The role of grain size in static and cyclic deformation behaviour of a laser reversion annealed metastable austenitic steel

Different grain sizes were created in a metastable 17Cr‐7Mn‐7Ni steel by martensite‐to‐austenite reversion at different temperatures using a laser beam. Two fully reverted material states obtained at 990°C and 780°C exhibited average grain sizes of 7.7 and 2.7 μm, respectively. The third microstructure (610°C) consisted of grains at different stages of recrystallization and deformed austenite. A hot‐pressed, coarse‐grained counterpart was studied for reference. The yield and tensile strengths increased with refined grain size, maintaining reasonable elongation except for the heterogeneous microstructure. Total strain‐controlled fatigue tests revealed increasing initial stress amplitudes but decreasing cyclic hardening and fatigue‐induced α′‐martensite formation with decreasing grain size. Fatigue life was slightly improved for the 2.7‐μm grain size. Contrary, the heterogeneous microstructure yielded an inferior lifetime, especially at high strain amplitudes. Examinations of the cyclically deformed microstructure showed that the characteristic deformation band structure was less pronounced in refined grains.     

Oat beta-glucan and xylan hydrolysates as selective substrates for Bifidobacterium and Lactobacillus strains

The opposing asymmetry of the frontoparietal brain regions has been referred to as 'torque' and may be used as an index of speed of neurodevelopment. It has been recently suggested that torque is minimized in male schizophrenia, reflecting anomalous neurodevelopment. This study examined volumetric and linear torque in a group of 20 schizophrenia patients and 20 healthy individuals; all were right-handed and under the age of 46 years. None of the main or interaction effects on torque were statistically significant, although the sex difference in torque among schizophrenia patients (male larger than female) was more than seven times that in healthy subjects. Torque was significantly associated with years of education and age of illness onset (schizophrenia). These findings support the hypothesis that slowed neurodevelopment may be associated with male schizophrenia and may contribute to earlier age of onset and fewer years of education.     

High-Speed Erichsen Testing of Grain-Refined 301LN Austenitic Stainless Steel Processed by Double-Reversion Annealing

Metallurgical and Materials Transactions A - Austenitic Cr–Ni stainless-type 301LN steel was subjected to a double-reversion annealing (DRA) treatment to develop bulk grain-refined...     

Correlation Between Potentiodynamic Polarization Behaviors of Transient Liquid Phase Bonded 2205 Duplex Stainless Steel and the Bonding Constituents

In order to precisely evaluate the contribution of each bonding constituent to the pitting corrosion resistance of transient liquid phase (TLP) bonded 2205 duplex stainless steel (DSS), we have undertaken potentiodynamic polarization (PDP) and microstructural analytic measurements all across the TLP bonded area. The PDP results show that the pitting corrosion resistance of TLP bonded specimens is significantly affected by the presence of certain bonding constituents across the TLP bonded area. Electron microscopy analysis indicates that the formation of complex (Fe,Ni,Cr,Mo)₃P phosphide in the bonding zone (BZ) before the completion of isothermal solidification (IS) as well as the formation of P-rich sigma phase in the diffusion-affected zone (DAZ) following the completion of the IS provides the most preferential sites for the occurrence of pitting corrosion. The PDP results also confirm that the pitting potentials (E_pit) of the TLP bonded specimen before and after IS completion are, respectively, closer to the E_pit of the BZ and the E_pit of the DAZ rather than to those of other TLP BZs.

     

The Outstanding Contribution of Basal Slip in Substructure Development during Friction Stir Processing of Magnesium Alloys

This research reveals the critical role of basal slip in the substructure development during friction stir processing of a magnesium alloy. In this respect, the intragranular lattice rotation axes are considered to identify the activity of different slip systems. The applied shear strain during the procedure is stored in the matrix through slip-induced rotations at the grain level. The rotations around distinct Taylor axes produce “slip domains” separated by necessary boundaries from the parent grains, significantly contributing in grain refinement. The basal slip is easily activated in grains holding different stored energy; however, the nonbasal slip has a higher dependency on the amount of local applied strain. Determining the contribution of different slip systems in strain accommodation reveals that the basal slip imposes the highest fraction of low-angle boundaries into the microstructure leading to the development of the ultimate grain boundary structure.