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Title: Experimental assessment of heat treatments on large forgings for nuclear applications by microstructure and mechanical property assessment at the correct length scale
Author: Kitchen, Jared
ISNI:       0000 0004 7431 1178
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2018
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The content of this thesis details the experimental verification and validation of new heat treatment simulation technology. The heat treatment simulator (HTS) takes the form of a large dilatometer, and generates volumes of material that accurately represent any simulated thermal program. What is novel and unique about the technology is that the volumes of material produced are large enough to allow both microstructure investigation and mechanical testing from individual specimens, and this functionality yields a method of experimentally assessing the effect of heat treatments on large forgings at the correct length scale. The experimental part of the thesis begins in Chapter 3 where initial investigations lead to an optimisation study. The study shows that large volumes of representative material are produced when simulating heat treatments using the HTS, but identifies the existence of systematic errors in the recorded results. This is investigated in Chapter 4, where a calibration procedure is developed that significantly reduces systematic error in the recorded data during testing. This work shows that the HTS can both simulate heat treatments accurately and can produce accurate data for analysis, and therefore its function is verified. Following verification, the HTS function is validated by two experimental studies. In Chapter 5, a new methodology of predicting property variation in large forgings is tested. A thermal profile of a large tubesheet forging undergoing heat treatment is simulated, and the results are compared to identical small-scale experiments. The results show that the HTS can be used to simulate complex thermal profiles accurately, but highlights the need for detailed material characterisations. In Chapter 6, the HTS is used to characterise the pressure vessel alloy SA508 Grade 3 Class 1 under continuous cooling conditions. The results are compared with small-scale experiments, giving validation, and allowing a continuous cooling transformation diagram to be plotted with mechanical properties, a functionality only possible using the HTS.
Supervisor: Wynne, Bradley Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available