Method for solution heat treatment of 6201 aluminum alloy

Claim 1

A method of continuously casting and rolling a heat treatable hot formed aluminum base alloy product comprising: casting a molten aluminum base alloy metal in a continuous casting mold; cooling said molten aluminum base alloy metal during casting to form a cast bar at a temperature above that temperature at which the alloying metals present in said aluminum base alloy metal would precipitate to the grain boundaries of said aluminum base alloy metal and at a rate at which solidification shrinkage will not occur; continuously removing said cast bar from said continuous casting mold and passing said cast bar to a hot rolling mill wherein said cast bar is hot formed into a wrought rod; initiating the step of hot forming the cast bar while the cast bar is at a temperature within the hot forming temperature range of the metal and which temperature is a solutionizing temperature of the metal, continuing the hot forming step while maintaining the temperature of the cast bar within the hot forming temperature range; immediately after the hot forming step and before any substantial cooling of the wrought rod, continuously passing the wrought rod to an in-line heater for approximately five seconds or less wherein the temperature of said wrought rod is raised to a temperature which is a solutionizing temperature of the metal and maintaining the temperature of the wrought rod for a time sufficient to solution heat treat said wrought rod and reducing the temperature of the wrought rod after the solution heat treating step at a rate so as to reduce the temperature of the wrought rod from the solutionizing temperature to a temperature at which no substantial immediate precipitation of alloying metal occurs.

Claim 2

A method of continuously casting and rolling a heat treatable hot formed aluminum base alloy product comprising: casting a molten aluminum base alloy metal in a continuous casting mold; cooling said molten aluminum base alloy metal during casting to form a cast bar at a temperature above that temperature at which the alloying metals present in said aluminum base alloy metal would precipitate to the grain boundaries of said aluminum base alloy metal and at a rate at which solidification shrinkage will not occur; continuously removing said cast bar from said continuous casting mold and passing said cast bar to a hot rolling mill wherein said cast bar is hot formed into a wrought rod; initiating the step of hot forming the cast bar while the cast bar is at a temperature within the hot forming temperature range of the metal and which temperature is a solutionizing temperature of the metal, continuing the hot forming step while maintaining the temperature of the cast bar within the hot forming temperature range; immediately after the hot forming step and before any substantial cooling of the wrought rod, continuously passing the wrought rod to an in-line heater for approximately five seconds or less wherein the temperature of said wrought rod is raised to a temperature which is a solutionizing temperature of the metal and maintaining the temperature of the wrought rod for a time sufficient to solution heat treat said wrought rod and reducing the temperature of the wrought rod after the solution heat treating step at a rate so as to reduce the temperature of the wrought rod from the solutionizing temperature to a temperature at which no substantial immediate precipitation of alloying metal occurs.

Claim 3

A method of continuously casting an aluminum base alloy rod containing from about 0.5 to about 0.9 weight percent silicon, about 0.6 to about 0.9 weight percent magnesium and the remainder essentially aluminum comprising the steps of: (a) pouring a molten aluminum base alloy containing from about 0.5 to about 0.9 weight percent silicon, about 0.6 to about 0.9 weight percent magnesium and the remainder essentially aluminum into the casting groove of a continuous casting wheel at a temperature above the melting point of the aluminum base alloy; (b) cooling the molten aluminum base alloy in the casting groove to form a cast bar at a rate at which solidification shrinkage will not occur; (c) removing the cast bar from the casting groove at a temperature below 940° F.; (d) continuously hot forming the cast aluminum base metal at a temperature within the hot forming range to form a rod; (e) immediately after the hot forming step and before any substantial cooling of the rod, continuously passing the rod through an in-line heater for approximately five seconds or less to raise the temperature of the rod to a temperature above the temperature at which the alloying metals will precipitate to the grain boundaries of the aluminum base metal; and (f) continuously quenching the rod to a temperature below the temperature level at which immediate substantial precipitation of the alloying metals occur.

Claim 4

A method of continuously casting an aluminum base alloy rod containing from about 0.5 to about 0.9 weight percent silicon, about 0.6 to about 0.9 weight percent magnesium and the remainder essentially aluminum comprising the steps of: (a) pouring a molten aluminum base alloy containing from about 0.5 to about 0.9 weight percent silicon, about 0.6 to about 0.9 weight percent magnesium and the remainder essentially aluminum into the casting groove of a continuous casting wheel at a temperature above the melting point of the aluminum base alloy; (b) cooling the molten aluminum base alloy in the casting groove to form a cast bar at a rate at which solidification shrinkage will not occur; (c) removing the cast bar from the casting groove at a temperature below 940° F.; (d) continuously hot forming the cast aluminum base metal at a temperature within the hot forming range to form a rod; (e) immediately after the hot forming step and before any substantial cooling of the rod, continuously passing the rod through an in-line heater for approximately five seconds or less to raise the temperature of the rod to a temperature above the temperature at which the alloying metals will precipitate to the grain boundaries of the aluminum base metal; and (f) continuously quenching the rod to a temperature below the temperature level at which immediate substantial precipitation of the alloying metals occur.