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Steel MakingS A E Heat TreatmentsThe Society of Automotive Engineers have adopted certain heat... Carbon Steels For Different Tools All users of tool steels should carefully study the different... Effects Of Proper Annealing Proper annealing of low-carbon steels causes a complete solu... Sulphur Sulphur is another impurity and high sulphur is even a greate... Refining The Grain This is remedied by reheating the piece to a temperature slig... Liberty Motor Connecting Rods The requirements for materials for the Liberty motor connecti... Complete Calibration Of Pyrometers For the complete calibration of a thermo-couple of unknown e... Crankshaft The crankshaft was the most highly stressed part of the entir... Placing Of Pyrometers When installing a pyrometer, care should be taken that it re... Introduction Of Carbon The matter to which these notes are primarily directed is the... Compensating Leads By the use of compensating leads, formed of the same materia... Phosphorus Phosphorus is one of the impurities in steel, and it has been... The Theory Of Tempering Steel that has been hardened is generally harder and more br... Carbon-steel Forgings Low-stressed, carbon-steel forgings include such parts as car... Plant For Forging Rifle Barrels The forging of rifle barrels in large quantities and heat-tre... A Chromium-cobalt Steel The Latrobe Steel Company make a high-speed steel without tun... Blending The Compound Essentially, this consists of the sturdy, power-driven separa... Silicon Silicon prevents, to a large extent, defects such as gas bubb... Drop Forging Dies The kind of steel used in the die of course influences the he... Carburizing Material The simplest carburizing substance is charcoal. It is also th... |
Chrome-nickel SteelCategory: THE FORGING OF STEEL Forging heat of chrome-nickel steel depends very largely on the percentage of each element contained in the steel. Steel containing from 1/2 to 1 per cent chromium and from 1-1/2 to 3-1/2 per cent nickel, with a carbon content equal to the chromium, should be heated very slowly and uniformly to approximately 1,600 deg. F., or salmon color. After forging, reheat the steel to about 1,450 deg. and cool slowly so as to remove forging strains. Do not attempt to harden the steel before such annealing. A great deal of steel is constantly being spoiled by carelessness in the forging operation. The billets may be perfectly sound, but even if the steel is heated to a good forging heat, and is hammered too lightly, a poor forging results. A proper blow will cause the edges and ends to bulge slightly outwards--the inner-most parts of the steel seem to flow faster than the surface. Light blows will work the surface out faster; the edges and ends will curve inwards. This condition in extreme cases leaves a seam in the axis of the forging. Steel which is heated quickly and forging begun before uniform heat has penetrated to its center will open up seams because the cooler central portion is not able to flow with the hot metal surrounding it. Uniform heating is absolutely necessary for the best results. Figure 16 shows a sound forging. The bars in Fig. 17 were burst by improper forging, while the die, Fig. 18, burst from a piped center. Figure 19 shows a piece forged with a hammer too light for the size of the work. This gives an appearance similar to case-hardening, the refining effect of the blows reaching but a short distance from the surface. While it is impossible to accurately rate the capacity of steam hammers with respect to the size of work they should handle, on account of the greatly varying conditions, a few notes from the experience of the Bement works of the Niles-Bement-Pond Company will be of service. For making an occasional forging of a given size, a smaller hammer may be used than if we are manufacturing this same piece in large quantities. If we have a 6-in. piece to forge, such as a pinion or a short shaft, a hammer of about 1,100-lb. capacity would answer very nicely. But should the general work be as large as this, it would be very much better to use a 1,500-lb. hammer. If, on the other hand, we wish to forge 6-in. axles economically, it would be necessary to use a 7,000- or 8,000-lb. hammer. The following table will be found convenient for reference for the proper size of hammer to be used on different classes of general blacksmith work, although it will be understood that it is necessary to modify these to suit conditions, as has already been indicated. Diameter of stock Size of hammer 3-1/2 in. 250 to 350 lb. 4 in. 350 to 600 lb. 4-1/2 in. 600 to 800 lb. 5 in. 800 to 1,000 lb. 6 in. 1,100 to 1,500 lb. Steam hammers are always rated by the weight of the ram, and the attached parts, which include the piston and rod, nothing being added on account of the steam pressure behind the piston. This makes it a little difficult to compare them with plain drop or tilting hammers, which are also rated in the same way. Steam hammers are usually operated at pressures varying from 75 to 100 lb. of steam per square inch, and may also be operated by compressed air at about the same pressures. It is cheaper, however, in the case of compressed air to use pressures from 60 to 80 lb. instead of going higher. Forgings must, however, be made from sound billets if satisfactory results are to be secured. Figure 20 shows three cross-sections of which A is sound, B is badly piped and C is worthless. Next: Plant For Forging Rifle Barrels Previous: Oil-hardening Steel
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