Parameters of endogases in controlled atmospheres for heating chromium steels to quenching temperatures
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The use of endothermic protective atmospheres with a dew point of −6 to −8°C for heating ShKh15 steel parts to quenching temperatures eliminates scale formation and induces very small changes in the amount of carbon in the surface layer.
To lighten the load on the endothermic generator we added natural gas to the furnace. However, the amount of natural gas added should not exceed 1% by volume, since when more than 1% methane is added to the endogas the value of the carbon potential ceases to be proportional to the dew point temperature of the furnace atmosphere.
The use of a protective atmosphere eliminates the necessity of making the articles oversize in order to grind off the decarburized layer. In this case the oversize depends on the deformation due to quenching and the finishing operations.
When furnaces are modernized in view of using protective atmospheres which evolve soot, the open heating elements operating on 380 V should be replaced with heating elements enclosed in radiant tubes or with open heating operating on low voltage.
KeywordsFurnace Point Temperature Scale Formation Control Atmosphere Carbon Potential
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- 1.A. D. Hotchkiss, and C. M. Webber, Protective Atmospheres [Russian translation], Mashgiz, (1959).Google Scholar