# US 5,700,424 A · System for preparing aluminum alloy strip having improved formability and bake hardenability > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,700,424 A - Document ID: US5700424A - Status: Granted - Kind: A - Application number: 08/610,547 - Filed: 1996-03-06 - Granted: 1997-12-23 - Earliest claimed: 1996-03-06 - Assignees: Sky Aluminium Co., Ltd. - Inventors: Mamoru Matsuo; Zhu Yan - Web page: https://patentgrep.com/patent/US5700424A ## CPC - C22F 1/05: of alloys of the Al-Si-Mg type, i.e. containing silicon and magnesium in approximately equal proportions - C21D 9/56: Continuous furnaces for strip or wire - C22F 1/043: of alloys with silicon as the next major constituent - C22F: CHANGING THE PHYSICAL STRUCTURE OF NON-FERROUS METALS AND NON-FERROUS ALLOYS (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass, C23F17/00) - C21D: MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING (surface treatment of metallic material involving at least one process provided for in class C23 and at least one process covered by this subclass C23F17/00; unidirectional solidification of eutectic materials or unidirectional demixing of eutectoid materials C30B) ## Abstract A system for heat treating a rolled strip of Al--Mg--Si alloy includes a primary heating zone for solution treating the strip at 480.degree. C. or higher, a first cooling zone for cooling the strip at a rate of at least 100.degree. C./min. to 100.degree. C. or lower, a secondary heating zone for heating the strip to 120.degree.-250.degree. C. within 10 minutes for thereby adjusting a proof stress of 70-120 N/mm.sup.2 directly or after holding for 10 minutes or less, a coiler for winding the strip into a coil at 140.degree. C. or lower, and a unit for holding the coil at 50.degree.-140.degree. C. for at least 3 hours. The process from solution treatment to winding is continuous as well as from winding to stabilizing treatment. The strip has improved formability and bake hardenability and a minimized secular change at room temperature. ## Claims ### Claim 1 A system for preparing an aluminum alloy strip having improved formability and bake hardenability and a minimized secular change at room temperature, the aluminum alloy consisting essentially of in % by weight, 0.3 to 1.5% of Mg, 0.5 to 2.5% of Si, and the balance of aluminum, said system comprising means for continuously unraveling a rolled strip of the aluminum alloy from its coil, a continuous heat treatment section for continuously receiving the rolled strip from said unraveling means, heat treating it, and delivering it outward, means for continuously winding up the rolled strip exiting from the continuous heat treatment section into a coil form, and means for holding the coil of rolled strip at a temperature in the range of 50.degree. to 140.degree. C. for at least 3 hours, said continuous heat treatment section including a first accumulator for continuously receiving the strip from said unraveling means and feeding it downstream, a primary heating zone disposed downstream of said first accumulator for continuously receiving the strip therefrom and heating it to a temperature of at least 480.degree. C., a first cooling zone disposed downstream of said primary heating zone for continuously receiving the strip therefrom and cooling it at a rate of at least 100.degree. C./min. to a temperature of not greater than 100.degree. C., and a secondary heating zone disposed downstream of said first cooling zone for continuously receiving the strip therefrom and heating it to a temperature in the range of 120.degree. to 250.degree. C. within 10 minutes from the end of cooling. ### Claim 2 (depends on 1) The system of claim 1 wherein said continuous heat treatment section further includes a second cooling zone disposed downstream of said secondary heating zone for continuously receiving the strip therefrom and cooling it to a temperature of not greater than 140.degree. C. ### Claim 3 (depends on 2) The system of claim 2 wherein said continuous heat treatment section further includes a second accumulator disposed downstream of said second cooling zone for continuously receiving the strip therefrom and feeding it to said winding means. ### Claim 4 (depends on 1) The system of claim 1 wherein said continuous heat treatment section further includes a second accumulator disposed between said first cooling zone and said secondary heating zone for continuously transferring the strip therebetween such that the strip may travel through said second accumulator for a residence time within 10 minutes. ### Claim 5 (depends on 1) The system of claim 1 wherein said holding means includes a holding furnace for holding the coil of rolled strip being wound up in said winding means at a temperature in the range of 50.degree. to 140.degree. C. ### Claim 6 (depends on 1) The system of claim 1 wherein said holding means includes means for continuously or intermittently conveying the coil of rolled strip forward while heating it at a temperature in the range of 50.degree. to 140.degree. C. such that the residence time within the temperature range is at least 3 hours. ### Claim 7 (depends on 1) The system of claim 1 wherein the aluminum alloy further contains at least one element selected from the group consisting of 0.03 to 1.2% of Cu, 0.03 to 1.5% of Zn, 0.03 to 0.4% of Mn, 0.03 to 0.4% of Cr, 0.03 to 0.4% of Zr, 0.03 to 0.4% of V, 0.03 to 0.5% of Fe, and 0.005 to 0.2% of Ti .