scholarly journals Grain Size-Related Strengthening and Softening of a Precompressed and Heat-Treated Mg–Zn–Ca Alloy

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 351 ◽  
Author(s):  
Patrik Dobroň ◽  
Daria Drozdenko ◽  
Klaudia Horváth Fekete ◽  
Juraj Olejňák ◽  
Jan Bohlen
Keyword(s):  
Grain Size ◽  
Thermal Treatment ◽  
Electron Backscatter Diffraction ◽  
Deformation Behaviour ◽  
Strengthening Effect ◽  
Average Grain Size ◽  
Ebsd Technique ◽  
Size Interval ◽  
Evolution Of Microstructure ◽  
The Impact

The impact of precompression, thermal treatment and its combination on the deformation behaviour of an extruded Mg–Zn–Ca (ZX10) alloy was studied with respect to a varied average grain size. The Hall–Petch plot was used to highlight the impact in a wide grain size interval. The initial texture of the wrought alloy was characterized by X-ray diffraction. Moreover, the evolution of microstructure and texture was provided by the electron backscatter diffraction (EBSD) technique. The obtained results indicate the strong contribution of deformation-thermal treatment on the resulting deformation behaviour. Particularly, after precompression and heat treatment, higher strengthening effect was observed in the reversed tensile loaded compared to compressed samples without any change in the Hall–Petch slope throughout the grain size interval. Unlike this strengthening effect, a reversed tension–compression yield asymmetry with higher strength values in compression has been obtained.

scholarly journals Corrosion Behaviour of Multiaxial Compressed AlMgSi alloy

2021 ◽  
Vol 71 (03) ◽  
pp. 359-364
Author(s):  
Abir Roy ◽  
Abhishek Kumar
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Test ◽  
Electron Backscatter Diffraction ◽  
Corrosion Behaviour ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Average Grain Size ◽  
The Impact ◽  
Almgsi Alloy

In the present study, AlMgSi alloy was processed through multi-axial compression (MAC) to produce ultrafine-grained microstructure at room temperature. The AlMgSi alloys are widely used in automobile industries for making cylinder heads and brake disks etc. MAC was performed up to three cycles and showed improvement in mechanical properties. The impact of different strain levels upon microstructure changes is investigated using electron backscatter diffraction (EBSD). The average grain size reduced from an initial average grain size of ~ 124 to ~ 3 μm after completion of three cycles of MAC processing. Samples were tested for mechanical properties using uniaxial tensile test, hardness measurements, and corrosion. Tensile test results show a considerable increase in yield strength from ~90 MPa to ~249 MPa after 3 cycles of MAC. The average hardness value increased from 52 VHN to 90 VHN after 3 cycles of MAC. The corrosion resistance of MAC processed samples was found to decrease in comparison to solution-treated samples.

scholarly journals ODS EUROFER Steel Strengthened by Y-(Ce, Hf, La, Sc, and Zr) Complex Oxides

Metals ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 1148 ◽  
Author(s):  
Roman Husák ◽  
Hynek Hadraba ◽  
Zdeněk Chlup ◽  
Milan Heczko ◽  
Tomáš Kruml ◽  
...  
Keyword(s):  
Grain Size ◽  
Yield Strength ◽  
Complex Oxides ◽  
Oxide Dispersion Strengthened ◽  
Interparticle Spacing ◽  
Oxide Dispersion ◽  
Strengthening Effect ◽  
Dispersion Strengthening ◽  
Doping Element ◽  
Average Grain Size

Oxide dispersion-strengthened (ODS) materials contain homogeneous dispersions of temperature-stable nano-oxides serving as obstacles for dislocations and further pinning of grain boundaries. The strategy for dispersion strengthening based on complex oxides (Y-Hf, -Zr, -Ce, -La) was developed in order to refine oxide dispersion to enhance the dispersion strengthening effect. In this work, the strengthening of EUROFER steel by complex oxides based on Y and elements of the IIIB group (lanthanum, scandium) and IVB group (cerium, hafnium, zirconium) was explored. Interparticle spacing as a dispersoid characteristic appeared to be an important factor in controlling the dispersion strengthening contribution to the yield strength of ODS EUROFER steels. The dispersoid size and average grain size of ODS EUROFER steel were altered in the ranges of 5–13 nm and 0.6–1.7 µm, respectively. Using this strategy, the yield strength of the prepared alloys varied between 550 MPa and 950 MPa depending on the doping element.

scholarly journals A Physical-Based Plane Stress Constitutive Model for High Strength AA7075 under Hot Forming Conditions

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 314
Author(s):  
Fulong Chen ◽  
Haitao Qu ◽  
Wei Wu ◽  
Jing-Hua Zheng ◽  
Shuguang Qu ◽  
...  
Keyword(s):  
Grain Size ◽  
Aluminum Alloy ◽  
Plane Stress ◽  
Metal Forming ◽  
Electron Backscatter Diffraction ◽  
High Strength ◽  
Material Model ◽  
Hot Forming ◽  
Industrial Processing ◽  
Average Grain Size

Physicallybased constitutive equations are increasingly used for finite element simulations of metal forming processes due to the robust capability of modelling of underlying microstructure evolutions. However, one of thelimitations of current models is the lack of practical validation using real microstructure data due to the difficulties in achieving statistically meaningful data at a sufficiently large microstructure scale. Particularly, dislocation density and grain size governing the hardening in sheet deformation are of vital importance and need to be precisely quantified. In this paper, a set of dislocation mechanics-based plane stress material model is constructed for hot forming aluminum alloy. This material model is applied to high strength 7075 aluminum alloy for the prediction of the flow behaviorsconditioned at 300–400 °C with various strain rates. Additionally, an electron backscatter diffraction (EBSD) technique was applied to examine the average grain size and geometrical necessary dislocation (GND) density evolutions, enabling both macro- and micro- characteristics to be successfully predicted. In addition, to simulate the experienced plane stress states in sheet metal forming, the calibrated model is further extended to a plane stress stateto accuratelypredict the forming limits under hot conditions.The comprehensively calibrated material model could be used for guidinga better selection of industrial processing parameters and designing process windows, taking into account both the formed shape as well as post formed microstructure and, hence, properties.

scholarly journals Application of Electron Backscatter Diffraction (EBSD) for Crystallographic Characterization of Aluminum-Doped Zinc Oxide Sputtered Films

2013 ◽  
Vol 19 (S4) ◽  
pp. 103-104
Author(s):  
C.B. Garcia ◽  
E. Ariza ◽  
C.J. Tavares
Keyword(s):  
Electron Microscopy ◽  
Grain Size ◽  
Zinc Oxide ◽  
Electron Backscatter Diffraction ◽  
Wide Range ◽  
Electron Backscatter ◽  
Aluminum Doped Zinc Oxide ◽  
Ebsd Technique ◽  
Backscatter Diffraction

Zinc Oxide is a wide band-gap compound semiconductor that has been used in optoelectronic and photovoltaic applications due to its good electrical and optical properties. Aluminium has been an efficient n-type dopant for ZnO to produce low resistivity films and high transparency to visible light. In addition, the improvement of these properties also depends on the morphology, crystalline structure and deposition parameters. In this work, ZnO:Al films were produced by d.c. pulsed magnetron sputtering deposition from a ZnO ceramic target (2.0 wt% Al2O3) on glass substrates, at a temperature of 250 ºC.The crystallographic orientation of aluminum doped zinc oxide (ZnO:Al) thin films has been studied by Electron Backscatter Diffraction (EBSD) technique. EBSD coupled with Scanning Electron Microscopy (SEM) is a powerful tool for the microstructural and crystallographic characterization of a wide range of materials.The investigation by EBSD technique of such films presents some challenges since this analysis requires a flat and smooth surface. This is a necessary condition to avoid any shadow effects during the experiments performed with high tilting conditions (70º). This is also essential to ensure a good control of the three dimensional projection of the crystalline axes on the geometrical references related to the sample.Crystalline texture is described by the inverse pole figure (IPF) maps (Figure 1). Through EBSD analysis it was observed that the external surface of the film presents a strong texture on the basal plane orientation (grains highlighted in red colour). Furthermore it was possible to verify that the grain size strongly depends on the deposition time (Figure 1 (a) and (b)). The electrical and optical film properties improve with increasing of the grain size, which can be mainly, attributed to the decrease in scattering grain boundaries which leads to an increasing in carrier mobility (Figure 2).The authors kindly acknowledge the financial support from the Portuguese Foundation for Science and Technology (FCT) scientific program for the National Network of Electron Microscopy (RNME) EDE/1511/RME/2005.

Effect of Annealing Time on the Microstructure and Texture of Interstitial Free Steel

2012 ◽  
Vol 535-537 ◽  
pp. 593-596
Author(s):  
Zhi Fen Wang ◽  
Rong Dong Han ◽  
Shun Bing Zhou ◽  
Zhong Hai Yao ◽  
Li Xin Wu
Keyword(s):  
Grain Size ◽  
Annealing Time ◽  
Electron Backscatter Diffraction ◽  
Recrystallization Process ◽  
Interstitial Free ◽  
X Ray Diffraction ◽  
Steel Sheets ◽  
Grain Boundary Character ◽  
Average Grain Size ◽  
Backscatter Diffraction

Effect of annealing time on the microstructure and texture of IF steel sheets was investigated. Average grain size, grain boundary character and recrystallization texture were measured by X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) in order to clarify the effect of annealing time on microstructure of recrystallization process. The average grain size increased with increasing annealing time. With rising annealing time, the number of low angle boundary (0～15o) decreased due to the mergence of grain with sub-boundary. The //ND (-fiber) pole intensity had a highest value annealed at 60s. The annealing time played an important role in recrystallization process which affected the mechanical properties and microstructure of IF steels.

scholarly journals Features of the formation of structure and mechanical properties in rolled products of various thicknesses from low-carbon microalloyed steel produced by casting and rolling complex

2021 ◽  
Vol 64 (9) ◽  
pp. 669-678
Author(s):  
V. V. Naumenko ◽  
K. S. Smetanin ◽  
А. V. Muntin ◽  
O. А. Baranova ◽  
S. V. Kovtunov
Keyword(s):  
Grain Size ◽  
Stress Concentrator ◽  
Microalloyed Steel ◽  
Rolling Direction ◽  
Large Angle ◽  
Low Carbon ◽  
Rolled Metal ◽  
Average Grain Size ◽  
Carbon Microalloyed ◽  
The Impact

The article considers results of the study of microstructure parameters effect on the impact strength in temperature range from 0 to –80  °C in 20  °C increments of Charpy samples with a sharp stress concentrator and Mesnager test pieces with a circular stress concentrator from rolled coils of low-carbon microalloyed steel with various thicknesses. The used roll products were produced in conditions of JSC “Vyksa Metallurgical Plant”. The tests were performed using optical and scanning electron microscopy. It is shown that with the same chemical composition and thermomechanical treatment modes, the metal of smaller thickness (6, 8 mm) is characterized by higher strength properties (on average, by 10 MPa for temporary resistance, by 30 MPa for yield strength) and a margin for viscous properties at negative temperatures at close values of grain score and average grain size corresponding to 10 – 11 numbers according to the State standard GOST 5639. The metal with a thickness of 12 mm has the lowest level of cold resistance, and the temperature of brittle transition is minus 50 °C. Structure of rolled products of various thicknesses has a variation in grain size. Rolled metal of smaller thicknesses have a smaller grains corresponding to number 14, rolled metal of larger thicknesses has a larger grains corresponding to number 8. By conducting electron microscopic studies using the backscattered electron method, it was found that a greater number of large-angle boundaries, which are barriers for brittle cracks propagation, are observed in the 6, 8 mm thick rolled products. The constructed orientation maps of the microstructure showed the presence of pronounced deformation texture corresponding to the orientations <110>||RD (rolling direction) and (<113>...<112>)||RD for rolled products with a thickness of 6 mm.

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