Room temperature aging suppression and manufacturing methods and aluminum alloy panel material for automobiles of excellent automotive aluminum alloy panel material in low-temperature aging hardenability

摘要

PROBLEM TO BE SOLVED: To provide a method for producing an Al alloy material of excess Si type 6000 based Al in which room temperature aging is suppressed, and which further has excellent low temperature age hardenability, and combines various characteristics such as press formability, hem workability, corrosion resistance and weldability as well, and the Al alloy material.;SOLUTION: An Al-Mg-Si based aluminum alloy material having a composition containing 0.4 to 1.3% Si, 0.4 to 1.2% Mg, 0.01 to 0.65% Mn and 0.001 to 1.0% Cu, and in which Si/Mg is ≥1, is subjected to solution treatment and quenching treatment at 500 to 550°C, is thereafter directly subjected to preaging treatment of holding it in the range of 50 to 100°C, is further subjected to subaging treatment of holding it in the range of 80 to 120°C. As the characteristics after room temperature aging for at least 4 months after the subaging treatment of the aluminum alloy material, electric conductivity is controlled to the range of 41 to 47.5 IACS% and also to -0.125 σ0.2+61.4 or higher (wherein, σ0.2 is the proof stress after the room temperature aging for at least 4 months after the subaging treatment), the proof stress is controlled to the range of 110 to 160 MPa, also, the difference in the proof stress with that directly after the subaging treatment is controlled to ≤15 MPa, its elongation is controlled to ≥28%, and further, the proof stress in low temperature aging treatment at 150°C for 20 min after the application of a stretch of 2% is controlled to ≥180 MPa.;COPYRIGHT: (C)2002,JPO