scholarly journals Bending Behavior of a Wrought Magnesium Alloy Investigated by the In Situ Pinhole Neutron Diffraction Method

Crystals ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 348 ◽  
Author(s):  
Wei Wu ◽  
Alexandru Stoica ◽  
Dunji Yu ◽  
Matthew Frost ◽  
Harley Skorpenske ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Neutron Diffraction ◽  
Spatial Resolution ◽  
Diffraction Method ◽  
Middle Layer ◽  
Mapping Method ◽  
Step Size ◽  
Four Point Bending ◽  
Wrought Magnesium Alloy

The tensile twinning and detwinning behaviors of a wrought magnesium alloy have been investigated during in situ four-point bending using the state-of-the-art high spatial resolution pinhole neutron diffraction (PIND) method. The PIND method allowed us to resolve the tensile twinning/detwinning and lattice strain distributions across the bending sample during a loading-unloading sequence with a 0.5 mm step size. It was found that the extensive tensile twinning and detwinning occurred near the compression surface, while no tensile twinning behavior was observed in the middle layer and tension side of the bending sample. During the bending, the neutral plane shifted from the compression side to the tension side. Compared with the traditional neutron diffraction mapping method, the PIND method provides more detailed information inside the bending sample due to a higher spatial resolution.

Localization of Stresses in Polycrystalline Grains Measured by Neutron Diffraction and Predicted by Self-Consistent Model

2011 ◽  
Vol 681 ◽  
pp. 103-108
Author(s):  
Anita Gaj ◽  
Lea le Joncour ◽  
Andrzej Baczmanski ◽  
Sebastian Wroński ◽  
Benoit Panicaud ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Load Transfer ◽  
Diffraction Method ◽  
Lattice Strains ◽  
Consistent Model ◽  
Self Consistent ◽  
Main Component ◽  
Critical Resolved Shear Stress ◽  
Elastic Lattice

Time of flight neutron diffraction method was applied to measure elastic lattice strains in austenitic steel during "in situ" tensile test. Comparing experimental data with self-consistent model, the critical resolved shear stress and hardening parameters were determined for polycrystalline grains. The result allowed us to determine the main component of the stress localization tensor, relating the rate of grain stress with the applied macrostress rate. The evolution of concentration tensor in function of the applied macrostress was analyzed. Finally, the load transfer between grains during yielding of the sample was studied.

Measurement of Residual Stress Shakedown in Pressure/Tensile Armour Wires of Flexible Pipes by Neutron Diffraction

2015 ◽  
Author(s):  
Upul S. Fernando ◽  
Michelle Davidson ◽  
Christopher Simpson ◽  
Thilo Pirling ◽  
Kun Yan ◽  
...  
Keyword(s):  
Residual Stress ◽  
Neutron Diffraction ◽  
Metal Layer ◽  
Diffraction Method ◽  
Acceptance Test ◽  
Flexible Pipes ◽  
Before And After ◽  
Unbonded Flexible Pipes ◽  
Hoop Stresses

The manufacture of unbonded flexible pipes (flowlines and risers) involves wrapping steel wires to create pressure and tensile armour layers. The forming of armour wires from vendor supply conditions to a helix shape on the pipe involves significant plastic straining and the wires that are wrapped onto the pipe are not unloaded. Therefore the armour wires in flexible pipes are expected to contain significant residual stress (RS) as a result of the plastic straining and loading during manufacture and placement. This may lead to detrimental effects on the strength, durability and the service integrity of the pipe. It is postulated that the unfavorable RS introduced during pipe manufacture reduces due to stress shakedown during the factory acceptance test (FAT) where the pipe is subjected to a high internal pressure. This paper describes the first attempts to measure RS in the armour wires in unbonded flexible pipes. The key development is the use of a neutron diffraction method which allows the measurement of RS in-situ on the manufactured pipe through the whole wire sections. Pipe samples were prepared exposing the relevant metal layer and the measurements were performed on pipe samples taken before and after performing the pressurized FAT. The effect of the FAT on the shakedown of residual stress in pressure armour wires is discussed. As shown by the measurements, the elastic strains and stresses in the pressure armour wires are much larger in the hoop direction of the pipe (i.e. along the length of the wire) than radial or axial to the pipe. In pre-FAT pipe the hoop stresses are essentially tensile on the extrados and compressive on the intrados. The results have shown that the FAT reduces the hoop strains and stresses to approximately 1/3 of their as manufactured level.

In Situ Neutron Diffraction Study of Internal Stresses in 60% Mn-40% Cu Alloy Introduced by Ageing

2008 ◽  
Vol 137 ◽  
pp. 163-168
Author(s):  
S.G. Sheverev ◽  
G.V. Markova ◽  
V.V. Sumin
Keyword(s):  
Solid Solution ◽  
Neutron Diffraction ◽  
Diffraction Method ◽  
Neutron Diffraction Study ◽  
Internal Stresses ◽  
Ordered Structure ◽  
Cu Alloy ◽  
Decomposition Of Solid Solution ◽  
Neutron Diffraction Method

Spinodal decomposition of solid solution in the 60 at.% Mn - 40 at.% Cu alloy was observed at the temperatures of decomposition (380 – 420 °C) using the neutron diffraction method in situ. The contribution of residual stresses of third type introduced by further cooling of alloy and, correspondingly, martensitic tranformation is estimated. The relatively small value of stresses of third type introduced by martensitic transformation is revealed. Appearance of magnetic superstructural reflexes typical for antiferromagnetic ordered structure is noted.

scholarly journals Inclusion removal and grain refinement of magnesium alloy castings

2021 ◽  
Author(s):  
Abdallah Elsayed
Keyword(s):  
Magnesium Alloy ◽  
Neutron Diffraction ◽  
Grain Refinement ◽  
Magnesium Alloys ◽  
Ex Situ ◽  
Inclusion Removal ◽  
Carbon Inoculation ◽  
Aluminum Silicon Carbide ◽  
In Situ Neutron Diffraction

Magnesium alloys show promise to be materials for lightweighting of automotive and aerospace vehicles improving fuel efficiencies and vehicle performance. A majority of magnesium alloy components are produced using casting where susceptibility to forming inclusions and coarse grain sizes could result. Development of effective inclusion removal techniques and better understanding of grain refinement of magnesium alloys could help in improving their mechanical properties to advance them to more structurally demanding applications. This research aimed to develop an environmentally friendly alternative to the grain refinement and inclusion removal capabilities of carbon based hexachloroethane as it releases dioxins, chlorine gas and corrodes foundry equipment. A secondary aim was to pioneer in-situ neutron diffraction to examine the solidification of magnesium alloys. The research involved preparing tensile samples of AZ91E magnesium alloy using permanent mould casting. Inclusion removal was conducted by using filtration and argon gas bubbling. Castings grain refined using hexachloroethane (0.25, 0.50 and 0.75 wt.%) were compared against ex-situ aluminum-silicon carbide and in-situ aluminum-carbon based grain refiners combined with filtration and argon gas bubbling. Further, in-situ neutron diffraction was utilized for phase analysis and fraction solid determination of magnesium-zinc and magnesium-aluminum alloys. There was a significant improvement in yield strength, ultimate tensile strength and elongation with filtration plus argon bubbling, carbon inoculation or both filtration plus argon bubbling and carbon inoculation. The results indicated that the mechanism of the observed ~20% reduction in grain sizes with carbon inoculation (hexachloroethane, ex-situ aluminum-silicon carbide and in-situ aluminum-carbon) was explained through duplex nucleation of Mn-Al and Al-Mg-C-O (likely Al2MgC2) phases. Finally, in-situ neutron diffraction was used to follow the formation of Mg17Al12 eutectic phase in a magnesium-9 wt.% aluminum alloy. For the magnesium-zinc alloys, in-situ neutron diffraction enabled characterization of the effects of zirconium to the fraction solid growth of (1010), (0002) and (1011) α-Mg planes. The societal and environmental impact of this research is significant. There is a clear demonstration of alternatives to the universally used hexachloroethane grain refiner promoting harmful emissions. Improved mechanical properties resulting from new grain refinement and iv inclusion filtration are a major advancement in promoting weight reduction, improved castability and decreased environmental impact for automotive and aerospace industries.

scholarly journals Investigation of α-Ti plastic anisotropy under thermomechanical loadings: temperature influence on deformation mechanisms

2020 ◽  
Vol 321 ◽  
pp. 07004
Author(s):  
K. E. Agbovi ◽  
J. Fajoui ◽  
B. Girault ◽  
D. Gloaguen ◽  
S. Kabra ◽  
...  
Keyword(s):  
Neutron Diffraction ◽  
Bulk Material ◽  
Plastic Anisotropy ◽  
Diffraction Method ◽  
Tensile Tests ◽  
Deformation Mechanisms ◽  
Uniaxial Tensile ◽  
Lattice Strains ◽  
Deformation Modes

In situ neutron diffraction method has been used to investigate deformation mechanisms (slip and twinning deformation modes) during uniaxial tensile tests of extruded a-titanium alloy at room temperature, 100 and 300 °C. For this purpose, the prediction of an Elasto-Plastic Self-Consistent (EPSC) model was compared with the experimental data. Results show that there is a good agreement between the simulations and neutron diffraction measurements. The EPSC model enables realistic predictions of not only the elastic lattice strains developed in variously oriented grain families but also the macroscopic stress-strain response within the bulk material.

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