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Steel MakingS A E Heat TreatmentsThe Society of Automotive Engineers have adopted certain heat... Tensile Properties Strength of a metal is usually expressed in the number of pou... Hardening The forgings can be hardened by cooling in still air or quen... Lathe And Planer Tools TO FORGE.--Gently warm the steel to remove any chill is parti... Vanadium Vanadium has a very marked effect upon alloy steels rich in c... The Theory Of Tempering Steel that has been hardened is generally harder and more br... The Care Of Carburizing Compounds Of all the opportunities for practicing economy in the heat-t... Chrome-nickel Steel Forging heat of chrome-nickel steel depends very largely on ... William Kelly's Air-boiling Process An account of Bessemer's address to the British Association w... Lathe And Planer Tools FORGING.--Gently warm the steel to remove any chill, is parti... Using Illuminating Gas The choice of a carburizing furnace depends greatly on the fa... Robert Mushet Robert (Forester) Mushet (1811-1891), born in the Forest of D... Refining The Grain This is remedied by reheating the piece to a temperature slig... Classifications Of Steel Among makers and sellers, carbon tool-steels are classed by g... Fatigue Tests It has been known for fifty years that a beam or rod would fa... Nickel-chromium A combination of the characteristics of nickel and the charac... The Effect Of Tempering On Water-quenched Gages The following information has been supplied by Automatic and ... Placing The Thermo-couples The following illustrations from the Taylor Instrument Compan... The Thermo-couple With the application of the thermo-couple, the measurement of... The Leeds And Northrup Potentiometer System The potentiometer pyrometer system is both flexible and subst... |
Knowing What Takes PlaceCategory: HARDENING CARBON STEEL FOR TOOLS How are we to know if we have given a piece of steel the very best possible treatment? The best method is by microscopic examination of polished and etched sections, but this requires a certain expense for laboratory equipment and upkeep, which may prevent an ordinary commercial plant from attempting such a refinement. It is highly recommended that any firm that has any large amount of heat treatment to do, install such an equipment, which can be purchased for from $250 to $500. Its intelligent use will save its cost in a very short time. The other method is by examination of fractures of small test bars. Steel heated to its correct temperatures will show the finest possible grain, whereas underheated steel has not had its grain structure refined sufficiently, and so will not be at its best. On the other hand, overheated steel will have a coarser structure, depending on the extent of overheating. To determine the proper quenching temperature of any particular grade of steel it is only necessary to heat pieces to various temperatures not more than 20 deg.C. (36 deg.F.) apart, quench in water, break them, and examine the fractures. The temperature producing the finest grain should be used for annealing and hardening. Similarly, to determine tempering temperatures, several pieces should be hardened, then tempered to various degrees, and cooled in air. Samples, say six, reheated to temperatures varying by 100 deg. from 300 to 800 deg.C. will show a considerable range of properties, and the drawing temperature of the piece giving the desired results can be used. For drawing tempers up to 500 deg.F. oil baths of fresh cotton seed oil can be safely and satisfactorily used. For higher temperature a bath of some kind of fused salt is recommended. Next: Hints For Tool Steel Users Previous: Temperatures To Use
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