KR830004433A - Protective atmosphere treatment method for annealing and spheroidizing metal iron - Google Patents

Abstract

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Description

Protective atmosphere treatment method for annealing and spheroidizing metal iron

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Claims (12)

In order to heat the ferrous metal product to be treated, it is put in a furnace maintained at a temperature above the transformation temperature, and a composition composed essentially of 0.1-1.0 mole percent methanol and residual nitrogen is added to the furnace. Act to create a protective furnace atmosphere that inhibits recarburization; The product is held at the furnace atmosphere temperature until the product undergoes crystal transformation with austenite; A method of annealing ferrous metal products, comprising the step of cooling the product at a rate to provide an ambient temperature microstructure by subsequent assembly operations applied to the product. The method according to claim 1, wherein the gas complex entering the furnace consists of 0.5-0.6 mole percent methanol and residual nitrogen. The method according to claim 1, wherein the furnace has a plurality of zones maintained at temperatures above and below the transformation temperature of the product to be treated. The process according to claim 1, wherein the furnace has a plurality of heating zones, cooling zones and passage outlets for the cooling zone and passage passages which are generally cleaned with pure nitrogen. The process according to claim 1, wherein the mixture introduced into the furnace consists of 0.5-3 mole percent methanol, residual nitrogen. A method according to claim 1 wherein the mixture entering the furnace is adjusted to recover carbon on the surface of the ferrous metal product annealed. A method for spheroidizing ferrous metal products by combining heating and cooling in order to obtain a microstructure in round or spherical carbides, the composition comprising 0.5-10 mole percent methanol and residual nitrogen. An improved composition consisting of heating and cooling the ferrous metal product under an atmosphere prepared by forming a mixture and introducing the composite into the furnace to prevent the removal of surface carbon from the ferrous product while the product is heated and cooled. Way. The method according to claim 7, wherein the product is heated to a maximum temperature below the transformation temperature, held in the atmosphere for a time sufficient to form spherical carbides, and then slowly cooled to room temperature. The method according to claim 7, wherein the product is heated to a temperature above the transformation temperature for cooling with the austenite, the microstructure of the product is cooled, maintained at a temperature below the transformation temperature and then slowly cooled to ambient temperature in the air. The method according to claim 7, wherein the product is alternately heated and cooled in an atmosphere to a temperature above and below the transformation temperature of the product. The method according to claim 7, wherein the composition is 0.5-6 mole percent methanol, residual nitrogen. The method according to claim 7, wherein the composite can be adjusted to recover carbon on the surface of the ferrous metal product. ※ Note: The disclosure is based on the initial application.