Investigation into Hot Isostatic Pressing of a 12% Chromium Martensitic Steel and optimisation of the bond to Nickel Based Alloy 625

该研究旨在展示和优化基于粉末的制造路线，以允许劳斯莱斯继续使用Jethete M153，该产品在商业上已经过时。罗尔斯·罗伊斯公司主要依靠这种合金的磁性性能来实现单一应用，但其有限的订单量使该合金面临着因失去锻造供应链而完全过时的严重风险。劳斯莱斯订单的数量和频率更好地与粉末供应路线保持一致。该博士将探讨粉末热等静压（HIP）制造路线是否可以成功地应用于Jethete M153，并将进一步了解组件的制造方法是否可以进行大修，以提高性能和结构完整性。罗尔斯·罗伊斯目前使用焊接将锻造的Jethete M153与镍基合金625连接起来，该合金已经通过粉末热等静压制造。如果这些材料可以通过热等静压结合进行连接，以提供等效或改进的使用性能，则组件转向完全基于粉末的制造路线可能会打开去除这种异种金属焊接的机会。如果成功，这将提高部件的结构完整性，减少制造和组装过程中的检查负担，并有可能为劳斯莱斯提供时间、成本和性能方面的好处。将根据焊接和焊后热处理淬火和回火的Jethete M153和固溶退火的HIP固结合金625的当前基线，对使用中性能进行基准测试。通过HIP连接Jethete M153和合金625将改变两种材料的使用条件，因为任何HIP后热处理都需要同时应用于两种材料。由于Jethete M153的磁性能是该组件的驱动要求，因此预计目前采用的淬火和回火也将应用于HIP固结产品，但需要优化该热处理，以确保Jethete M153的机械性能以及合金625的机械和环境性能可接受。热等静压将改变Jethete M153的微观结构和化学性质，这可能会影响其在使用条件下的磁性能。还将探索这种情况发生的程度（通过表征、DSC/示差扫描量热法和B-H回路测试），并研究HIP粉末原料，以了解可能改善后处理HIP Jethete M153性能的任何潜在优化。

This research aims to demonstrate and optimise a powder-based manufacturing route to allow Rolls-Royce continued use of Jethete M153 which is already commercially obsolete in its wrought form. Rolls-Royce rely on this alloy primarily for its magnetic performance for a single application but their limited order volumes puts the alloy at serious risk of total obsolescence through loss of a wrought supply chain. The volume and frequency of Rolls-Royce orders is better aligned to a powder supply route. This PhD will explore whether a powder hot isostatic pressing (HIP) manufacturing route can successfully be applied to Jethete M153 and will look further to understand if the component method of manufacture can be overhauled to improve the resulting performance and structural integrity. Rolls-Royce currently uses welding to join wrought Jethete M153 to nickel-based Alloy 625, already manufactured via powder HIP. Moving to a fully powder-based manufacturing route for the component potentially opens up an opportunity to remove this dissimilar metal weld if these materials can be joined via HIP bonding to give an equivalent or improved in-service performance. If successful, this will improve the component structural integrity and reduce the inspection burden during manufacture and assembly with the potential to provide time, cost and performance benefits to Rolls-Royce. In-service performance will be benchmarked against the current baseline of welded and post-weld heat treated quenched and tempered Jethete M153 and solution annealed HIP consolidated Alloy 625. Joining Jethete M153 and Alloy 625 via HIP will alter the in-service condition of the two materials as any post-HIP thermal treatment will need to be applied to both materials simultaneously. Since the magnetic performance of the Jethete M153 is the driving requirement for this component, it is expected that the currently employed quench and temper will also be applied to the HIP consolidated product, however optimisation of this thermal processing will be required to ensure acceptable mechanical performance of the Jethete M153 can be achieved as well as mechanical and environmental performance of the Alloy 625. HIP will alter the microstructure and chemistry of Jethete M153 which may influence its magnetic properties in the service condition. The extent to which this occurs will also be explored (via characterisation, DSC/dilatometry and B-H loop testing) and the HIP powder feedstock studied to understand any potential optimisations which may improve the performance of post-processed HIP Jethete M153.