Dr Pennington conducted his PhD research under the supervision of Professor Bradley Wynne and in conjunction with industrial partners NeoNickel Ltd. and Rolled Alloys Inc. The research focused on the thermo-mechanical processing of super duplex stainless steel, aiming to better understand microstructure development during forging and final quality heat treatment of components for extreme environment applications, such as offshore oil and gas subsea pipework systems, water desalination, and phosphoric acid production plants. This multi-scale, multi-faceted project aimed at achieving improved service life, more efficient manufacturing, and extending the performance envelope of this specific class of engineering material.
During his research, finite element analysis was employed to simulate temperature, stress, and strain distributions in components during forging and heat treatment. Experimental replication of the temperature and strain rate in industrial forging was investigated using the University’s Servotest Ltd. Thermo-Mechanical Compression machine. This formed the basis for developing a constitutive flow model to describe the plasticity of super duplex alloys over a range of thermo-mechanical processing conditions.
The electron backscattered detection technique, available through the facilities in the University’s Sorby Centre for Electron Microscopy, was utilized to analyze crystallographic textural developments resulting from thermo-mechanical processing. The research also involved establishing relationships between this crystallographic data and macro-scale mechanical properties, such as impact toughness and hardness, determined through Charpy testing and nanoindentation/Vickers hardness testing, respectively.