Steel

(1) An excellent composition for welding cast - steel is prepared by boiling together 16 parts borax and 1 of sal - ammoniac over a slow fire for 1 hour. When cold, grind it to powder. The steel must then be made as hot as it will conveniently bear, and the composition used the same as sand.

(2) There is one point in welding steel which cannot be too strongly insisted upon, and that is that the pieces, after having been brought to welding - point, should not be struck heavily with the hammer, but only tapped lightly at first until they have begun to weld; after that, the sledge or steam hammer may be used with perfect freedom. Another important thing in welding steel is the heat. While it is impossible to give any specific rules on this point, the general rule, which will be found to hold good in all cases, is not to heat the steel any higher than is absolutely necessary to effect a weld - the higher the steel is in carbon the lower the heat at which it ought to be worked, hence necessitating heavier hammers - and next, not to finish the operation at too low a temperature. It will be best to work the steel as rapidly as possible, reheat as often as required to prevent working or finishing cold, and anneal immediately after welding the whole piece - not only the immediate vicinity - containing a weld. The annealing heat should always be higher than that at which the piece was finished. Another source of danger to the homogeneity of the finished product is to be found in cold - straightening.

The presses in many mills are so constructed as to exert absolute shearing stresses, and are apt to do more harm than any subsequent service can do. Cold - straightening ought to be done at black heat, and the local effects of the press be modified by distribution over a large area. This can be accomplished by the use of broad oak wedges or the insertion of pieces of plank. Generally, plates, angles, beams, etc, have of necessity to undergo more or less hammering in the course of construction, and as this produces effects comparable to punching and shearing, though in a much less degree, it becomes necessary, in steel construction, to modify these effects in the same way by protecting the metal surface with wood and substituting heavy wooden mallets for sledges. In time, the working of steel in every stage requires care-and, above all, intelligence - and the men engaged in it must be impressed with the necessity for careful manipulation and rational treatment. Undoubtedly the steel must possess the proper qualities for structural purposes in the first place, but then it must also be properly treated subsequently if it is to bring those qualities into the finished structure. (A. Hill.)

(3) Shear and double - shear steel are easily welded, and the latter will answer almost all the purposes of cast - steel. Cast - steel, however, is more difficult to weld, but it can be done by practice. Care must be taken not to heat too hot, or it will fall to pieces under the hammer. Use powdered borax as a flux.

(4) A mass of ingredients is sold for the purpose of welding cast - steel, but the simplest and best method is, according to the Revue Industrielle, the one employed by Fiala, of Prague, Bohemia. He uses pulverized white marble for the purpose. The 2 pieces to be welded together are heated, and, after rolling in marble dust, are promptly joined together, and subjected to a good hammering.

(5) Cast - steel can be, and is, successfully welded; but there is greater difficulty in the accomplishment of the process than with other kinds of steel, and it requires a practical hand to make a good job. The precautions necessary to ensure success are as follows:- Keep it from the air while being heated; heat as quickly as possible; don't make it too hot, or it will burn, and break in pieces when hammered - for cast - steel requires a low welding - heat; strike lightly at first, and increase to heavy blows; don't use coals, for they contain sulphur, and will give the surface of the steel a coating of sulphide of iron; but use coke, or what smiths term " breeze," that is, coal well burnt and the cinders washed. Use the following flux:- Borax 1/4 lb., washing potash 1/4 lb., and a small quantity of white glass, powdered; melt together, and when cold, pound it. This flux will dissolve the oxide that forms. Apply some before putting in the fire, to protect surface of work from oxide, and apply more at your own discretion.

If wanted to weld cast - steel to iron, the iron will require a greater heat than the steel.

(6) The sand usually employed must be discarded, and borax employed in its stead. Some of the cast - steels require a still more fusible flux than even borax, and sal - ammoniac is mingled with it; 1 of sal - ammoniac to 15 or 20 of borax is sufficient. The best mode of using borax is to put it in an iron kettle or ladle over the fire, and heat it until it discontinues to boil up, then cold, reduce it to a powder. When the steel is somewhat heated, the powdered borax is applied, and when again inserted in the fire, the heat is raised as high as the steel will bear without injury. When at the point of fusion, on to the anvil with it quickly; hit it lightly, very lightly, at first, till it begins to adhere, and increase the force of the blows by degrees. If the joint is not satisfactory, try a second heat with another application of the borax.

(7) Put 1/4 lb. saltpetre, and 1/4 lb. oil of vitriol, in 2 gal. water, heat ends of steel red - hot, and cool them in the mixture before welding. Make a longer scarf than for iron, using nothing but sand while heating; but be sure to get sand with a glassy grain, and free from sulphur. Heat high above the iron, roll your heats well in the sand, keeping plenty on the off side, for it melts and runs below, and forms a capital flux. Be careful not to heat too high. Don't brush your heats, or you will take away the flux; if there be any dirt on them just tip it off, and you will have a good solid weld. If you don't get it solid with first heat, you can take another heat over all, using sand the same as at first.

(8) The cheapest flux is a piece of soft clay. First get your heats to a cherry - red in a clear fire; then just dip in the clay. You will find it form a thin coat on the scarf; then put your heats in the fire, and when you see the clay run off the point of the scarf, it is right to weld; but be careful not to get your heats too hot behind the scarf. In shutting your heats, tap them lightly till you feel them begin to stick, then you can have your hammers down on it.

(9) There are so many grades or tempers of cast - steel now in use (from steel rails to surgical instruments) that there is a great difficulty in understanding what is meant by cast - steel. The old system of steel - making was the converted or cemented process; the converted bars were welded once or twice, then called single or double shear-steel, according to treatment received. In the Huntsman or crucible process, the converted bars were broken up into small pieces and charged into crucibles along with oxide of manganese, etc, and when melted, cast into ingots, hence the term cast, to distinguish from shear - steel. We have 3 methods by which cast - steel is produced, i.e. Bessemer, Siemens, and Huntsman (crucible) processes, and the various qualities and tempers manufactured by these are legion. Some of these steels will weld without any difficulty, and some with only the greatest difficulty; some kinds will harden very hard when plunged into water at a red heat, and others, when subject to the same treatment, will bend over and over without showing any signs of a fracture, the sudden cooling having made no perceptible difference; yet both are cast - steel, and probably may have been made from the same process.

Cast - steel rails arc sold at about 9/. per ton, cast - steel for tools at 60/. to 140/. per ton.

(10) Two points must be taken into consideration chiefly in effecting the welding of steel: it is necessary to render the film of oxidized iron on the surfaces to be united by welding as fluid as possible, and some means must be found to restore to the steel the carbon eliminated during the process of heating to the welding temperature. According to the Revue industrielle, Rust considers boric acid the most effectual in performing the former, and ferrocyanide of potassium in doing the latter. Rust considers the functions of the ferrocyanide to be also to restore to the steel nitrogen, upon which he looks as an important constituent of the" metal. In 1850, a workman of Mul - house, Alsace, sold the following recipe for a welding compound: 65 parts borax, 20 of sal - ammoniac, 10 of potassium ferrocyanide, and 5 of colophony. Rust changed it as follows: - 61 of borax, 17 1/4 of sal - ammoniac, 16f of ferrocyanide, and 5 of colophony. He states that, with the aid of this compound, welding may be accomplished at a yellow - red, or at a temperature between the yellow - red and white, and that no treatment is necessary after welding. The borax and sal - ammoniac are powdered, mixed, and are slowly heated until they melt.

Heating is continued until the strong odour of ammonia ceases almost entirely, a small quantity of water being added to make up for that lost by evaporation. The powdered ferrocyanide is then added, together with the colophony, and the heating is continued until a slight smell of cyanogen is noticed. The mixture is allowed to cool by spreading it out in a thin layer. During the process given, boric acid and chloride of sodium are formed, ammonia being expelled. The same product may therefore be obtained by mixing 41 '5 parts boric acid, 35 of dry sodium chloride (salt), 15.5 to 26.7 of potassium ferrocyanide, 7.6 of colophony, and 3 to 5 of dry soda carbonate. The only trouble with this mixture, which gives the same results, is that it decomposes easily, unless it is kept in a dry place.