William Metcalf

“ Some other alloy or compound may displace carbon steel, and present an entirely new set of properties, but there is nothing of the kind in sight now, and engineers need have no fear of having a new art to learn very soon. [Pg 166]
To one who has spent an ordinary business lifetime in making steel, studying it, and working with it it becomes a subject of absorbing interest, if not of love; and steel when handled reasonably is so true that “true as steel” ceases to be a metaphor, it is then a fact which fills him with the most entire confidence. ”

“ Oxygen and nitrogen are present in all steel and both are injurious, probably the most so of all impurities.
The oxides of iron are too well known to need discussion or description; they are the iron ores mixed with gangue. They are brittle, friable, hard, and weak, like sandstones. Mixed in steel they can be nothing but weakeners, elements of disintegration. Let any one take a handful of scale—or rust—oxide of iron, in his fingers and crumble it, and it will be difficult for him to imagine how such material could be anything but harmful when incorporated in steel. ”

“ The first and vital thing to be borne in mind is that all heating should be uniform throughout the mass. It has been shown that heat affects the grain, the structure, as surely as it moves the mercury-column, and such being the case it is plain that as perfect uniformity as it is possible to attain is the first essential for all heating, no matter what the ultimate object may be. ”

“ If when a bar is broken cold the fracture is uneven, with coarse grain in one part and fine grain in another, it shows that there has been uneven heating. If one side has large grain and the other side is fine, the bar has been a great deal hotter on the side having coarse grain than on the other: the heater has let the bar lie in the furnace with one side exposed to a hot flame and the other protected from the flame in some way; he has neglected to turn the bar over and heat it evenly. ”

“ Hammering and rolling heated steel affect the grain or structure profoundly; a high steel may be worked so that the grain will look mild, and a mild steel may be so worked that the grain will look hard. It is common to see a bar of steel with a fine grain at one end and a coarse grain at the other, and this state of things often frightens a consumer, who imagines that he has received a very irregular, uneven article, and he is as often astonished when it is shown to him that at the same proper heat the two ends will refine and harden equally well, and be exactly alike. ”

“ We have seen that there is a marked, definite structure of the grain of ingots due to every quantity of carbon, and also that there is a fixed limit of malleability for every quantity of carbon. It is known also that the recalescence-point shifts slightly with a change of carbon, and that it is much more marked and brighter in high-carbon steel than in low.
There are no other sure indications of the quantity of carbon present. As soon as an ingot is heated up to orange color, or the recalescent-point, it loses its distinctive structure and its fracture no longer furnishes a sure guide. ”

“ It is of great importance to the steel-user, and every engineer should try to acquire a knowledge of it in order that he may not be fooled by the carelessness or rascality of those who have preceded him. The steel-maker acquires this knowledge by daily contact with the facts; the engineer does not have it forced upon him in this way, but he should seek opportunities of observation, which will be abundant in his earlier practice when he is sent upon inspection duty. Like the structure of ingots, this heat-structure cannot be illustrated on paper, and an attempt to do so would be misleading ”

“ Few men know their own personal equations, and the best way for a steel-user to do is to tell the steel-maker what he wants to accomplish, and put upon him the responsibility of selecting the best temper.
It costs no more to make and to provide one temper than another; therefore the one inducement of the steel-maker is to give his patron that which is best adapted to his use. This plan puts all of the responsibility upon the steel-maker, just where it ought to be, because he should know more about the adaptability of his steel than any other person. ”

“ For all uses for tools steel must be hardened, or hardened and tempered. The operations of hardening and tempering, including the necessary heating, are the most important, the most delicate, and the most difficult of all of the manipulations to which steel is subjected; these operations form an art in themselves where skill, care, good judgment, and experience are required to produce reliable and satisfactory results. It is a common idea that all that is necessary is to heat a piece of steel, quench it in water, brine, or some pet nostrum, and then warm it to a certain color ”

“ While these investigations are going on, and before any definite conclusion is reached, is there any well-established safe ground for the steel-worker and the engineer to stand upon? There certainly is a good working hypothesis for all to use, and one which it is believed will always be the right one to follow no matter what the final explanation of the remarkable phenomena of hardening, tempering, and annealing may prove to be. ”

“ The reason for objecting to the quenching after forging without re-heating is that forging always sets up uneven strains in the mass; the flow is easier from the sides than from the middle of the piece, and therefore the amount of work done upon one part is greater than upon another; also it is impossible to hammer or press a piece of steel with exact uniformity throughout, so that it follows that after forging there is never exact uniformity of texture or temperature, and such uniformity is the one essential thing to insure good and even hardening. ”

“ Although we know these elements only as gases, there is no reason to suppose that their atoms may not be as potent, when added to steel, as atoms of carbon, silicon, phosphorus, or any other substance.
Such are the facts for crucible-steel as far as they are known; it is vastly more expensive than any other kind of steel, yet for the present it holds its own unique and valuable place in the arts.
For all tools requiring a fine edge for cutting purposes, such as lathe-tools, drills, taps, reamers, milling-cutters, axes, razors, pocket-knives, needles, graving-tools, etc. ”

“ Any elements in steel which reduce its strength or durability in any way may be classed as impurities.
A theoretical ideal of pure steel is a compound of iron and carbon; it is an ideal that is never reached in practice, but it is one that is aimed at by many manufacturers and consumers, because experience shows that, especially in high steels, the more nearly it is attained the more reliable and safe is the product. ”

“ When hardened and tempered, some parts will be found to be just right, and others will have a soft surface, or will not hold a good temper. The reason of this seems to be a want of uniformity in the conditions: the charcoal does not take up all of the oxygen before the steel is hot enough to be attacked, and so a decarbonized surface is formed in some parts; or it may be that some of the carbon dioxide which is formed comes in contact with the surface of the steel and takes another equivalent of carbon from it. Whatever the reaction may be, the fact is that much soft surface is formed. ”

“ For common cutlery, files, shovels, picks, battering-tools, and many such uses it contests the market with open-hearth steel; and while many engineers now specify that their structural shapes, plates, beams, angles, etc., must be of open-hearth steel, there are many eminent engineers who see no need for this discrimination, they being satisfied that if their requirements are met the process by which they are met is a matter of indifference. ”

“ This is the bane of the steel-maker’s life, and yet he must keep at this work so that he may know for himself whether anything of value has been discovered, and also that he may advise his clientage properly.
Inventions relating to the manufacture of steel have no interest for steel-users except as lively manufacturers may adopt the mistaken plan of flourishing trumpets to attract trade, not always giving a corresponding benefit to the consumer. ”

“ Half-informed, or wholly uninformed, men get a smattering of knowledge of some one or more of the well-known properties of steel, make an experiment which produces a result that is new and startling to them, and at once imagine that they have made a discovery ”

“ No steel-maker who has a proper regard for the character of his product will accept raw material upon mere analysis; analysis is of the utmost importance, for material for steel-making must be of a quality that will produce a certain quality of steel, or the result will be an inferior product. This applies to acid Bessemer and open-hearth, and to crucible-steel especially; the basic processes admit of a reduction of phosphorus not obtainable in the others.
In making fine-tool steel a bad charge in the pot inevitably means a bad piece of steel. ”

“ All pipe should be cut off; a pipe of any considerable size will show in the end of a sheared bar, and a careful observer will soon learn to detect it. If there is reason to suspect a pipe, file the place and the pipe will be revealed if it is there. Do not chip at it, for a chisel will often smooth a line which a file will bring out. In tool-steel there should not only be no pipe, there should be no star left in the bar. A “star” is a bright spot which shows the last of the pipe, not quite cut away; the steel is not solid in the star and it will not make a good cutting-edge ”

“ When an ingot is to be forged or rolled, it is well to take the highest heat possible—that immediately below the heat of granulation. Such a heat may be taken safely by keeping the steel covered with a surface flux to protect it from the flame. Ordinary red clay, dried and powdered, is an excellent flux for the purpose, and the cheapest known. Melted and powdered borax is the best of known fluxes, but it is so expensive that, as a rule, it is used only on the finest tool-steel, or on some of the alloy steels where the highest heat possible is not above a bright orange color, or hardly so high. ”

“ The effects of heat are permanent, so that it is a fact that every variation of temperature which is marked enough to be visible to the naked eye will leave a structure, due to that variation, when the steel is cold, which will be observable by the naked eye, and such structure, when not influenced by external force, such as by hammering or rolling, is as invariable and certain as is the structure of an ingot due to the quantity of carbon present. ”

“ It is the duty and the interest of a steel-maker to examine and test every apparently new suggestion, for the reason that there is still room for improvement, and he should let no opportunity for a betterment slip past him. ”

“ Red-shortness is caused chiefly by sulphur or by oxygen; many other elements may produce the same effects; it seems probable that nitrogen may be one of these, but the real action of nitrogen is as yet obscure.
A red-short steel is difficult to work; it must be worked at a high heat—from bright orange up to near the heat of granulation—or it will crack. When hardened, it is almost certain to crack. When red-short steel is worked with care into a sound condition, it may when cold be reasonably strong, but hardly any engineer of experience would be willing to trust it. ”

“ On the other hand, the beautiful work upon the most delicate and difficult shapes that is done by one skilled in the art cannot but excite the surprise and admiration of the onlooker who is familiar with the physics of steel, and who can appreciate the delicacy of handling required in the operation. ”

“ The most generally known of the alloy steels is the so-called Self-hardening steel.
Self-hardening steel is so called because when it is heated to the right temperature,—about a medium orange color,—and is then allowed to cool in the air, it becomes very hard. This steel is so easily strained that it is impossible, as a rule, to quench it in water without cracking it. It may be quenched in a blast of air without cracking, and so be made much harder than if it be allowed to cool more slowly in a quiet atmosphere. ”

“ The heat may be wild when the right carbon is reached, and then the melter must use a little ferro-silicon, or silico-spiegel, or highly silicious pig, or aluminum, and he must use good judgment so as not to have his steel overdosed with any of these. From half an ounce to an ounce of aluminum to a ton of steel is usually sufficient, and although any considerable content of aluminum is injurious to steel there is little danger of its being added, because of its cost, and because a little too much aluminum will cause the ingots to pipe from top to bottom. ”

“ When steel is heated in an open furnace, there is always a scale of oxide formed on the surface; this scale, being hard, and of the nature of sand or of sandstone, grinds away the edges of cutting-tools, so that, although the steel underneath may be soft and in good cutting condition, this gritty surface is very objectionable. This trouble is overcome by annealing in closed vessels; when charcoal is used, the difficulties just mentioned in connection with wire- and strand-annealing operate to some extent, although not so seriously, because the steel is to be machined, removing the surface. ”

“ It is within the experience of every steel-maker that men are just as variable as steel, and the successful steel-maker must familiarize himself with the personal equations of his patrons. One man on the sunny side of a street may be making an excellent kind of tool from a certain grade and temper of steel, and be perfectly happy and prosperous in its use. ”

“ Any manufacturer would rather check his melt between 10 and 15 carbon, or stop his blow so as to be sure not to overblow, if he were asked to do so, because it would save him time and expense, and it would yield sounder, better, and easier working steel.
It may not be wise yet for an engineer to fix limits as to blowing or melting, for the reason that neither he nor his assistants would know how to insure compliance, and in attempting to do it they might interfere too far with manufacturing operations and so involve themselves in responsibilities which they ought not to assume. ”

“ There is, then, a specific structure due to temperature; it is modified by carbon and by treatment under the hammer or in the rolls. If a bar of steel be heated up to the highest plastic limit, just so that it will not fall to pieces, and then cooled slowly without disturbance, and a fracture be taken, it will be found to be coarse and with an exceedingly brilliant lustre. Now let it be heated again to a bright lemon color, but still plastic, and cooled as before; it will be found to be coarse, with bright lustre, but neither so coarse nor so bright as the first piece. ”