Method for continuous heat-treatment of metals under argon atmosphere

Abstract

In heat-treating a metallic alloy containing volatile metals such as zinc, manganese, chromium, aluminium, and so on in a tunnellike continuous furnace, argon is employed as a furnace atmosphere so that a pressure selectively produced by the argon atmosphere in the furnace is utilized for preventing the volatile metals from evaporating out of the metallic alloy during its heat-treatment. The argon employed as the furnace atmosphere and having a specific gravity higher than the air prevents also the air from entering into the furnace, and works also to purge the air which has happened to come into the furnace together with the metallic alloy, whereby the furnace atmosphere is kept constantly inert.

1 . A method for heat-treating a metallic alloy, which comprises employing argon as an atmosphere of a tunnellike continuous heat-treating furnace, and heat-treating, under a pressure selectively produced by the argon atmosphere in the furnace, the metallic alloy containing one or a plurality of volatile metals such as zinc, manganese, chromium, aluminium, and so on.  
     
     
         2 . The method as claimed in  claim 1 , in which the metallic alloy is a stainless steel and a nickel based solder containing chromium, and the heat-treating is for brazing said steel with said solder.  
     
     
         3 . The method as claimed in  claim 1 , in which the metallic alloy is an article made by molding stainless steel powders, and the heat-treating is for sintering said article.  
     
     
         4 . The method as claimed in  claim 1 , in which the metallic alloy is brass containing zinc and a silver solder containing zinc, and the heat-treating is for brazing the brass with said silver solder.  
     
     
         5 . The method as claimed in  claim 1 , in which the metallic alloy is an article made by molding stainless steel powders containing manganese, and the heat-treating is for sintering said article.  
     
     
         6 . The method as claimed in  claim 1 ,  2 ,  3 ,  4 , or  5 , in which the pressure selectively produced by the argon atmosphere in the furnace is in a range from about 5.0 Pa to about 77.2 Pa.  
     
     
         7 . The method as claimed in  claim 1  or  6 , in which the pressure selectively produced by the argon atmosphere in the furnace is changed by the height of an inlet and outlet which are for charging and discharging the metallic alloy into and from the tunnellike continuous heat-treating furnace and which work as outstanding heads.  
     
     
         8 . The method as claimed in  claim 1  or  6 , in which the pressure selectively produced by the argon atmosphere in the furnace is raised by slantingly elevating an inlet and outlet which are for charging and discharging the metallic alloy into and from the tunnellike continuous heat-treating furnace.