Potential Drop Monitoring of Creep Damage

管理蠕变是电力和其他工业中的一个主要问题，特别是随着设备老化，但目前还没有令人满意的方法来原位监测蠕变损伤的进展。提议者最近进行了一项可行性研究，该研究表明，可以通过监测平行于和垂直于加载方向的方向之间的电位降各向异性的演变来跟踪蠕变的进展。该技术可能是一种非常简单的监测蠕变的方法，但在该方法应用于工业之前必须解决几个基本问题。迄今为止，只有名义上均匀的铁素体钢已被测试，这些表现出显着的空洞蠕变过程中。其他重要的材料，如不锈钢，可以表现出较少的空洞，所以有必要更好地理解的电位降各向异性的演变机制，并调查其适用于奥氏体钢和镍基高温合金。此外，蠕变经常发生在焊缝，因此有必要确定母材和焊缝之间的固有电导率差异如何影响通过定向电位降测量测量的表观各向异性，以及这些不同微观结构中的不同热致微观结构演变是否导致虚假的表观各向异性变化，从而限制焊缝及其附近蠕变损伤的可检测性。虽然在某些应用中使用永久附接的探针进行监测是有吸引力的，但是在诸如涡轮机叶片的其他应用中，这是不可行的，因此有必要研究是否可以使用可展开的探针。该提案寻求资金来解决这些科学和工程问题，从而产生一种新的蠕变监测技术，特别有利于电力和相关行业。

Managing creep is a major issue in the power and other industries, particularly as plant ages, but there is currently no satisfactory method for in-situ monitoring the of progress of creep damage. The proposers have recently conducted a feasibility study that has shown that the progress of creep can be tracked by monitoring the evolution of potential drop anisotropy between directions parallel to and perpendicular to the loading direction. The technique is potentially a very simple method of monitoring creep, but several fundamental issues must be addressed before the method can be applied in industry. To date, only nominally homogeneous, ferritic steels have been tested, and these exhibit significant voiding during creep. Other important materials such as stainless steels can exhibit less voiding so it is necessary to understand better the mechanism of the evolution of the potential drop anisotropy and to investigate its applicability to austenitic steels and nickel base super alloys. In addition, creep often occurs at welds, so it is necessary to determine how the intrinsic conductivity difference between the base metal and the weld affects the apparent anisotropy measured by directional potential drop measurements, and also whether different thermally-induced microstructural evolution in these different microstructures leads to spurious apparent anisotropy changes, and hence limits the detectability of creep damage in welds and their neighbourhood. While monitoring using a permanently attached probe is attractive in some applications, in others such as turbine blades, it is not feasible so it is necessary to investigate whether a deployable probe can be used. This proposal seeks funds to address these scientific and engineering issues, and so to produce a new creep monitoring technique that will particularly benefit the power and related industries.