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TABLE XVII. Alternations endured under standard conditions. Direction of plane of maximum stress. At right angles Parallel with Series No. to MnS rods. MnS rods. 1 283 193- 2 293 118+ 3 303 117% *Mean -of. 12 tests in each direction. +Mean of 6 tests in each direction. tMean of 6 tests in each direction. It may be remarked that all the epove shafts fracturéd in use... The direction of the sulphide rods in: re- lation to the plane of maximum stress on the author's machine will be clear on. reference to thé diagram in Fig. 16. The 24 fractures of the bars tested with the maximum stress plane parallel with the su'phide lines showed "fiber," which was quite ab- sent from the 24 bars tested plane of maximum stress at angle to the MnS rods: ON POSSIBLE REMEDIAL MEASURES. A little time ago the author sub- mitted to Sir William White a few of the somewhat disconcerting facts described in this paper, and, while Sir William White fully agreed that it in the right was desirable to publish them, os pointed out that a more valuable fea- ture in such a paper would be: to propose therein the steps. which should be taken to prevent, as far as possible, the manufacture of steel forg- ings of doubtful quality, for marine and other engineering purposes. It is easy to formulate airy proposals, provided that the proposer belongs to the class by which an eminent but gloomy author has declared our island is chiefly populated. Such might take up the case with alacrity, while an- Other abstract class of the community, although popularly supposed to be provided with wings, would strongly hesitate to step in; but, as the au- thor is well aware that steel makers will welcome any well-considered pro- posals to improve the quality, espe- cially of large masses of steel, and engineers earnestly wish to secure ad- equate elasticity in their materials of construction, he, with much diffidence, will venture on a few suggestive re- marks in the direction indicated by Sir William White. Remarks on Ingots.--The necessity of rejecting a sufficient weight of the upper part of a large ingot to insure the absence in the steel used for forg- ing of liquated regions, pipes, and _ Pockets, is too well known to need any remark, but even in the lower Portions of such an ingot, presumably of good steel, it is practically impos- sible with a mean sulphur and phos- Phorus of 0.04 to 0.05 per cent each to avoid some segregation areas, if shown 'ingot. 'TAE. Marine REVIEW the ingot be allowed to cool at at- mospheric pressure, hence the pro- duction of some ghost -lines is inevita- ble; but if, as is sometimes the case, inferior steels containing up to 0.10 per cent each of sulphur and _ plos- phorus are accepted, the mischief is greatly aggravated. In the author's opinion, in all heavily stressed engine parts the maximum phosphorus and sulphur should never exceed 0.05 per cent each. Even with low sulphur and phosphorus it is desirable to re- duce segregation to a minimum, and, so far as the author's knowledge goes, the only reliable and practical way to bring about this consummation is to cool the ingot under fluid compres- sion, as long carried out by the Whit- worth process or by recent develop- ments of the original idea devised by Harmet and by Messrs. Robinson and Rodger, of Sheffield. But nearly one- third from the top of the Whitworth ingot there is a large bright cavity or pocket full of mixed gases consist- ing chiefly of hydrogen and nitrogen, and in the vicinity of this pocket there is serious segregation, which is, of course, got rid of by cutting away the upper part of the ingot well below the pocket. The Whitworth ingot is exceedingly clean, this fact conducing to sound forging, and it is relatively free from segregation compared with a similar ingot allowed to cool spon- taneously at atmospheric pressure. The maximum size of ingot to which the application of Whitworth fluid compression is effective is an open question. The Harmet process of bottom pressure seems very successful in pre- venting segregation. 'The waste is much less than with the Whitworth process, although the skin is hardly so clean as that of the Whitworth Unfortunately the view ex- pressed to the author by an experi- enced and competent expert is that a relatively small, say 20-ton ingot, must be regarded as the limit to which bot- tom fluid compression by the Harmet 'method can be effectively applied. The Heat Treatment of Forgings.--In the author's view anything like a pro- 'tracted cooling, especially at a low red heat, is dangerous, and likely to unduly lower the elastic limit of the steel under treatment. Three other methods* suggest them- selves: : : 1. When the forging operation 1s over, let the forging cool in air as. far *The author .has purposely refrained from discussing the possibility of always securing chemically an adequate elasticity by the intro- duction of special elements. This aspect of the subject. is a very large one, but is well worthy of serious consideration and ipvestiBa tion. 45 as possible out of drafts, and apply no further heat treatment. 2. Re-heat the forging to about 900° C.. quench in oil, and: finally "let down" by re-heating to a temperature between 300° and 400° C. 3. Re-crystallize the steel and re- move, stresses from the forging by heating to about 900° C., or at any rate above Osmond's top critical change point Acs; and then cool as quickly as the circumstances of the case' will" permit; in "air; in? other words, normalize the material. In the opinion of the author method 3 is likely to give the best average results. -- Mechanical Testing of Forgings--The author regards kinetic tests as useful for experimental investigations, or oc- casionally desirable as an auxiliary method in cases of doubtful material. The static test must always be the main method of testing as between engineer and metallurgist, but the au- thor most strongly advocates the abandonment of maximum stress as a base for the calculations of factors of safety. It has become urgent for the marine engineer to secure invari- ably an approximate measurement of the real elastic limit of the steel he uses. In connection with certain parts of machinery it is much easier to ten- der this advice than to show how it is to be followed under manufacturing conditions. It is, however, quite clear that all test pieces should be taken from the heat-treated forging before machining the latter, and that the por- tion taken for testing should be really representative of the mass of metal from which it is detached. As a base for calculations the yield point or apparent elastic limit offers the most promising features, since it is gener- -- aly connected with a decisive drop in the beam of the testing machine, and is consequently almost as easily, though not quite so accurately, deter- minable as the maximum stress. The latter, of course, should always be noted so as to obtain a reasonable ratio between the yield point and the maximum stress, say, from 45 to 55 per cent. It would, however, be quite futile to attempt to lay down dogmatic relations for this matter, be- cause, steadily bearing in mind the obviously desirable end that the en- gineer should always have a reason- ably accurate idea of the elasticity and, in special cases, of the resist- ance to alternating stress of the ma- terials he fashions into such awe-in- spiring forms, the points at issue must be settled on their merits by mutual and amicable arrangements between engineer and steel maker.