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中的敏化和腐蚀机制。敏化是指碳化物在金属合金的晶界处沉淀，导致金属合金中的碳化物沉积。合金容易受到晶间腐蚀。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，该项目建立了这样的认识。具体来说，该研究项目建立了这些材料中打印时的微观结构、敏化动力学和腐蚀机制之间的基本关系。新的理解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去除支撑结构取代昂贵的后处理加工操作，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 教育组成部分包括课程开发以及与服务于代表性不足的少数群体和残疾学生的 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。为了实现这一理解，该项目的研究目标是：（1）了解敏化过程中的微观结构演变；（2）了解深度相关的敏化微观结构如何变化；腐蚀行为和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，该项目探索了不锈钢的渗碳和硫化敏化。 、镍基高温合金和钛合金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的扩散路径而减小增加；（ii）随着扩散路径的减少，脱合金增加；（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变的动力学。这一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。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。该奖项是 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。

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: 2023-03
• 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

Self-terminating etching process for automated support removal and surface finishing of additively manufactured Ti-6Al-4 V

自动终止蚀刻工艺，用于增材制造的 Ti-6Al-4–V 的自动支撑去除和表面精加工

• DOI: 10.1016/j.addma.2020.101694
• 发表时间: 2020-11-07
• 期刊: Additive manufacturing
• 影响因子: 11
• 作者: Subbarao Raikar;Meredith Heilig;Avinash Mamidanna;O. Hildreth
• 通讯作者: O. Hildreth

Sulfidation kinetics of titanium and Ti-6Al-4V with elemental sulfur

钛和Ti-6Al-4V与元素硫的硫化动力学

• DOI: 10.1080/1478422x.2023.2238388
• 发表时间: 2023-08
• 期刊: Science and Technology
• 作者: Raikar, Subbarao;DiGregorio, Steven;Hildreth, Owen J.
• 通讯作者: Hildreth, Owen J.

Improving fatigue performance of additively manufactured Ti-6Al-4V using sulfur-based self-terminating etching processes

使用硫基自终止蚀刻工艺提高增材制造的 Ti-6Al-4V 的疲劳性能

• DOI: 10.1016/j.addma.2022.103331
• 发表时间: 2023-01
• 期刊: Additive Manufacturing
• 影响因子: 11
• 作者: Raikar, Subbarao;DiGregorio, Steven;Agnani, Milan;Hommer, Garrison M.;Hildreth, Owen J.
• 通讯作者: Hildreth, Owen J.

Fatigue and Corrosion Evaluation of L-PBF 316L Stainless Steel Having Undergone a Self-Terminating Etching Process for Surface Finish Improvement

经过自终止蚀刻工艺改善表面光洁度的 L-PBF 316L 不锈钢的疲劳和腐蚀评估

• DOI: 10.1089/3dp.2022.0346
• 发表时间: 2023-07-28
• 期刊: 3D Printing and Additive Manufacturing
• 影响因子: 3.1
• 作者: Stephanie Prochaska;Subbarao Raikar;O. Hildreth
• 通讯作者: O. Hildreth