A Novel Quench-Form and In-Die Creep Age Process for Hot Forming of 2219 Thin Aluminum Sheets with High Precision and Efficiency

This work introduces a novel forming process, named Quench-form and In-die Creep Age (short for QICA). It integrates a hot stamping by warm dies (named quench-form) with a fast in-die creep age to significantly improve the dimensional accuracy of the formed part with maintained post-form mechanical properties and reduced total processing time. The process principle and underlying mechanisms were revealed by experimental forming tests, tensile tests, TEM observations. The optimum processing temperature range has been determined, and the processing window for industrial significance has been discussed. Results showed that under a heat treatment condition of 240 degrees C x 5 min followed by 175 degrees C x 4 h, the panel spring-back is significantly reduced by 75%, from 21 & PRIME; to 5 & PRIME;, compared to that under the T6 forming condition. The total processing time is also dramatically reduced from the conventional 12-4.5 h, increasing the overall production efficiency by 62.5%. From industry perspective, an 80 degrees C temperature operation window, from 160 degrees C to 240 degrees C, is suggested to guarantee a yield strength of > 280 MPa (93% of the T6 strength). The effectiveness of the process has also been verified by forming an aircraft engine inlet lip part. The maximum clearance between the formed part and die was reduced from 7.00 mm to 2.01 mm by replacing the HFQ & REG; technique with the QICA technique. The proposed novel process delivers an alternative energy-efficient method to produce high-accurate extra-large parts that are beneficial for aircraft and aerospace OEMs.