Key Takeaways & Executive Findings
- •• Forced cooling during friction stir welding significantly enhances the corrosion resistance of fine-grained Al7075 joints, with the stir zone exhibiting the highest resistance. • The improvement is attributed to refined grain structure, increased Σ3 grain boundaries, and a denser oxide layer formation. • Forced cooling reduces the precipitation and coarsening of anodic phases, lowering susceptibility to pitting corrosion. • Lower recrystallization texture content decreases corrosion-active sites, further improving corrosion performance.
Abstract
This work examines the microstructure and corrosion properties of fine-grained Al7075 across different regions under varying cooling conditions during friction stir welding. The findings demonstrate that forced cooling significantly improves the corrosion resistance of the welded joints. Specifically, the corrosion resistance was the highest in the stir zone, followed by the thermo-mechanical affected zone, and then the heat affected zone. Forced cooling mitigates grain growth by controlling the welding thermal effects, thereby increasing the proportion of Σ3 grain boundaries. The modification of these microstructural characteristics promotes the formation of a dense oxide layer, thereby enhancing the corrosion resistance. Furthermore, forced cooling mitigates the precipitation and coarsening of the anodic phase in the stir zone, which in turn reduces the susceptibility of the joint to pitting corrosion. Additionally, the lower recrystallization texture content in the joint, resulting from forced cooling, contributes to a reduction in the number of corrosion-active sites, thereby further improving the corrosion performance of the welded joint.
1. Introduction
Aluminum alloy 7075 (Al7075) is widely used in aerospace and transportation industries due to its exceptional specific strength, specific stiffness, and superior mechanical properties under dynamic loading conditions [1−4]. Its characteristics of deformable heat treatment strengthening and low density make it indispensable in lightweight structural applications [5−7]. However, with the continuous advancement of modern transportation systems requiring optimized load-bearing capacity and stringent weight reduction, there is an urgent need to enhance the mechanical properties of Al7075 alloy. Under the Hall-Petch relationship, grain refinement strengthening has become a key strategy for simultaneously improving both yield strength and fracture toughness.
However, fine-grained Al7075 exhibits poor thermal stability, making it difficult to weld and limiting its widespread application. Friction stir welding (FSW), as a mature solid-state welding technology, involves temperature, mechanical, metallurgical, and interaction processes [6, 8]. Due to its energy efficiency, environmental friendliness, and excellent joint quality, FSW has become a revolutionary welding technique [9, 10]. Compared to conventional welding methods, FSW offers the advantage of low heat input (with the possibility of additional cooling media, such as water or air cooling), making it an effective method for joining fine-grained materials while preserving their strength and toughness. Previous research by LUO et al [11] indicated that during the FSW process of fine-grained Al7075, forced cooling (FC) preserved the fine-grained microstructure of the joint and maintained the strengthening effect achieved prior to welding.
Loading authentic research manuscript (Pages 1–5)...
Yang Bo-hai, Luo Lei, Wang Wen, Cui Chun-juan, Yang Xi-rong, Gan Chen, Yan Wen-wen, Han Ying (2026). Influence mechanism of cooling strategy on the improvement of corrosion performance of fine-grained Al7075 friction stir welding joint. Journal of Central South University. https://doi.org/10.1007/s11771-026-6160-2
Research & Educational Purpose Only:The translations, structured abstracts, analytical annotations, and data reports provided by SinoTechIntel are intended exclusively for academic research, internal corporate R&D, and educational benchmarking. They do not constitute formal engineering, chemical safety, legal, or professional advice.
Copyright & Intellectual Property Notice: Original copyright of the underlying source articles and experimental data remains with the respective authors, institutions, and original publishing journals. SinoTechIntel claims intellectual property only over its proprietary translations, analytical syntheses, and AEO structured enhancements in accordance with international fair use and academic citation principles.
Frequently Asked Questions
What is the effect of forced cooling on the corrosion resistance of Al7075 FSW joints?
Forced cooling significantly improves the corrosion resistance of fine-grained Al7075 friction stir welding joints by refining the grain structure, increasing the proportion of Σ3 grain boundaries, and promoting the formation of a dense oxide layer. It also reduces the precipitation and coarsening of anodic phases, thereby lowering susceptibility to pitting corrosion.
Which zone of the welded joint exhibits the highest corrosion resistance?
The stir zone (SZ) exhibits the highest corrosion resistance, followed by the thermo-mechanical affected zone (TMAZ) and then the heat affected zone (HAZ).
How does forced cooling affect the microstructure of the joint?
Forced cooling mitigates grain growth by controlling welding thermal effects, leading to a finer grain structure and an increased proportion of Σ3 grain boundaries. It also reduces the recrystallization texture content, which contributes to fewer corrosion-active sites.
Why is Al7075 alloy difficult to weld?
Fine-grained Al7075 exhibits poor thermal stability, making it difficult to weld using conventional methods. Friction stir welding, especially with forced cooling, is an effective technique to join this alloy while preserving its fine-grained microstructure and mechanical properties.
What are the practical implications of this research?
The findings provide insights into optimizing cooling strategies during friction stir welding to enhance the corrosion performance of Al7075 joints, which is critical for applications in marine and aerospace environments where corrosion resistance is essential.
Related Technical Papers & Translations
Direct Repair of the Crystal Structure and Coating Surface of Spent LiFePO4 Materials Enables Superfast Li-Ion Migration
The rapid accumulation of spent LiFePO4 (LFP) cathodes from retired lithium-ion batteries necessitates the development of effective and environmental-friendly recycling strategies. In this context, direct regeneration has emerged as a promising approach for reclaiming LFP cathode materials, offering a streamlined pathway to restore their electrochemical functionality. We report an integrated regeneration protocol that simultaneously repairs the degraded crystal structure and reconstructs the damaged carbon coating in spent LFP. The regenerated cathode material had superfast lithium-ion diffusion kinetics and a stable cathode–electrolyte interface, giving a remarkable rate capability with specific capacities of 122 mAh g−1 at 5C and 106 mAh g−1 at 10C (1C = 170 mA g−1). It also maintained capacities of 110.7 mAh g−1 (5C) and 84.1 mAh g−1 (10C) after 400 cycles. It could be used in harsh environments and could be stably cycled at subzero temperatures (−10 and −20 °C) and in solid-state electrolyte batteries. Life cycle assessment combined with economic evaluation using the EverBatt model reveals that this direct regeneration approach has high economic and environmental benefits.
Oxide Semiconductor for Advanced Memory Architectures: Atomic Layer Deposition, Key Requirement and Challenges
Oxide semiconductors (OSs), introduced by the Hosono group in the early 2000s, have evolved from display backplane materials to promising candidates for advanced memory and logic devices. The exceptionally low leakage current of OSs and compatibility with three-dimensional (3D) architectures have recently sparked renewed interest in their use in semiconductor applications. This review begins by exploring the unique material properties of OSs, which fundamentally originate from their distinct electronic band structure. Subsequently, we focus on atomic layer deposition (ALD), a core technique for growing excellent OS films, covering both basic and advanced processes compatible with 3D scaling. The basic surface reaction mechanisms—adsorption and reaction—and their roles in film growth are introduced. Furthermore, material design strategies, such as cation selection, crystallinity control, anion doping, and heterostructure engineering, are discussed. We also highlight challenges in memory applications, including contact resistance, hydrogen instability, and lack of p-type materials, and discuss the feasibility of ALD-grown OSs as potential solutions. Lastly, we provide an outlook on the role of ALD-grown OSs in memory technologies. This review bridges material fundamentals and device-level requirements, offering a comprehensive perspective on the potential of ALD-driven OSs for next-generation semiconductor memory devices.
Laser powder bed fusion of biodegradable Zn-4Cu alloy: Processing, microstructure and properties
Zn's natural degradability and biocompatibility make it a promising candidate for implants, however, its mechanical properties remain insufficient for bone applications. In this study, the performance of Zn was enhanced by developing Zn-Cu alloys via laser powder bed fusion (LPBF). Optimal LPBF parameters for forming stable tracks were achieved by adjusting laser power and scanning speed. Under optimized conditions of 100 W and 100 mm/s, high-density (99.58%) Zn-Cu alloys with improved hardness (68.2HV) and yield strength (160 MPa) were achieved. These improvements are attributed to solid solution strengthening, segregation strengthening, and grain refinement. The Zn-Cu alloys also demonstrated favorable degradation behavior, with a rate of 0.16 mm/year. This degradation is primarily driven by micro-galvanic corrosion between the CuZn5 phase and Zn matrix, along with refined grains and increased grain boundary density. This work demonstrates a viable strategy for fabricating Zn-based implants with enhanced structural integrity and mechanical performance via LPBF.