Top hat door beams were formed from extruded blanks of AA6282, a high-strength, lower-cost alternative to AA7XXX, using 24 different Heating, Forming, Quenching, and Aging (HFQ + A) schedules. The tensile properties (e.g., yield strength, YS; ultimate tensile strength, UTS; strain hardening exponent, \(\overline{{\varvec{n}} }\) ) from coupons extracted from the door beams were then correlated with 3-point bending resistance properties (e.g., maximum bending load, average crush resistance, energy absorption) from 3-point bending tests. A single “optimal” HFQ + A heat treatment was identified as that which resulted in a YS of 396 MPa and UTS of 420 MPa and highest beam bending resistance. In all cases, the bending resistance was found to be strongly positively correlated with YS and UTS, while it is strongly negatively correlated with \(\overline{{\varvec{n}} }\) . Heat treatment effects on microstructure were then correlated with the strain hardening response of the door beams through a combination of Kocks–Mecking (K–M) plots and transmission electron microscopy (TEM). Hardening behavior inferred from the K–M plots was related to dislocation looping and shearing. Precipitates in the low-strength beams fell above the known 2.5 nm transition radius between shearable and non-shearable precipitates (~4.3 nm average precipitate radius); hence, dislocation looping contributes to hardening. Precipitates in the beams with higher strength and bending resistance fell below the transition radius (~1.8 nm average precipitate radius), suggesting dislocation shearing contributes to hardening.
