 R. and 230 R.
Defective Steel Rails.
Broadway Testing Works, Westminster, S.W., July 4, 1902. Is reply to your letter of the 20th ultimo, I now beg to hand you my full report upon the defective steel rail returned from the Colony, and mentioned in the report of the Resident Engineer for Railways, dated the 22nd January, 1902, addressed to the General Manager, a copy of which you sent to me on the 21st April last.
2. On receipt of the Resident Engineer's report, at once wrote to you as per my
letter of the 23rd April.
An examination of the piece of rail returned from the Colony showed it to have defects of two kinds:-
3.
(4) Surface defects in the flanges, which must have been visible at the time
the rails were rolled.
(B) Defects on the head of the rail, which have developed and become visible by the rolling of the train loads over it, but which were not visible before the rail had been put into the road, and therefore could not be seen when the rails were rolled.
As to (A).The flange defects shown on this rail are those which occasionally occur during the rolling of flanged rails; they are so patent to the eye that the contractor's workmen throw them out as a matter of course, and do not offer them for inspection. Even if such rails were placed before the Inspector, he would certainly reject them. Any of the rails now in the Colony having flange defects similar to those on the piece of rail sent home have most certainly been shipped by the inad- vertence of the contractors.
4. At the end of every rail passed by my Inspector will be found my stamp. If that mark is not upon the rail it is one which has not been examined, and it should not have been shipped.
"
5. As to (B)-Defects on the head of the rail. As I anticipated in the final paragraph of my letter to you of the 23rd April, the results of my detailed examination into the cause of these defects prove that, in the rail in question (and doubtless in the rest of the rails which show similar defects), the metal composing these rails contains numerous flaws filled with slag, and situated below the surface of the head. The thin layer of steel above the slag flaws, while sufficient to conceal them, was not strong enough to resist the rolling action due to the loads running over it—it has spread in width and increased in length, thus-breaking up by splitting or actual tearing away from the mass of metal forming the head.
6. An analysis of the metal in the returned piece of rail has been made by Mr. Bertram Blount.
The metal submitted to analysis was taken from the centre of the head, at a part free from visible cracks and flaws. Its composition was found to be as follows:-
Carbon
Silicon
Sulphur
Phosphorus
Manganese
Iron (by difference)
Per cent.
0.235
0.084
0.081
0.063
0.848
98.689
100.000
167
of carbon, micro-structure consists essentially of polygonal grains of carbide, sur- rounded by a network of ferrite; in the present case these conditions are reversed; the bulk of the material consists of ferrite (the lighter parts of the photograph) em- bedded in carbide. This comparative poverty in carbide corresponds with the low content of carbon disclosed by the analysis.
8. A complete cross section of the rail was cut at a point where the surface of the head was smooth and free from fissures. This was polished and etched so as to display its structure, which is reproduced in the accompanying sketch (Sheet 2, Figure 1).
A longitudinal section was similarly prepared, and is shown at Figure 2, Sheet 2. An examination of these sections shows that at a short distance from the surface
of the head there is a crack extending half way across the head, and running longi- tudinally for the whole length of the specimen examined.
9. Similar sections were prepared from a part of the rail, the surface of which showed signs of injury. The structure of the rail head is shown in Sheet 3, Figures 1 and 2.
In this instance the fissures are situated closer to the surface of the rail, and are more ramified. As a result, under moderate wear the surface of the head of the rail has broken up, and flakes of metal have become separated from the mass.
10.
One of the smaller flaws such as are shown in the figures given above was examined microscopically and photographed. The photograph is appended (Sheet IV.). It represents a typical slag flaw, such as is not infrequently found in steel containing scale or oxide."
The quantity of slag in a small section of metal cut from a layer well below the surface of the head was determined, the following figure being obtained:-
9.11 per cent.
Slag and oxide
...
II. The chemical and microscopic examination of the piece of rail show that it is composed of steel of inferior quality, and that it contains flaws filled with slag situated a small distance below the surface of the head. The line of flaws is covered
2 by solid metal, which completely concealed the flaws until the rolling action of the loads had developed them.
14. You will admit that such slag flaws could not have been detected by the most careful inspection, short of the obviously impracticable course of cutting up at least one rail from every blow of the converter, and making from it full analyses and micro-photographs. Indeed, even such a drastic provveding would not entirely ensure discovery of these slag flaws. It would be necessary to make the full analytical and micro-photographic tests upon every rail, which, apart from the manifest absurdity of such a course of action, would be prohibitive, inasmuch as the cost of inspection of such a character would exceed the cost of the rails themselves.
15. The method of inspection employed in the case of these rails was in all respects similar to that which I adopt in all other cases.
Thousands of tons of steel rails have been inspected and passed at the Blaenavon Works, under my inspection, for Colonial Government Railways upon your specifica- tions and those of other Consulting Engineers to the Crown Agents for the Colonies. No such failure has before occurred in my own practice, although I have had to deal with identical failures in the practice of other Inspecting Engineers of equal experience and reputation. The cases which have come before me are but few in number, and represent an infinitesimal percentage of the rails made.
16. As desired by you, I have communicated with the Blaenavon Company, who are responsible under the guarantee, Clause 29, page 6, of your specification of 21st September, 1896, to which these rails were made.
I have, &c.,
W. HARRY STANGER.
The content of carbon is low, and that of sulphur is somewhat higher than is desirable in a good rail steel. A rail formed of such material is unduly soft, and is likely to contain numerous micro-flaws.
7. A section was cut from a part of the rail head free from fissures, and, after polishing and etching, was examined microscopically. A photograph is appended (Sheet 1). It will be seen that the structure is the reverse of that of normal rail steel of a proper hardness. In rail steel of good quality, containing 0.4 to 0.5 per cent.
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