Microstructure Evolution and Hardness Distribution in Al Wires Subjected to Simultaneous Tension-Torsion Deformation

2015 ◽  
Vol 651-653 ◽  
pp. 771-776
Author(s):  
Mojtaba Pourbashiri ◽  
Mohammad Sedighi ◽  
Cecilia Poletti ◽  
Christof Sommitsch
Keyword(s):  
Grain Refinement ◽  
Cross Sections ◽  
Microstructure Evolution ◽  
Equivalent Plastic Strain ◽  
Hardness Measurement ◽  
Equivalent Strain ◽  
Grain Structure ◽  
Hardness Distribution ◽  
Simultaneous Torsion ◽  
The Wire

Commercially pure Al wires are drawn through equal channel angular dies with simultaneous torsion. The wires are deformed up to an equivalent strain of 1 to 4 at room temperature after several passes. The microstructure evolution of the wires is investigated using optical microscopy at both longitudinal and transverse cross sections. A grain refinement to a mean grain size of 10 to 15 μm is achieved by using this process. Finer grain structure is observed at the edge area of the wires due to the non-uniform strain distribution. The micro-hardness measurement indicates that the hardness distribution is inhomogeneous and increasing from a minimum value at the wire centre to a maximum value at the wire edge. Finite element (FE) results show that by using a channel angel of 160° and an initial wire diameter of 4 mm during one pass, an equivalent plastic strain of about 0.4 at the wire centre and 0.9 at the wire edge can be achieved. The most important advantage of this process is the ability to impose continuous severe plastic deformation to wires. This new hybrid process could be used as an industrial method for continuous grain refinement of wires.

Microstructure Evolution during High Pressure Torsion of AZ80 Magnesium Alloy

2008 ◽  
Vol 584-586 ◽  
pp. 300-305 ◽  
Author(s):  
Dogan Arpacay ◽  
Sang Bong Yi ◽  
Miloš Janeček ◽  
Adem Bakkaloglu ◽  
Lothar Wagner
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Pressure ◽  
Magnesium Alloy ◽  
Grain Refinement ◽  
Microstructure Evolution ◽  
Significant Variation ◽  
High Pressure Torsion ◽  
Grain Structure ◽  
Az80 Magnesium Alloy

The microstructure evolution during high pressure torsion and its influence on the mechanical properties of AZ80 magnesium alloy is presented in this study. Significant grain refinement was observed after high pressure torsion, while the homogeneity of the grain structure increases with the number of revolutions. Grain size decreases to about 50 nm after 15 revolutions. The microhardness profiles measured at through-thickness and through-width directions show no significant variation at different positions of the sample. Moreover, the negligible effect of the revolution number on the microhardness value was observed.

Cross Section Analysis of Cu Filled TSVs Based on High Throughput Plasma-FIB Milling

2012 ◽  
Author(s):  
Frank Altmann ◽  
Jens Beyersdorfer ◽  
Jan Schischka ◽  
Michael Krause ◽  
German Franz ◽  
...  
Keyword(s):  
High Resolution ◽  
Cross Section ◽  
High Throughput ◽  
Cross Sections ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Electron Backscatter ◽  
Section Surface ◽  
Backscatter Diffraction ◽  
Section Analysis

Abstract In this paper the new Vion™ Plasma-FIB system, developed by FEI, is evaluated for cross sectioning of Cu filled Through Silicon Via (TSV) interconnects. The aim of the study presented in this paper is to evaluate and optimise different Plasma-FIB (P-FIB) milling strategies in terms of performance and cross section surface quality. The sufficient preservation of microstructures within cross sections is crucial for subsequent Electron Backscatter Diffraction (EBSD) grain structure analyses and a high resolution interface characterisation by TEM.

scholarly journals Microstructural Evolutions of 2N Grade Pure Al and 4N Grade High-Purity Al during Friction Stir Welding

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3606
Author(s):  
Tomoya Nagira ◽  
Xiaochao Liu ◽  
Kohasaku Ushioda ◽  
Hidetoshi Fujii
Keyword(s):  
Friction Stir Welding ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
High Purity ◽  
Cube Texture ◽  
Grain Structure ◽  
Welding Temperature ◽  
Friction Stir ◽  
Continuous Dynamic Recrystallization ◽  
Dislocation Annihilation

The grain refinement mechanisms along the material flow path in pure and high-purity Al were examined, using the marker insert and tool stop action methods, during the rapid cooling friction stir welding using liquid CO2. In pure Al subjected to a low welding temperature of 0.56Tm (Tm: melting point), the resultant microstructure consisted of a mixture of equiaxed and elongated grains, including the subgrains. Discontinuous dynamic recrystallization (DDRX), continuous dynamic recrystallization (CDRX), and geometric dynamic recrystallization are the potential mechanisms of grain refinement. Increasing the welding temperature and Al purity encouraged dynamic recovery, including dislocation annihilation and rearrangement into subgrains, leading to the acceleration of CDRX and inhibition of DDRX. Both C- and B/-type shear textures were developed in microstructures consisting of equiaxed and elongated grains. In addition, DDRX via high-angle boundary bulging resulted in the development of the 45° rotated cube texture. The B/ shear texture was strengthened for the fine microstructure, where equiaxed recrystallized grains were fully developed through CDRX. In these cases, the texture is closely related to grain structure development.

scholarly journals Producing High Wettable Surface on Pure Titanium Sheets by Shot Peening for Bone Implant Applications

2021 ◽  
Vol 12 (5) ◽  
pp. 5745-5752
Keyword(s):  
Grain Refinement ◽  
Shot Peening ◽  
Pure Titanium ◽  
Contact Angles ◽  
Grain Structure ◽  
Microstructure Modification ◽  
Fine Grain ◽  
Angle Measurements ◽  
Peak Broadening ◽  
Contact Angle Measurements

Pure titanium (Ti) sheets were subjected to shot peening to achieve grain refinement at the surface. Microstructural studies revealed significant grain refinement at the surface of the Ti sheet after shot peening. The affected thickness of the grain refined region was measured as 150 µm at the cross-section. Due to the fine grain structure, higher hardness was measured for the processed surface. X-ray diffraction studies of the processed sample showed peak broadening for processed Ti due to shot peening. Wettability studies conducted by contact angle measurements clearly showed increased hydrophilicity for the processed Ti as reflected in the lower contact angles. Increased surface energy was calculated for the shot-peened Ti, which can be attributed to the role of the increased fraction of grain boundaries due to microstructure modification. The results demonstrate the potential of the shot peening process to improve the surface wettability and further directly enhance the bioactivity of the Ti implant.

Applicability of Solid Lubricant Coatings in Cold Rod Extrusion of Stainless Steels

2020 ◽  
Vol 404 ◽  
pp. 95-100
Author(s):  
Andreas Jobst ◽  
Marion Merklein
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Work Hardening ◽  
Room Temperature ◽  
Fatigue Behavior ◽  
Equivalent Plastic Strain ◽  
Grain Structure ◽  
Cold Extrusion ◽  
Operating Characteristics ◽  
Lubricant Coating

Cold extrusion is an established technology for the production of dimensionally accurate components in large series. Due to the high material and energy efficiency, a resource-saving manufacturing of high-performance parts is possible. Forming at room temperature leads to an advantageous grain structure and work hardening of the material, resulting in components with favorable operating characteristics. Nevertheless, a challenge is the generation of residual stresses during forming, which are influencing the fatigue behavior. The modification of the tribological conditions is one method for influencing the parts’ residual stress state. However, the high strength and work hardening of the materials formed at room temperature leads to high tribological loads between billet and die. These challenges are intensified by the increasing use of stainless steels due to growing demands for corrosion resistant components. The aim followed within this paper is therefore to investigate the applicability of typical lubricant coatings in the forward rod extrusion of stainless steels. For this purpose, the ferritic stainless steel X6Cr17 (DIN 1.4016) and the ferritic-austenitic stainless steel X2CrNiMoN22-5-3 (DIN 1.4462) are extruded with an equivalent plastic strain of ε̅ ≈ 1. The research is performed with a molybdenum disulfide (MoS2), a soap and a polymer-based lubricant coating. For reproducing different contact conditions, the die geometry is varied with die opening angles of 60°, 90° and 120°. The suitability of the lubricants is evaluated using the integrity of the lubricant coating after forming. From the correlations between process forces, temperatures and surface integrity, recommendations for the application of the researched lubricants are derived.

Grain Structure and Surface Roughness of Four Commercial NiTi Orthodontic Archwires

2017 ◽  
Vol 266 ◽  
pp. 257-263
Author(s):  
Wassana Wichai ◽  
Rutchadakorn Isarapatanapong ◽  
Niwat Anuwongnukroh ◽  
Surachai Dechkunakorn
Keyword(s):  
Surface Roughness ◽  
Grain Size ◽  
Optical Microscope ◽  
Grain Structure ◽  
Wire Surface ◽  
Average Grain Size ◽  
Electron Mode ◽  
The Mean ◽  
The Wire ◽  
Orthodontic Archwires

This study investigated four commercially available NiTi orthodontic archwires from different manufactures for their grain structure and surface roughness.Four commercially available pre-formed NiTi orthodontic archwire (Ormco, Sentalloy, Highland and NIC) with diameter 0.016 x 0.022 inch2 were tested. The wire samples were polished and etched to evaluate the morphology and structure of wire surface. Each NiTi archwire was investigated under a reflected light microscope of an Optical Microscope to analyze its grain structure and size, in longitudinal surfaces. The surfaces of wire were qualitatively examined in the secondary electron mode at common magnification (500X). The surface roughness was also evaluated by a surface roughness tester. The descriptive statistic was evaluated the mean and standard deviation of surface roughness and Medcale T-Test was to test the mean difference of the surface roughness in each brands. This study showed an average grain size of 2-8 μm for each NiTi archwire. The wire surface of Ormco and Highland showed straiations along the longitudinal axes, however Sentalloy and NIC showed small pores on the wire surface. The surface roughness was 0.09 μm for Highland, 0.25 μm for Sentalloy, 0.28 μm for Ormco and 0.46 μm for NIC archwire. The Highland was smoothest and NIC was the roughest. There were in significant (p < 0.05) difference of surface roughness of each brands. The results showed that the four manufactures NiTi archwires were different in grain size, wire surface and surface roughness. During clinical application, these archwires may exhibit different mechanical properties, such as strength, hardness, ductity, and friction because of their microstructure.

Mesoscale Simulations of Microstructure Evolution in a Temperature Gradient

2010 ◽  
Vol 1264 ◽  
Author(s):  
Bala Radhakrishnan ◽  
Gorti Sarma
Keyword(s):  
Temperature Gradient ◽  
Grain Boundary ◽  
Pore Size ◽  
Microstructure Evolution ◽  
Volume Diffusion ◽  
Grain Structure ◽  
Migration Direction ◽  
Boundary Force ◽  
Mesoscale Simulations ◽  
Model Approach

AbstractThe evolution of pore and grain structure in a nuclear fuel environment is strongly influenced by the local temperature, and the temperature gradient. The evolution of pore and grain structure in an externally imposed temperature gradient is simulated for a hypothetical material using a Potts model approach that allows for porosity migration by mechanisms similar to surface, grain boundary and volume diffusion, as well as the interaction of migrating pores with stationary grain boundaries. First, the migration of a single pore in a single crystal in the presence of the temperature gradient is simulated. Next, the interaction of a pore moving in a temperature gradient with a grain boundary that is perpendicular to the pore migration direction is simulated in order to capture the force exerted by the pore on the grain boundary. The simulations reproduce the expected variation of pore velocity with pore size as well as the variation of the grain boundary force with pore size.

Shear Pressing for Grain Refinement of Al-Mg-Li Sheet

2007 ◽  
Vol 546-549 ◽  
pp. 885-888
Author(s):  
Yu Xuan Du ◽  
Xin Ming Zhang ◽  
Ling Ying Ye ◽  
Zhi Hui Luo
Keyword(s):  
Shear Deformation ◽  
Grain Refinement ◽  
Electron Backscatter Diffraction ◽  
Grain Structure ◽  
Grain Refining ◽  
Metallic Materials ◽  
Inclined Plane ◽  
Fine Grained ◽  
Electron Backscatter ◽  
Backscatter Diffraction

A novel shear-deformation technique, named ‘shear pressing’ (SP), was developed for fabrication of plate-shaped fine grained metallic materials. The principle of SP is that a material is subjected to shear deformation by utilizing pressing with inclined plane dies. A micrometer order grain structure was obtained in an Al-Mg-Li alloy at strain of ε = -2.3 by utilizing this technique. The grain refinement sequences during pressing were examined by electron backscatter diffraction. The enhancement of grain refinement to the Al-Mg-Li alloy was compared with plane strain compression (PSC) at similar strains. The effect of the shear strain on the accelerated grain refining during compressing has been discussed.

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