The bumper beam is an important device to ensure the safety of the car, which can effectively alleviate the force and absorb energy when the car collides. Traditional bumper beams are mostly made of high-strength steel, which has high strength and a low production cost but a heavy weight. With the requirement of being lightweight, high-strength steel is not able to meet the needs of lightweight cars, and composite materials have become the answer to the problem of a light weight in cars due to their excellent performance of being lightweight and high strength. This article introduces the case study on materials of bumper beams and presents the application of traditional materials and composite materials in bumper beams. Then, the fabrications and processes of bumper beams, a performance assessment, experimental tests, and a finite element analysis of the bumper beam are carried out. This paper also represents the study of optimization in automobile bumper beams.

In recent years, the widespread application of Mg alloy casting and Mg alloy products has generated a large amount of Mg alloy waste. This experiment used a single factor experimental analysis method to study the optimal process for removing Fe from Mg alloy AM50A waste, and developed an efficient Fe removal and regeneration process for Mg alloy AM50A. It was found that the optimal refining temperature for removing Fe ions was 670 °C, the optimal refining (RJ-2) agent mass ratio was 1.5%, and the optimal refining time was 40 min. Regenerated J40-1.5-AM50A Mg alloy was prepared using the best refining process, and its composition and mechanical properties were tested and analyzed. The experimental results show that the composition of the regenerated J40-1.5-AM50A Mg alloy prepared by this method is consistent with AM50A, with an Fe removal rate of 96.2%. The mechanical properties were improved compared to the original AM50A sample, with a maximum tensile strength increase of 1.611 KN and a tensile strength increase of 26.333 MPa. The elongation after fracture is 2.25 times that of the original sample. Research has shown that the RJ-2 refining agent can provide mechanical properties of magnesium alloys during the refining process. By analyzing the composition, XRD, SEM, and EDS of AM50A (Fe) and J40-1.5-AM50A, it was found that the refining process accelerates the removal of Fe in the form of Fe deposition.

Fe-rich phases are unavoidable intermetallic compounds in aluminum alloys, particularly in recycled aluminum. Their needle-like morphology not only impairs the mechanical performance of the alloy by disrupting the continuity of the matrix but also significantly reduces the allowable addition of recycled aluminum materials. Based on this, this study focuses on the Al-7Si-0.35Mg-0.35Fe alloy with a high Fe content. The Cr was introduced to modify the characteristics of the Fe-rich phase, and the microstructural evolution and mechanical properties of the aluminum alloy with different Cr content (0–0.25 wt.%) were investigated. Experimental results show that the secondary dendrite arm spacing of the alloy is significantly refined after Cr addition. Meanwhile, the Fe-rich phase gradually transitions from β-Al₅FeSi with needle-like morphology to α-Al₁₅(Fe,Cr)₃Si₂ with short rod-like or blocky morphology as the Cr content increases. Notably, the Fe-rich phase in the 0.20Cr alloy exhibits an approximately 65% increase in sphericity and an 84% reduction in equivalent diameter compared to those in the 0Cr alloy. The morphological blunting and dispersed distribution of Fe-rich phases lead to a broad effective Cr addition range of 0.05–0.20 wt% in the alloy. Among them, the 0.20Cr alloy exhibited the best comprehensive mechanical properties, with its ultimate tensile strength and elongation approximately 19% and 107% higher than those of the 0Cr alloy, respectively. Furthermore, the fracture morphology and the relationship between the Fe-rich phase and microcracks in Al-7Si-0.35Mg-0.35Fe alloys with different Cr contents were also analyzed.

Against the backdrop of continuously expanding global magnesium alloy applications and surging scrap generation, achieving efficient recycling and low-carbon regeneration of magnesium alloys has emerged as a key pathway for advancing green transformation in manufacturing. The AM50A recycled magnesium alloy was selected as the research subject, employing the attributional life cycle assessment (ALCA) methodology to systematically calculate its “cradle”-to-“gate” carbon footprint across three stages: raw material acquisition, transportation, and production. The results indicate that the carbon footprint of AM50A recycled magnesium alloy is 4.9399 kg CO₂e/kg, with the production stage accounting for a significant 99.34% of emissions, identified as the primary source. The combined contribution from raw material acquisition and transportation stages is only 0.66%. Compared to magnesium alloys produced by the Pidgeon process, greenhouse gas (GHG) emissions can be reduced by approximately 67.56% through the recycling process, highlighting its significant advantages in promoting low-carbon manufacturing and circular economic development for magnesium alloys. This study provides data support for the environmental performance assessment of recycled magnesium alloys and offers a scientific basis for optimizing energy conservation and emission reduction pathways in related industries.

With the tightening of energy consumption and emission regulations, automotive lightweight is more and more imperative. Herein, A-pillar upper reinforcement using 1700 MPa ultra-high strength steel (UHSS) 3D roll bending was firstly designed and applied to carbon fiber reinforced plastics (CFRP) side frame to achieve extreme lightweight and collision safety performance. The load extraction and subsystem model structure optimization methods were developed to solve the problems of large analysis model and low calculation efficiency in the traditional optimization iteration process. Finally, the application of 1700 MPa UHSS 3D-roll bending A-pillar upper reinforcement onto the CFRP side frame can reduce the weight by 19%, and improve the collision performance effectively.