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Steel MakingDetrimental ElementsSulphur and phosphorus are two elements known to be detrimen... Judging The Heat Of Steel While the use of a pyrometer is of course the only way to hav... Surface Carburizing Carburizing, commonly called case-hardening, is the art of pr... Application Of Liberty Engine Materials To The Automotive Industry The success of the Liberty engine program was an engineer... Instructions For Working High-speed Steel Owing to the wide variations in the composition of high-speed... Manganese Manganese adds considerably to the tensile strength of steel,... Impact Tests Impact tests are of considerable importance as an indication ... Steel Worked In Austenitic State As a general rule steel should be worked when it is in the a... Preventing Carburizing By Copper-plating Copper-plating has been found effective and must have a thick... Piston Pin The piston pin on an aviation engine must possess maximum res... Tempering Colors On Carbon Steels Opinions differ as to the temperature which is indicated by t... Annealing Of High-speed Steel For annealing high-speed steel, some makers recommend using g... Machineability Reheating for machine ability was done at 100 deg. less than ... Cyanide Bath For Tool Steels All high-carbon tool steels are heated in a cyanide bath. Wi... Process Of Carburizing Carburizing imparts a shell of high-carbon content to a low-... Pyrometry And Pyrometers A knowledge of the fundamental principles of pyrometry, or th... Quenching The Work In some operations case-hardened work is quenched from the bo... Heating Although it is possible to work steels cold, to an extent de... Heat Treatment Of Steel Heat treatment consists in heating and cooling metal at defin... Hardening High-speed Steel In forging use coke for fuel in the forge. Heat steel slowly ... |
QuenchingCategory: CASE-HARDENING OR SURFACE-CARBURIZING It is considered good practice to quench alloy steels from the pot, especially if the case is of any appreciable depth. The texture of carbon steel will be weakened by the prolonged high heat of carburizing, so that if we need a tough core, we must reheat it above its critical range, which is about 1,600 deg.F. for soft steel, but lower for manganese and nickel steels. Quenching is done in either water, oil, or air, depending upon the results desired. The steel is then very carefully reheated to refine the case, the temperature varying from 1,350 to 1,450 deg.F., depending on whether the material is an alloy or a simple steel, and quenched in either water or oil. There are many possibilities yet to be developed with the carburizing of alloy steels, which can produce a very tough, tenacious austenitic case which becomes hard on cooling in air, and still retains a soft, pearlitic core. An austenitic case is not necessarily file hard, but has a very great resistance to abrasive wear. The more carbon a steel has to begin with the more slowly will it absorb carbon and the lower the temperature required. Low-carbon steel of from 15 to 20 points is generally used and the carbon brought up to 80 or 85 points. Tool steels may be carbonized as high as 250 points. In addition to the carburizing materials given, a mixture of 40 per cent of barium carbonate and 60 per cent charcoal gives much faster penetration than charcoal, bone or leather. The penetration of this mixture on ordinary low-carbon steel is shown in Fig. 32, over a range of from 2 to 12 hr. Next: Effect Of Different Carburizing Material Previous: Carburizing Material
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