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Steel MakingCorrection For Cold-junction ErrorsThe voltage generated by a thermo-couple of an electric pyrom... Temperatures To Use As soon as the temperature of the steel reaches 100 deg.C. (... Quality And Structure The quality of high-speed steel is dependent to a very great ... Carburizing Material The simplest carburizing substance is charcoal. It is also th... The Thermo-couple With the application of the thermo-couple, the measurement of... The Forging Of Steel So much depends upon the forging of steel that this operation... Instructions For Working High-speed Steel Owing to the wide variations in the composition of high-speed... Annealing Work With the exception of several of the higher types of alloy s... Critical Points One of the most important means of investigating the properti... Carbon-steel Forgings Low-stressed, carbon-steel forgings include such parts as car... High-carbon Machinery Steel The carbon content of this steel is above 30 points and is ha... Pyrometers Armor plate makers sometimes use the copper ball or Siemens' ... For Milling Cutters And Formed Tools FORGING.--Forge as before.--ANNEALING.--Place the steel in a ... Preparing Parts For Local Case-hardening At the works of the Dayton Engineering Laboratories Company, ... Introduction Of Carbon The matter to which these notes are primarily directed is the... Oil-hardening Steel Heat slowly and uniformly to 1,450 deg.F. and forge thorough... Separating The Work From The Compound During the pulling of the heat, the pots are dumped upon a ca... Hardening High-speed Steel In forging use coke for fuel in the forge. Heat steel slowly ... Carbon Steels For Different Tools All users of tool steels should carefully study the different... Non-shrinking Oil-hardening Steels Certain steels have a very low rate of expansion and contract... |
Liberty Motor Connecting RodsCategory: ALLOYS AND THEIR EFFECT UPON STEEL The requirements for materials for the Liberty motor connecting rods are so severe that the methods of securing the desired qualities will be of value in other lines. The original specifications called for chrome-nickel but the losses due to the difficulty of handling caused the Lincoln Motor Company to suggest the substitution of chrome-vanadium steel, and this was accepted by the Signal Corps. The rods were accordingly made from chromium-vanadium steel, containing carbon, 0.30 to 0.40 per cent; manganese, 0.50 to 0.80 per cent; phosphorus, not over 0.04 per cent; sulphur, not over 0.04 per cent; chromium, 0.80 to 1.10 per cent; vanadium, not less than 0.15 per cent. This steel is ordinarily known in the trade as 0.35 carbon steel, S. A. E., specification 6,135, which provides a first-rate quality steel for structural parts that are to be heat-treated. The fatigue resisting or endurance qualities of this material are excellent. It has a tensile strength of 150,000 lb. minimum per square inch; elastic limit, 115,000 lb. minimum per square inch; elongation, 5 per cent minimum in 2 in.; and minimum reduction in area, 25 per cent. The original production system as outlined for the manufacturers had called for a heat treatment in the rough-forged state for the connecting rods, and then semi-machining the rod forgings before giving them the final treatment. The Lincoln Motor Company insisted from the first that the proper method would be a complete heat treatment of the forging in the rough state, and machining the rod after the heat treatment. After a number of trial lots, the Signal Corps acceded to the request and production was immediately increased and quality benefited by the change. This method was later included in a revised specification issued to all producers. The original system was one that required a great deal of labor per unit output. The Lincoln organization developed a method of handling connecting rods whereby five workmen accomplished the same result that would have required about 30 or 32 by the original method. Even after revising the specification so as to allow complete heat treatments in the rough-forged state, the ordinary methods employed in heat-treating would have required 12 to 15 men. With the fixtures employed, five men could handle 1,300 connecting rods, half of which are plain and half, forked, in a working period of little over 7 hr. The increase in production was gained by devising fixtures which enabled fewer men to handle a greater quantity of parts with less effort and in less time. In heat-treating the forgings were laid on a rack or loop A, Fig. 14, made of 1-1/4-in. double extra-heavy pipe, bent up with parallel sides about 9 in. apart, one end being bent straight across and the other end being bent upward so as to afford an easy grasp for the hook. Fifteen rods were laid on each loop, there being four loops of rods charged into a furnace with a hearth area of 36 by 66 in. The rods were charged at a temperature of approximately 900 deg.F. They were heated for refining over a period of 3 hr. to 1,625 deg.F., soaked 15 min, at this degree of heat and quenched in soluble quenching oil. In pulling the heat to quench the rods, the furnace door was raised and the operator pulls one of the loops A, Fig. 15 forward to the shelf of the furnace, supporting the straight end of the loop by means of the porter bar B. They swung the loop of rods around from the furnace shelf and set the straight end of the loop on the edge of the quenching tank, then raise the curved end C, by means of their hook D so that all the rods on the loop slide into the oil bath. Before the rods cooled entirely, the baskets in the quenching tank were raised and the oil allowed to partly drain off the forgings, and they were stacked on curved-end loops or racks and charged into the furnace for the second or hardening heat. The temperature of the furnace was raised in 1-1/2 hr. to 1,550 deg.F., the rods soaked for 15 min. at this degree of heat and quenched in the same manner as above. They were again drained while yet warm, placed on loops and charged into the furnace for the third or tempering heat. The temperature of the furnace was brought to 1,100 deg.F. in 1 hr., and the rods soaked at this degree of heat for 1 hr. They were then removed from the furnace the same as for quenching, but were dumped onto steel platforms instead of into the quenching oil, and allowed to cool on these steel platforms down to the room temperature. Next: Pickling The Forgings Previous: Corrosion
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