CAREER: Understanding Sensitization and Corrosion Mechanisms in Additively Manufactured Metals for Improved Surface Finish, Mechanical Properties and Corrosion Resistance

职业：了解增材制造金属的敏化和腐蚀机制，以提高表面光洁度、机械性能和耐腐蚀性

• 批准号: 1944516
• 负责人: Owen Hildreth
• 金额: $ 50万
• 依托单位: Colorado School of Mines
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-04-01 至 2025-03-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1944516&HistoricalAwards=false
• 关键词: CAREER; Understanding; Sensitization; Corrosion; Mechanisms

This Faculty Early Career Development (CAREER) grant focuses on identifying, quantifying, and exploiting sensitization and corrosion mechanisms in metals and alloys produced using powder-bed fusion additive manufacturing. Sensitization refers to the precipitation of carbides at grain boundaries in a metal alloy, causing the alloy to be susceptible to intergranular corrosion. Metal additive manufacturing or three-dimensional printing allows companies to manufacture complex parts with improved performance and shorter production times. To reduce the costs of additive manufacturing and expand design freedom, this project establishes the understanding necessary to exploit corrosion phenomena to create a scalable and uniform etching process to dissolve supports and trapped powder while improving surface finish. Specifically, this research project establishes the fundamental relationships between the as-printed microstructure, sensitization kinetics and corrosion mechanisms in these materials. This new understanding allows manufacturers to control the amount of material removed while improving surface finish and mechanical properties. By replacing expensive post-process machining operations with simple chemical dissolution to remove support structures, this new approach reduces manufacturing costs and provides U.S. manufacturing with a competitive advantage. The award’s STEM educational components include curriculum development and K-12 outreach partnerships with groups serving underrepresented minorities and students with disabilities.The specific goal of this research is to understand how the microstructure of powder-bed fusion-processed metals and alloys control sensitization kinetics and corrosion mechanisms. To achieve this understanding, the research objectives of this project are to: (1) understand microstructure evolution during sensitization; (2) understand how the depth-dependent sensitized microstructure changes the corrosion behavior and associated self-terminating etch-stop mechanism; and (3) quantify the impacts that sensitization and dissolution have on mechanical properties and corrosion performance. To achieve these research objectives, this project explores carburization and sulfidation-based sensitization of stainless steel, nickel-based superalloys, and titanium alloys as model systems to test the following hypotheses: (i) carbon-based sensitization depth decreases as the diffusion path for passivating elements increases; (ii) dealloying increases with decreasing diffusion path; and (iii) chromium depletion zone decreases faster with increasing sensitization rate. The overarching focus is to obtain a better understanding of the kinetics of microstructure evolution in high temperature corrosive environments along with increased understanding of the microstructure-dependent corrosion mechanisms in sensitized metals in aqueous environments. This new knowledge is used to guide the design and manufacturing of powder-bed fusion metallic parts towards efficient support structure removal, improved surface finish and increased fracture and fatigue resistance. This project allows the PI to advance the knowledge base in materials science, corrosion, and mechanical behavior while supporting a career in advanced manufacturing.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.

该学院早期职业发展（CAREER）资助的重点是识别、量化和利用粉末床熔融增材制造生产的金属和合金的敏化和腐蚀机制。敏化是指金属合金中碳化物在晶界析出，导致合金容易发生晶间腐蚀。金属增材制造或三维打印使公司能够制造性能更高、生产时间更短的复杂零件。 为了降低增材制造的成本并扩大设计自由度，该项目建立了必要的理解，以利用腐蚀现象来创建可扩展且均匀的蚀刻工艺，以溶解支撑物和捕获的粉末，同时提高表面光洁度。具体来说，该研究项目建立了这些材料中打印的微观结构、敏化动力学和腐蚀机制之间的基本关系。这种新的认识使制造商能够控制去除的材料量，同时提高表面光洁度和机械性能。 通过用简单的化学溶解取代昂贵的后处理加工操作来去除支撑结构，这种新方法降低了制造成本，并为美国制造业提供了竞争优势。 该奖项的 STEM 教育内容包括课程开发以及与为代表性不足的少数群体和残疾学生服务的团体建立 K-12 外展合作伙伴关系。这项研究的具体目标是了解粉末床熔融加工金属和合金的微观结构如何控制敏化动力学和腐蚀机制。 为了实现这一认识，本项目的研究目标是：（1）了解敏化过程中微观结构的演变； (2) 了解深度相关的敏化微观结构如何改变腐蚀行为以及相关的自终止蚀刻停止机制； (3) 量化敏化和溶解对机械性能和腐蚀性能的影响。 为了实现这些研究目标，该项目探索不锈钢、镍基高温合金和钛合金的渗碳和硫化敏化作为模型系统来测试以下假设：（i）碳基敏化深度随着钝化元素扩散路径的增加而减小； (ii) 脱合金随着扩散路径的减小而增加； (iii)随着敏化率的增加，铬贫化区减少得更快。 首要重点是更好地了解高温腐蚀环境中微观结构演化的动力学，同时加深对水环境中敏化金属的微观结构相关腐蚀机制的了解。 这些新知识用于指导粉末床熔融金属零件的设计和制造，以实现有效去除支撑结构、改善表面光洁度并提高抗断裂和抗疲劳能力。该项目使 PI 能够推进材料科学、腐蚀和机械行为方面的知识基础，同时支持先进制造领域的职业生涯。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准进行评估，被认为值得支持。

项目成果

SwiftVISA: Controlling Instrumentation with aSwift-based Implementation of the VISA Communication Protocol

SwiftVISA：通过基于 Swift 的 VISA 通信协议实现来控制仪器

• 发表时间: 2023
• 期刊: Journal of Open Source Software
• 作者: Barnes, Connor;Henke, Luke;Henke, Lorena;Krukov, Ivan;Hildreth, Owen
• 通讯作者: Hildreth, Owen

Iodine-Based Sensitization of Copper Alloys to Enable Self-Terminating Etching for Support Removal and Surface Improvements of Additively Manufactured Components

铜合金的碘基敏化可实现自终止蚀刻，以去除支撑物并改善增材制造组件的表面

• DOI: 10.1089/3dp.2021.0242
• 发表时间: 2022
• 期刊: 3D Printing and Additive Manufacturing
• 影响因子: 3.1
• 作者: Yazdanparast, Sanaz;Raikar, Subbarao;Heilig, Meredith;Hildreth, Owen J.
• 通讯作者: Hildreth, Owen J.

Support Thickness, Pitch, and Applied Bias Effects on the Carbide Formation, Surface Roughness, and Material Removal of Additively Manufactured 316 L Stainless Steel

支撑厚度、节距和施加的偏置对增材制造 316 L 不锈钢碳化物形成、表面粗糙度和材料去除的影响

• DOI: 10.1007/s11837-020-04422-y
• 发表时间: 2020
• 期刊: JOM
• 影响因子: 2.6
• 作者: Hoffman, Robert;Hinnebusch, Shawn;Raikar, Subbarao;To, Albert C.;Hildreth, Owen J.
• 通讯作者: Hildreth, Owen J.

Effect of chemically accelerated vibratory finishing on the corrosion behavior of Laser Powder Bed Fusion 316L stainless steel

• DOI: 10.1016/j.jmatprotec.2022.117596
• 发表时间: 2022-07
• 期刊: Journal of Materials Processing Technology
• 影响因子: 6.3
• 作者: Stephanie Prochaska;O. Hildreth

SwiftVISA: Controlling Instrumentation with a Swift-based Implementation of the VISA Communication Protocol

SwiftVISA：使用基于 Swift 的 VISA 通信协议实现来控制仪器

• 发表时间: 2023
• 期刊: Journal of open source software
• 作者: Barnes, Connor;Henke, Luke;Henke, Lorena;Krokov, Ivan;Hildreth, Owen
• 通讯作者: Hildreth, Owen