Design and Fabrication of Graded Materials with the Laser Engineered Net Shaping Process

采用激光工程净成形工艺设计和制造梯度材料

• 批准号: 0758622
• 负责人: John DuPont
• 金额: $ 29.5万
• 依托单位: Lehigh University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2012-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0758622&HistoricalAwards=false
• 关键词: Design; Fabrication; Graded; Materials; Laser

The objective of this research is to develop methods for designing and fabricating graded transition joints for avoiding failures in dissimilar welds. The graded transition joints will consist of gradual and controlled changes in composition and resultant properties. This will significantly reduce or eliminate failures in dissimilar welds that are currently caused by very sharp changes in composition and properties. The optimal gradation in properties will first be determined using structural optimization routines. This information will then be utilized to fabricate various graded transition joints using microstructural modeling and the Laser Engineered Net Shaping (LENS) process. The performance of these joints will be evaluated relative to the industry standard joints using a variety of techniques, including light/electron microscopy, microhardness testing, high temperature tensile testing, and creep-rupture analysis. Optimal graded joints will then be installed into the power plants of the industrial partner along with conventional joints for side-by-side field testing.The need to join dissimilar materials is expected to increase as more demand is placed on the performance of materials under conditions of increasing stress, temperature, and corrosive environment. Graded materials offer significant potential for joining dissimilar materials, but methods for designing these joints for improved performance are not yet available. In addition, dissimilar weld failures currently carry significant economic impact. For example, a single dissimilar weld failure can cost an electric power company up to $850,000/day in down time and lost revenue. If successful, the results of this research will lead to development of methods for optimizing the design, fabrication, and performance of graded materials that can be used in a variety of applications. The results will also lead to an improved understanding of the complex relationships between processing, structure, and properties in LENS processing. Lastly, the direct implementation of the technology for joining dissimilar materials in power generation applications will provide significant cost savings by eliminating dissimilar weld failures.

本研究的目的是开发设计和制造分级过渡接头的方法，以避免异种焊缝失效。 分级过渡接头将由成分和最终性能的逐渐且受控的变化组成。这将显着减少或消除目前由于成分和性能急剧变化而导致的异种焊缝故障。首先将使用结构优化例程确定最佳的性能等级。然后，该信息将用于使用微结构建模和激光工程净成形 (LENS) 工艺来制造各种分级过渡接头。这些接头的性能将使用各种技术相对于行业标准接头进行评估，包括光学/电子显微镜、显微硬度测试、高温拉伸测试和蠕变断裂分析。然后，最佳分级接头将与传统接头一起安装到工业合作伙伴的发电厂中，进行并排现场测试。随着对材料在条件下的性能提出更多要求，预计连接异种材料的需求将会增加不断增加的应力、温度和腐蚀环境。分级材料为连接不同材料提供了巨大的潜力，但设计这些接头以提高性能的方法尚不可用。此外，异种焊接故障目前会带来重大的经济影响。例如，一次异种焊接故障可能会导致电力公司每天因停机和收入损失而损失高达 850,000 美元。如果成功，这项研究的结果将导致开发优化可用于各种应用的分级材料的设计、制造和性能的方法。研究结果还将有助于更好地理解 LENS 加工中加工、结构和属性之间的复杂关系。最后，在发电应用中直接实施连接异种材料的技术将通过消除异种焊接故障来显着节省成本。