The friction stir processing (FSP) and welding of nickel aluminum bronze (NAB) is used for a vari... more The friction stir processing (FSP) and welding of nickel aluminum bronze (NAB) is used for a variety of naval applications, with the possibility of laser peening (LP) being used as a method for densification and mitigation of residual tensile stress. This paper investigates the beneficial effects of FSP on NAB passivity, and provides important benchmark data for future studies. Further enhancement of FSP NAB through application of LP will be discussed in subsequent papers, using the data presented here as a basis of comparison. This work shows that FSP has a beneficial effect on both the microstructure of this alloy, as well as on the integrity of the passive film formed in chloride electrolytes, including natural seawater. In addition to using a variety of characterization techniques to determine the effects of friction stir processing on microstructure, including scanning electron microscopy (SEM) with focused ion beam milling, we have used cyclic polarization (CP) and electrochem...
Microstructural evolution via static continuous recrystallization during thermomechanical process... more Microstructural evolution via static continuous recrystallization during thermomechanical processing of an Al-Mg-Zr alloy is addressed. Mechanical property data demonstrated that as-rolled material was capable of superplastic response without further treatment. Further, superplastic ductility at 300 C was enhanced by a factor of five by increasing the reheating time between rolling passes during processing also at 300 C. This enhanced ductility was associated with a Cu-texture and a microstructure consisting of predominantly high-angle boundaries. Processing to minimize recovery resulted in a strong Brass-texture component, a predominantly low-angle boundary microstructure and poorer ductility.
Thermomechanical processing to enable superplasticity in AA5083 materials includes cold working f... more Thermomechanical processing to enable superplasticity in AA5083 materials includes cold working followed by heating prior to hot blow forming. Upon heating for forming at 450°C, a B-type ({110}) rolling texture is replaced by a near-random texture with a weak superimposed cube orientation parallel to the sheet normal. The presence of refined grains 7 – 8μm in size reflects the predominance of particle-stimulated nucleation of recrystallization prior to forming. The subsequent evolution of microstructure, texture and cavitation behaviour during biaxial deformation in the solute drag creep (SDC) and grain boundary sliding (GBS) regimes will be presented.
The present conference on emerging applications of superplastically formable materials discusses ... more The present conference on emerging applications of superplastically formable materials discusses the superplastic deformation mechanisms of aluminum alloys, microstructural evolution in a P/M 7xxx Al alloy, fine-grained superplasticity at 300 C in a wrought Al-Mg alloy, and the extended ductility of Al and alpha-Fe alloys through dynamic recovery mechanisms. Also discussed are models for superplastic forming under axisymmetric and plane-strain conditions, cavitation failure in superplastic alloys, the effects of void formation on superplastic 7475 Al alloy mechanical properties, superplasticity in SiC whisker-reinforced Al alloys and mechanically-alloyed Al aerospace alloys, the effect of microstructure on Al-Li-X alloys' superplastic behavior, and hollow Ti-alloy turbofan blades' superplastic forming.
The friction stir processing (FSP) and welding of nickel aluminum bronze (NAB) is used for a vari... more The friction stir processing (FSP) and welding of nickel aluminum bronze (NAB) is used for a variety of naval applications, with the possibility of laser peening (LP) being used as a method for densification and mitigation of residual tensile stress. This paper investigates the beneficial effects of FSP on NAB passivity, and provides important benchmark data for future studies. Further enhancement of FSP NAB through application of LP will be discussed in subsequent papers, using the data presented here as a basis of comparison. This work shows that FSP has a beneficial effect on both the microstructure of this alloy, as well as on the integrity of the passive film formed in chloride electrolytes, including natural seawater. In addition to using a variety of characterization techniques to determine the effects of friction stir processing on microstructure, including scanning electron microscopy (SEM) with focused ion beam milling, we have used cyclic polarization (CP) and electrochem...
Microstructural evolution via static continuous recrystallization during thermomechanical process... more Microstructural evolution via static continuous recrystallization during thermomechanical processing of an Al-Mg-Zr alloy is addressed. Mechanical property data demonstrated that as-rolled material was capable of superplastic response without further treatment. Further, superplastic ductility at 300 C was enhanced by a factor of five by increasing the reheating time between rolling passes during processing also at 300 C. This enhanced ductility was associated with a Cu-texture and a microstructure consisting of predominantly high-angle boundaries. Processing to minimize recovery resulted in a strong Brass-texture component, a predominantly low-angle boundary microstructure and poorer ductility.
Thermomechanical processing to enable superplasticity in AA5083 materials includes cold working f... more Thermomechanical processing to enable superplasticity in AA5083 materials includes cold working followed by heating prior to hot blow forming. Upon heating for forming at 450°C, a B-type ({110}) rolling texture is replaced by a near-random texture with a weak superimposed cube orientation parallel to the sheet normal. The presence of refined grains 7 – 8μm in size reflects the predominance of particle-stimulated nucleation of recrystallization prior to forming. The subsequent evolution of microstructure, texture and cavitation behaviour during biaxial deformation in the solute drag creep (SDC) and grain boundary sliding (GBS) regimes will be presented.
The present conference on emerging applications of superplastically formable materials discusses ... more The present conference on emerging applications of superplastically formable materials discusses the superplastic deformation mechanisms of aluminum alloys, microstructural evolution in a P/M 7xxx Al alloy, fine-grained superplasticity at 300 C in a wrought Al-Mg alloy, and the extended ductility of Al and alpha-Fe alloys through dynamic recovery mechanisms. Also discussed are models for superplastic forming under axisymmetric and plane-strain conditions, cavitation failure in superplastic alloys, the effects of void formation on superplastic 7475 Al alloy mechanical properties, superplasticity in SiC whisker-reinforced Al alloys and mechanically-alloyed Al aerospace alloys, the effect of microstructure on Al-Li-X alloys' superplastic behavior, and hollow Ti-alloy turbofan blades' superplastic forming.
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Papers by T. McNelley