The softening of aluminum–lithium alloy welded joints generally leads to a reduction in mechanical properties. In this study, a piece of 2A97-T3 aluminum–lithium alloy with a thickness of 2.8 mm was selected as the test material, and the tool and process used for wire-filled stationary shoulder friction stir welding (SSFSW) were developed. By increasing the bearing area of the softening zone, an equal-strength T-joint was manufactured. Good weld formation was obtained when the rotation speed was set to 2000 rpm and the welding speed ranged from 100 to 120 mm/min. The thickness of the softening zone was controlled by adjusting the reserved gap between the shoulder and the workpiece. The softening mechanism of the weld joint was revealed. The softening was attributed to the coarsening of the main precipitated phases (T1 and θ′ phases) in the heat-affected zone (HAZ) and the dissolution of precipitated phases in the thermo-mechanically affected zone (TMAZ). Grain refinement in the nugget zone (NZ) led to a certain fine-grained strengthening effect, although the precipitated phase was almost completely dissolved. Due to the thermal effect of second-pass welding, the hardness value of the NZ and HAZ in the center of the skin further decreased, and the minimum hardness was approximately 70% that of the base material. Tensile testing results indicated that the softening effect was largely offset by the increased bearing area of the softening zone, resulting in the successful welding of high-strength Al-Li alloy T-joints with equal strength. The strength coefficient was found to be 0.977.

The formulation of robust Welding Procedure Specifications (WPS) is paramount in aviation manufacturing, where quality directly impacts structural integrity and flight safety. Current practices, however, often rely on experiential knowledge and lack a systematic methodology for balancing performance, reliability, and economy, leading to unstable product quality and limited forward-design capability. This study addresses these gaps by proposing a novel, three-layer structural model for aviation WPS based on trade-off design principles. The model integrates a comprehensive correlation matrix linking product requirements to process elements, a modular architecture for enhanced reusability, and a knowledge-driven validation workflow. A key feature of the validation method is the use of a scientifically designed process test matrix and Statistical Process Control (SPC) to quantitatively determine process margins and capability indices (Cv, Cpk), moving beyond traditional pass/fail criteria. The application of this methodology is demonstrated and validated through a case study on electron beam welding. The results indicate that the proposed framework provides a systematic approach for developing stable, economical, and digitally ready welding process specifications, thereby significantly improving the forward-design capability in aviation welding.

A comparative investigation of the corrosion behavior evolution of 15%SiCp/Al-Cu-Mg aluminum matrix composites (AMC) subjected to different heat treatments in a salt spray environment containing 5wt% NaCl was performed. Metallographic microscopy was used to observe the surface morphology of the corroded materials. Field-emission transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for microstructural evaluation and elemental analysis of the samples. Polarization curves and electrochemical impedance spectroscopy (EIS) were also employed to investigate the corrosion performance of the particle-reinforced aluminum matrix composites under different heat treatments. The test results indicate that, in addition to the influence of various grain boundary precipitates and electrochemical inhomogeneities between the precipitate-free zone (PFZ) and the aluminum matrix, differences in electrochemical properties between the SiC reinforcement particles and the aluminum alloy matrix are also a primary factor contributing to the corrosion of the aluminum-based composites in a 5wt% NaCl salt spray environment. Microstructural observations and electrochemical testing of AMC specimens at different corrosion stages indicate that under-aged samples exhibit relatively higher intergranular corrosion susceptibility. Under prolonged exposure to a salt spray environment, the over-aged specimen exhibited more pronounced galvanic corrosion phenomena, specifically, a significant decrease in Charge transfer resistance (R_ct) values and an increase in CPE values. R_ct results indicate that naturally aged AMC exhibits higher corrosion resistance than artificially aged AMC. With increased salt spray corrosion time, varying degrees of crevice corrosion occurred at the Al–SiC interface in all heat-treated samples.

Aviation products demand exceptionally high safety standards, where welding quality directly impacts structural integrity and flight safety. Welded joints must possess high strength and fatigue resistance. Since the welding process cannot be fully inspected and is classified as a special process, its manufacturing and production procedures require strict control, making the completeness of process specifications particularly crucial. Currently, the formulation of welding process specifications primarily relies on the production experience of process designers, with excessive focus on equipment processing parameters. This often leads to unstable product quality during production and fails to provide valuable references for aircraft structural designers. To enhance the performance, stability, and cost-effectiveness of Aviation welded products, this paper thoroughly considers the design requirements for welded products. It analyzes the full spectrum of elements within process specifications based on trade-off design. A structural model for welding process specifications is proposed, and a knowledge-driven methodology for standard verification and determining critical indicators is investigated. Using a laser welding production process as a case study, the structural model for Aviation product welding process specifications is validated.