Microstructural Impact on the Machinability of Titanium Alloys

钛合金具有轻质和高强度的优异组合，因此对于许多工程应用是理想的。在最终生产之前，大多数钛零件必须经过机械加工过程，这通常是困难和昂贵的。钛部件和机床的损坏是常见的，但人们对导致这种损坏的原因以及如何控制这种损坏知之甚少。该奖项支持基础研究，以调查钛合金零件加工过程中的变形和磨损机制。合金的非常精细的结构对于确定钛加工中刀具磨损，切削行为和分段切屑的根本原因具有重要意义，并且了解这种结构和加工之间的基本关系将使研究人员能够建立所需的知识来确定切削刀具设计策略并优化合金结构以获得更好的可切削性，并预测部件的性能。这些新知识将在许多制造业中具有广泛的适用性，包括航空航天，汽车和基础设施。此外，该奖项还将带来强大的教育效益，包括为学生提供最先进的研究项目的多样化机会和经验。这个跨学科团队将汇集机械工程和材料科学的研究人员，对钛合金微观结构的差异如何影响可加工性指标进行基本了解。钛合金的微观结构非常复杂，大多数合金（包括最常见的商业使用的合金Ti-6Al-4V）具有两种不同的相：各向异性的六方密堆积（HCP）相和更各向同性的体心立方（BCC）相。由于先前的成形和热处理工艺，两种相在各种形态和纹理中的许多组合是可能的。这项工作将调查加工前的微观结构如何影响可加工性指标，如切屑分割，刀具磨损，过程动力学和成品的表面完整性。这项工作的目的是确定和量化的钛微观结构和这些机械加工性指标之间的相互作用。一个成功的结果将导致基于科学的见解和合理的工具和切削参数的选择，调整到合金的微观结构和成分，并导致加工部件具有高的结构完整性。这些新知识将使我们能够描述和预测许多观察到的现象，如切削刀具上的微切屑、分段切屑和高切削速度下的刀具过度磨损。 这将导致合理的方法，以降低整体加工成本，通过优化材料规格的可加工性和产品性能，以及确定改进的方法来机加工钛合金。

Titanium alloys have an excellent combination of light weight and high strength, and thus are desirable for a number of engineering applications. Before final production, most titanium parts must undergo a machining process, which is often difficult and costly. Damage to both the titanium part and the machine tool are common, and little is known about what leads to this damage or how it can be controlled. This award supports fundamental research to investigate the mechanisms of deformation and wear during the process of machining titanium alloy parts. The very fine-scale structure of the alloys holds important keys to identify the root causes of tool wear, cutting behavior, and segmented chips in titanium machining, and understanding the fundamental relationships between this structure and processing will allow researchers to build the knowledge needed to to identify cutting tool design strategies and to optimize the alloy structure for better machinability, and predict the performance of a component. This new knowledge will have broad applicability in a number of manufacturing industries, including aerospace, automotive, and infrastructure. Additionally, strong educational benefits will result from this award, including diverse opportunities and experience for students in state-of-the-art research programs.This interdisciplinary team will bring researchers from Mechanical Engineering and Materials Science together to develop a fundamental understanding of how differences in the microstructure of titanium alloys affect machinability metrics. The microstructure of titanium alloys is quite complex, and most alloys (including the most common commercially used alloy, Ti-6Al-4V) have two distinct phases: an anisotropic hexagonal close-packed (HCP) phase, and a more isotropic body-centered cubic (BCC) phase. As a result of prior forming and heat treatment processes, many combinations of the two phases in various morphologies and textures are possible. This work will investigate how the microstructure prior to machining affects machinability metrics such as chip segmentation, tool wear, process dynamics, and the surface integrity of a finished product. The objective of this work is to identify and quantify the interplay between the titanium microstructure and these machinability metrics. A successful outcome will lead to science-based insights and rationale for choices of tools and cutting parameters that are tuned to the microstructure and composition of an alloy, and result in machined components with high structural integrity. This new knowledge will lead to the ability to describe and anticipate many observed phenomena such as micro-chipping on cutting tools, segmented chips and excessive tool wear at high cutting speeds. This will lead to rational approaches to reduce the overall processing cost by optimizing material specifications for machinability and product performance, as well as identifying improved ways to machine titanium alloys.