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Pinless Friction Stir Spot Welding Of Ti-6al-4v Alloy For Aerospace Application, Hyojin Park
Pinless Friction Stir Spot Welding Of Ti-6al-4v Alloy For Aerospace Application, Hyojin Park
Doctoral Dissertations
Friction Stir Spot Welding (FSSW) is a newly developed solid-state joining technique with considerable merits over conventional spot-welding techniques, such as relatively simple procedure and excellent welding properties. It has been successfully implemented for the joining of light-weight structural materials, such as Al- and Mg-based alloys, with superior weldability and reduction of the manufacturing costs and energy consumption. In addition, by removing the pin from the friction stir spot welding tool, the pinless FSSW (p-FSSW) has minimized the formation of welding defects such as keyhole and hooking, which resulted in further improvements in the mechanical properties of weldments. However, the …
Microstructure Control And Correlation To Creep Properties In Grade 91 Steel Weldment After Thermo-Mechanical Treatments And An Fe-30cr-3al Alloy Strengthened By Fe2nb Laves Phase, Benjamin Allen Shassere
Microstructure Control And Correlation To Creep Properties In Grade 91 Steel Weldment After Thermo-Mechanical Treatments And An Fe-30cr-3al Alloy Strengthened By Fe2nb Laves Phase, Benjamin Allen Shassere
Doctoral Dissertations
Type IV cracking in weldments of steel pipes after creep deformation is a concern in modern fossil-fueled power plants. Two possible methods for minimizing or eliminating Type IV cracking will be discussed. The first method alters the initial microstructure of typical Grade 91 steel base metal before welding, while the second provides baseline microstructure characteristics and creep performance of a new alloy that is strengthened by the intermetallic Fe2Nb Laves phase. The initial microstructure of the Grade 91 steel can be controlled by Thermo-Mechanical Treatments, which aids in precipitation of fine (5-10 nm) MX particles in austenite before transformation to …