Next Generation Materials Testing: Obtaining Anisotropic Plasticity Parameters using Profilometry-based Indentation Plastometry (PIP)

机械测试在几乎所有的工业部门都是常规的。它用于确保零部件的质量和安全性（通常由法规强制要求），揭示工艺和性能之间的重要关系，并支持新材料和新材料系统的开发。拉伸测试是机械测试的黄金标准，它测量材料的应力-应变性能。该测试涉及大型试样的机加工，并需要使用通用机械测试机。虽然被广泛使用，但拉伸测试可能是耗时和繁琐的，测试周转时间为几个小时，如果外包甚至几天，并且机械和资本设置成本很高。此外，测试会导致样品的破坏，并产生大量的废料。尽管显然需要改进测试方法，但一个规避风险的部门和过度依赖遵守测试标准阻碍了这一领域的进展。现在很明显，现行的测试程序已经过时，而且缺乏灵活性。Plastometrex（PLX）团队开发了一种用于金属材料的创新机械测试方法，称为PIP（或基于轮廓测量的压痕塑性测量）。PIP测量与拉伸测试相同的应力-应变特性，同时克服了其许多局限性。它使用简单，将测试周转时间从数小时缩短到仅三分钟，样品制备要求最低，并且可以测试真实的组件。它在执行上类似于普通硬度测试，但与硬度测试不同的是，测量整个残余轮廓形状。PIP方法包括三个主要任务：（1）使用我们的压痕塑性计（参见www.plastometrex.com）创建压痕，（2）使用集成触针轮廓仪测量残余轮廓形状，以及（3）使用我们的专有软件包SEMPID分析残余轮廓形状。PIP非常适合各向同性材料，即其属性在所有方向上都相同。然而，一些材料，例如增材制造（AM）金属，是各向异性的，即它们的性质根据取向而变化。该研究项目将扩展PIP的能力，包括各向异性材料，重点是AM金属，允许在不同方向上定量评估性能。AM可以彻底改变高价值制造业，允许快速原型制作，激进的设计创新，降低模具成本，缩短上市时间，降低生产成本，废物和排放。这项研究将使这些组件能够快速测试，并为制造商提供有关其部件性能的几乎实时的反馈。因此，它是AM技术的推动者，也是制造业和更广泛社会的潜在利益。这项研究将主要在Plastometrex有限公司进行，该公司是该研究员的主办机构，位于剑桥科学园。这项研究将涉及大量的实验室实验和建模工作。牛津大学是该项目的合作伙伴，他们对AM高温合金的高通量测试感兴趣，AM高温合金是一种在航空发动机和发电行业中无处不在的材料。制造技术中心（MTC）是该项目的合作者。他们将为研究提供材料，表征多孔结构数量的设备，以及他们对AM金属材料，加工和后处理的领先知识。国家物理实验室（NPL）将合作制定方法标准，并进行盲测拉伸试验，作为技术验证的一部分。

Mechanical testing is routinely used in almost all industrial sectors. It is used to ensure the quality and safety of components (often mandated by regulations), to reveal important relationships between processing and properties, and to support the development of new materials and novel material systems.The gold-standard for mechanical testing is the tensile test, which measures the stress-strain properties of materials. This test involves machining of a large test coupon and requires access to a universal mechanical test machine. Although widely used, the tensile test can be time-consuming and cumbersome, with testing turnaround times of hours or even several days if outsourced, and the machinery and capital set-up costs are high. In addition, the tests result in the destruction of the sample and they generate large amounts of wasted material. Despite the clear need for improved testing methods, a risk averse sector and an over-reliance on compliance with the testing standards has hampered progress within this area. It is now evident that current testing procedures are out-dated and inflexible. There is a strong motivation for developing faster, more efficient, more cost-effective, and less wasteful testing methods.The Plastometrex (PLX) team have developed an innovative mechanical testing method for metallic materials called PIP (or Profilometry-based Indentation Plastometry). PIP measures the same stress-strain properties as the tensile test while overcoming many of its limitations. It is simple to use, reduces testing turnaround times from hours to just three minutes, sample preparation requirements are minimal, and real components can be tested. It is similar in execution to the common hardness test, but unlike the hardness test the entire residual profile shape is measured. The PIP methodology involves three main tasks: (1) Creation of an indent using our Indentation Plastometer (see www.plastometrex.com), (2) Measurement of the residual profile shape using an integrated stylus profilometer, and (3) Analysis of the residual profile shape using our proprietary software package - SEMPID.PIP is well-suited for materials that are isotropic, i.e. its properties are the same in all directions. However some materials, such as additively manufactured (AM) metals, are anisotropic, i.e. their properties vary depending on the orientation. This research project will extend the capabilities of PIP to include anisotropic materials with a focus on AM metals, allowing quantitative assessment of the properties in different directions. AM could revolutionise the high value manufacturing sector, allowing rapid prototyping, radical design innovation, lower tooling costs, reduced time to market and lower production costs, waste and emissions. This research will allow these components to be rapidly tested, and provide manufacturers with almost real-time feedback on the properties of their parts. Therefore, it is an enabler for AM technology and the potential benefits for manufacturing and wider society that this brings. The research will mainly take place at Plastometrex Ltd, the host organisation of the fellow, based at the Cambridge Science Park. The research will involve a significant amount of laboratory experiments and modelling work. Oxford University are partners on the project, with their interest in high-throughput testing of AM superalloys, a family of materials that are ubiquitous in aero-engine and power-generation industries. The Manufacturing Technology Centre (MTC) are collaborators on the project. They will provide materials for the research, equipment for characterising the amount of structure of porosity, and their leading knowledge of materials, processing and post-processing for AM metals. The National Physical Laboratory (NPL) will collaborate on the development of a standard for the methodology and conduct tensile test experiments for blind testing as part of technology validation.