High Speed Friction Stir Spot Welding: A New Approach to Spot Joining of Ultra High Strength Steel

高速搅拌摩擦点焊：超高强度钢点焊的新方法

• 批准号: 1131203
• 负责人: Michael Miles
• 金额: $ 26万
• 依托单位: Brigham Young University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-09-01 至 2015-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1131203&HistoricalAwards=false
• 关键词: Speed; Friction; Stir; Spot; Welding

The research objective of this award is to test the hypothesis that joint bond area in friction stir spot welding of ultra-high strength steel is determined largely by interface pressure, interface temperature, and weld time. Welding speeds in the range of 5,000 to 10,000 revolutions per minute will be considered, and the welding process will be constrained to a maximum vertical welding load of eight kilonewtons, with a goal of achieving a desired level of joint strength. A novel approach to modeling friction stir spot welding will be used within a Lagrangian finite element framework, where the joint interface will be represented virtually and where a proposed relationship between joint contact pressures, temperatures, and weld time will be used to estimate bond area. Archard's law will be used within the model to estimate tool wear. An experimental program will measure joint strength and tool wear over time, while microstructural evaluation of the joints will provide insight into the effect of tool wear on bonding mechanisms.If successful, this project will enable the use of friction stir spot welding for joining ultra-high strength steel sheet in many industrial settings. The modeling approach will provide increased understanding of the role of tool design and process conditions on joint strength and tool life. Finding a solution to spot joining of ultra-high strength steels is important because these alloys have the potential to make car frames lighter and stiffer, improving vehicle fuel economy and reducing carbon emissions. The widespread use of ultra-high strength steel is currently limited by brittle weld microstructures produced by traditional resistance spot welding.

该奖项的研究目的是检验超高强度钢搅拌摩擦点焊中接头结合面积主要由界面压力、界面温度和焊接时间决定的假设。将考虑每分钟 5,000 至 10,000 转范围内的焊接速度，并且焊接过程将被限制在最大垂直焊接载荷 8 千牛顿，目标是达到所需的接头强度水平。将在拉格朗日有限元框架内使用一种新颖的搅拌摩擦点焊建模方法，其中将虚拟地表示接头界面，并使用接头接触压力、温度和焊接时间之间的拟议关系来估计粘合面积。阿查德定律将在模型中用于估计刀具磨损。实验计划将测量接头强度和工具随时间的磨损，而接头的微观结构评估将深入了解工具磨损对粘合机制的影响。如果成功，该项目将能够在许多工业环境中使用搅拌摩擦点焊来连接超高强度钢板。建模方法将加深人们对工具设计和工艺条件对接头强度和工具寿命的作用的理解。找到超高强度钢点焊的解决方案非常重要，因为这些合金有可能使汽车框架更轻、更坚固，从而提高车辆燃油经济性并减少碳排放。目前，超高强度钢的广泛使用受到传统电阻点焊产生的脆性焊缝微观结构的限制。