Fundamental Study on Nanotechnology Enabled Arc Welding of High Strength Aluminum Alloys

高强度铝合金纳米技术电弧焊基础研究

• 批准号: 2230828
• 负责人: Xiaochun Li
• 金额: $ 38.07万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2230828&HistoricalAwards=false
• 关键词: Fundamental; Study; Nanotechnology; Enabled; Arc

This project seeks to advance the fundamental understanding of nanoparticle-enabled mechanisms for enhancing arc weldability of high strength aluminum alloys. Due to their exceptional mechanical performance, high strength aluminum alloys are desired for numerous structural applications. For example, incorporating lightweight structural components into functional assemblies by welding is critical to reduce fuel consumption and emissions for transportation applications. However, most of these high strength alloys are difficult to weld because of cracking, which significantly hinders their widespread use. Recently a nanotechnology enabled welding approach involving adding nanoparticles to the molten weld pool has been experimented with to improve arc welding of aluminum alloys, but lack of control and poor fundamental understanding have hindered its practical use. In this project, a novel nanotechnology-enabled arc welding process, involving a specially fabricated nanocomposite feed wire, is studied to overcome the problem of poor weldability of high strength aluminum alloys. This facilitates the manufacture of large-scale, light-weight structures and components for aerospace, automotive and biomedical applications, thus impacting US industry and enhancing National prosperity. This project has rich educational, training, and outreach components, including new curriculum developments, diverse K-12 and university student involvement, outreach, and technology transfer activities. The goal of this research is to understand how nanoparticles enhance weldability and eliminate hot cracking during arc welding of high strength aluminum alloys. Hot cracking in arc welds occurs due to thermal stresses, columnar growth and incomplete backfilling. For this research Al-Zn-Cu-Mg (AA7075) is used as the model aluminum alloy while gas tungsten arc welding (GTAW) as the model welding process. The project first focusses on the fabrication of nanocomposite consumable wires via extrusion and wiredrawing of ingots cast by a flux-assisted liquid-state nanoparticle incorporation and dispersion process. Next, both experimental and analytical studies are conducted to understand how nanoparticles influence the solidification behavior of AA7075 during arc welding. Standard crack susceptibility testing, microstructural study, and thermal analysis during the solidification process are performed. The research involves examining how nanoparticles affect the solidification time of the melting zone, liquid fraction during solidification, and refinement/modification of both primary and secondary phases. The project studies how nanoparticles induce changes in thermal flow and liquid fraction throughout the welded material, influence the solidification behavior and eliminate hot cracks. The project characterizes nanoparticle effects on weld microstructures and mechanical properties, establishes process-microstructure-property correlations and generates new knowledge for nanoparticle effects on weldability during arc welding of traditionally hard-to-weld aluminum alloys.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

该项目旨在促进对纳米颗粒机制的基本理解，以提高高强度铝合金的电弧可焊性。由于其优异的机械性能，高强度铝合金在许多结构应用中都是需要的。例如，通过焊接将轻质结构部件整合到功能组件中对于减少运输应用的燃料消耗和排放至关重要。然而，这些高强度合金大多由于开裂而难以焊接，这极大地阻碍了它们的广泛应用。最近，人们尝试了一种纳米技术焊接方法，即在熔池中加入纳米颗粒来改善铝合金的电弧焊，但缺乏控制和缺乏基础知识阻碍了其实际应用。在本项目中，研究了一种新的纳米技术支持的弧焊工艺，包括特殊制备的纳米复合馈线，以克服高强度铝合金的可焊性差的问题。这有助于制造用于航空航天、汽车和生物医学应用的大型、轻质结构和部件，从而影响美国工业并促进国家繁荣。该项目具有丰富的教育、培训和推广内容，包括新课程开发、多样化的K-12和大学生参与、推广和技术转让活动。本研究的目的是了解纳米颗粒如何提高高强度铝合金弧焊的可焊性和消除热裂。热裂纹是由于热应力、柱状生长和充填不完全引起的。本研究采用Al-Zn-Cu-Mg （AA7075）作为模型铝合金，采用钨极气体保护焊（GTAW）作为模型焊接工艺。该项目首先关注的是通过挤压和拉丝的方式，通过助熔剂辅助液态纳米颗粒掺入和分散工艺铸造锭，制造纳米复合材料消耗线。接下来，进行了实验和分析研究，以了解纳米颗粒如何影响AA7075在电弧焊过程中的凝固行为。在凝固过程中进行了标准裂纹敏感性测试、显微组织研究和热分析。该研究包括研究纳米颗粒如何影响熔点的凝固时间、凝固过程中的液体分数以及一次相和二次相的细化/改性。该项目研究纳米颗粒如何诱导焊接材料的热流和液体分数的变化，影响凝固行为并消除热裂纹。该项目描述了纳米颗粒对焊缝显微组织和力学性能的影响，建立了工艺-显微组织-性能的相关性，并为传统难焊铝合金的弧焊中纳米颗粒对可焊性的影响提供了新的知识。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。