scholarly journals Tensile Properties of -Oriented Nanotwinned Cu with Different Columnar Grain Structures

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1310
Author(s):  
Yu-Jin Li ◽  
King-Ning Tu ◽  
Chih Chen
Keyword(s):  
Yield Strength ◽  
Factor Model ◽  
Tensile Axis ◽  
Tensile Tests ◽  
Nitrogen Atmosphere ◽  
Theoretical Yield ◽  
Grain Structures ◽  
Average Grain Size ◽  
Schmid Factor ◽  
Columnar Grain

We performed tensile tests on highly <111>-oriented nanotwinned copper (nt-Cu) foils with different columnar grain structures. For a systematic study, we altered the microstructure of the foils by tuning the electroplating electrolyte and annealing temperatures under a nitrogen atmosphere. The results show that the yield strength ranges from 300 to 700 MPa, and elongation spans from 5% to 25%. Knowing the measured twin spacing and average grain size, and combining the confined layer slip with the Hall–Petch equation, we calculated the theoretical yield strength of the nt-Cu with different microstructures, and the theoretic values match the experiment results. Owing to the unique crystal orientation properties of <111>-oriented columnar grains, dislocations induced by slip are very limited. The Schmid factor of grains along the tensile axis direction is highly identical, so the plastic deformation is much more suitably explained by the Schmid factor model. Thus, we replace the Taylor factor with the Schmid factor in the slip model of nt-Cu.

Regularities and properties of instrumented indentation diagrams obtained by ball-shaped indenter

2020 ◽  
Vol 86 (5) ◽  
pp. 43-51
Author(s):  
V. M. Matyunin ◽  
A. Yu. Marchenkov ◽  
N. Abusaif ◽  
P. V. Volkov ◽  
D. A. Zhgut
Keyword(s):  
Yield Strength ◽  
Ultimate Strength ◽  
Elastoplastic Deformation ◽  
Elastic Limit ◽  
Tensile Tests ◽  
Indentation Load ◽  
International Standards ◽  
Instrumented Indentation ◽  
Indentation Methods ◽  
Special Points

The history of appearance and the current state of instrumented indentation are briefly described. It is noted that the materials instrumented indentation methods using a pyramid and ball indenters are actively developing and are currently regulated by several Russian and international standards. These standards provide formulas for calculating the Young’s modulus and hardness at maximum indentation load. Instrumented indentation diagrams «load F – displacement α» of a ball indenter for metallic materials were investigated. The special points on the instrumented indentation diagrams «F – α» loading curves in the area of elastic into elastoplastic deformation transition, and in the area of stable elastoplastic deformation are revealed. A loading curve area with the load above which the dF/dα begins to decrease is analyzed. A technique is proposed for converting «F – α» diagrams to «unrestored Brinell hardness HBt – relative unrestored indent depth t/R» diagrams. The elastic and elastoplastic areas of «HBt – t/R» diagrams are described by equations obtained analytically and experimentally. The materials strain hardening parameters during ball indentation in the area of elastoplastic and plastic deformation are proposed. The similarity of «HBt – t/R» indentation diagram with the «stress σ – strain δ» tensile diagrams containing common zones and points is shown. Methods have been developed for determining hardness at the elastic limit, hardness at the yield strength, and hardness at the ultimate strength by instrumented indentation with the equations for their calculation. Experiments on structural materials with different mechanical properties were carried out by instrumented indentation. The values of hardness at the elastic limit, hardness at the yield strength and hardness at the ultimate strength are determined. It is concluded that the correlations between the elastic limit and hardness at the elastic limit, yield strength and hardness at the yield strength, ultimate tensile strength and hardness at the ultimate strength is more justified, since the listed mechanical characteristics are determined by the common special points of indentation diagrams and tensile tests diagrams.

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.

Correlation among Microstructure, Texture, and Properties along the Thickness Direction in As-Hot-Rolled and As-Solution-Quenched Al7055 Thick Plates

2021 ◽  
Vol 1026 ◽  
pp. 65-73
Author(s):  
Kai Zhu ◽  
Hong Wei Yan
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Tensile Tests ◽  
Rolled Plate ◽  
Uniaxial Tensile ◽  
Thickness Direction ◽  
Electron Backscattered Diffraction ◽  
Thick Plates ◽  
Aluminum Plates ◽  
Hot Rolled

Both microstructure inhomogeneity and mechanical property diversity along the thickness direction in rolled thick aluminum plates have been considered to have a remarkable impact on the performance and properties of the products made from the plates. In this study, scanning electron microscopy (SEM) and electron backscattered diffraction (EBSD) characterizations of microstructure and texture types along the thickness directions of Al7055 thick plate specimens prepared using two conditions, hot-rolling and solution-quenching, were performed. To examine the mechanical properties, uniaxial tensile tests were also carried out on specimens machined from both types of thick plates, using a layered strategy along the thickness direction. The results indicate that both the microstructure and mechanical properties are inhomogeneous under the two conditions. Furthermore, it is evident that there is a hereditary relationship between the mechanical properties of the two plates—areas with higher yield strength in the as-hot-rolled plate correspond to areas with the higher yield strength in the as-solution-quenched plate

Superplastic Behavior of a Cu-Cr-Zr Alloy Subjected to ECAP

2016 ◽  
Vol 838-839 ◽  
pp. 404-409
Author(s):  
Roman Mishnev ◽  
Iaroslava Shakhova ◽  
Andrey Belyakov ◽  
Rustam Kaibyshev
Keyword(s):  
Grain Size ◽  
Dislocation Density ◽  
Strain Rate ◽  
Temperature Interval ◽  
Rate Sensitivity ◽  
Tensile Tests ◽  
Superplastic Behavior ◽  
Average Grain Size ◽  
Gauge Section ◽  
Zr Alloy

A Cu-0.87%Cr-0.06%Zr alloy was subjected to equal channel angular pressing (ECAP) at a temperature of 400 °C up to a total strain of ~ 12. This processing produced ultra-fine grained (UFG) structure with an average grain size of 0.6 μm and an average dislocation density of ~4×1014 m-2. Tensile tests were carried out in the temperature interval 450 – 650 °C at strain rates ranging from 2.8´10-4 to 0.55 s-1. The alloy exhibits superplastic behavior in the temperature interval 550 – 600 °C at strain rate over 5.5´10-3 s-1. The highest elongation-to-failure of ~300% was obtained at a temperature of 575 °C and a strain rate of 2.8´10-3 s-1 with the corresponding strain rate sensitivity of 0.32. It was shown the superplastic flow at the optimum conditions leads to limited grain growth in the gauge section. The grain size increases from 0.6 μm to 0.87 μm after testing, while dislocation density decreases insignificantly to ~1014 m-2.

Microstructure and Mechanical Property of Mg-Sn-Al Wrought Magnesium Alloys

2017 ◽  
Vol 898 ◽  
pp. 97-103 ◽  
Author(s):  
Zheng Hua Huang ◽  
Nan Zhou ◽  
Jing Xu ◽  
Yang De Li ◽  
Wei Rong Li
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Tensile Strength ◽  
Yield Strength ◽  
Ambient Temperature ◽  
Hot Extrusion ◽  
Average Grain Size ◽  
Zk60 Alloy ◽  
Cast Alloys ◽  
Az31b Alloy

The microstructures, phase constitutions and mechanical properties of as-cast samples, extruded rods and plates of Mg-3.52Sn-3.32Al and Mg-6.54Sn-4.78Al alloys were investigated by optical microscopy, scanning electron microscopy, X-ray diffraction and mechanical testing. The results show that as-cast microstructure consists of α-Mg matrix, Mg2Sn and a few dispersed β-Mg17Al12 phases. The two as-cast alloys exhibit good tensile mechanical properties. After hot extrusion, dynamic recrystallization occurs. Average grain size reaches 6 μm ~ 8 μm for rods, and a lot of fine micro-scaled particles exist, resulting in significant enhancement of tensile mechanical properties. The extruded Mg-3.52Sn-3.32Al rod exhibits better comprehensive tensile mechanical property than AZ31B alloy, with tensile strength σb of 295 MPa, yield strength of 200 MPa and elongation of 21.5% at ambient temperature. The extruded Mg-6.54Sn-4.78Al rod exhibits equivalent comprehensive tensile mechanical properties with ZK60 alloy, achieving tensile strength of 355 MPa, yield strength of 275 MPa and elongation of 11% at ambient temperature. The extruded plates at ambient temperature performed a tensile strength of 270 MPa.

Tensile Deformation of Si Single Crystals at High Temperatures

2021 ◽  
Vol 1016 ◽  
pp. 1443-1447
Author(s):  
Tubasa Suzuki ◽  
Masaki Tanaka ◽  
Tatsuya Morikawa ◽  
Yelm Okuyama ◽  
Jun Fujise ◽  
...  
Keyword(s):  
Slip System ◽  
Single Crystals ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Stage Ii ◽  
Electron Backscattered Diffraction ◽  
Kink Bands ◽  
Schmid Factor ◽  
Primary Slip System ◽  
Yield Point Phenomenon

Czochralski silicon single crystals were deformed in tensile tests along the direction at between 1173 K and 1373. Yield point phenomenon were observed in the specimens deformed at below 1273 K while continues yield was observed in the specimens deformed at above 1323 K. It is due to the effect of dislocation starvation in the used crystals. Work-hardening rates in stage II were consistent with those reported in fcc crystals such as copper. The onset of stage II was found to be active before the Schmid factor of the second slip system becomes larger than that of the primary slip system. Electron backscattered diffraction images indicated clear kink bands near grips and in the parallel portion. The kink bands were formed at the middle of stage I, which suggest that the formation of kink bands is a trigger of stage II.

scholarly journals Ductile Cast Iron with High Toughness at Low Temperatures

2018 ◽  
Vol 925 ◽  
pp. 334-341 ◽  
Author(s):  
Stephanie Duwe ◽  
Babette Tonn
Keyword(s):  
Yield Strength ◽  
Low Temperatures ◽  
Charpy Impact ◽  
Tensile Tests ◽  
Ductile Cast Iron ◽  
Fractional Factorial ◽  
Alloy Development ◽  
Static Tensile ◽  
Minimum Criteria ◽  
Optimum Alloy

High life expectancy of cast components and good material performance at dynamic load are a prerequisite to cater for future trends in wind energy generators. To remain competitive in this ever evolving sector challenges reside in alloy development. In this work fractional factorial design has been applied to ferritic ductile iron with varying contents of silicon (1.6‑2 wt%), nickel (0‑1 wt%), cobalt (0‑3 wt%) and copper (0‑0.2 wt%). The minimum criteria the new alloy should meet were a minimum yield strength of 240 MPa and an impact work of minimal 8 J at a temperature of -20 °C for wall thicknesses of 60‑200 mm. To obtain these mechanical properties thick-walled castings with additional insulation were produced to achieve a higher thermic module. They provided the material for test specimens to perform static tensile tests, Charpy impact tests at varying temperatures and a microstructure analysis. With these results, a sweet spot plot has been created. That way, an optimum alloy composition could be found and has been proven by validation experiment.The optimum alloy for thick-walled castings is composed of Si = 1.6 wt%, Cu = 0.2 wt%, Ni = 0 wt% and Co = 0 wt%. It offers an enhancement in yield strength and acceptable impact work at low temperatures for massive castings in as cast state. The heat treated, full ferritic material could even improve these results.

Effect of Artificial Aging on Microstructures and Mechanical Properties of Extruded Mg Alloy ZK60

2014 ◽  
Vol 697 ◽  
pp. 72-75
Author(s):  
De Liang Yin ◽  
Jian Qiao ◽  
Hong Liang Cui
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Aging Time ◽  
Artificial Aging ◽  
Aging Treatment ◽  
Tensile Tests ◽  
Tensile Yield Strength ◽  
Uniaxial Tensile ◽  
Fracture Elongation ◽  
Strength And Ductility

An extruded ZK60 magnesium alloy was subjected to artificial aging at 180 oC for an investigation of the effect of aging time on its precipitation behavior and mechanical properties. Uniaxial tensile tests were conducted to obtain the mechanical properties. Optical microscopy and transmission electron microscopy (TEM) were employed to observe microstructure change before and after aging treatment. It is shown that, both tensile yield strength and ultimate tensile strength increases with aging time. The fracture elongation after aging for 20 h reaches up to 21.0%, and the yield strength increases to 269.5 MPa, 19.4% higher than that of extruded specimens (un-aged), showing a good match of strength and ductility. Three newly-formed precipitates were observed after aging for over 20 h, among which particulate and dispersive precipitates should be responsible for the good combination of strength and ductility.

Evolution of Microstructure during Hot Deformation of the PM Molybdenum Alloy TZM

2007 ◽  
Vol 539-543 ◽  
pp. 2725-2730 ◽  
Author(s):  
T. Mrotzek ◽  
Andreas Hoffmann ◽  
U. Martin ◽  
H. Oettel
Keyword(s):  
Yield Strength ◽  
Hot Deformation ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
High Strength ◽  
Tensile Tests ◽  
Primary Recrystallization ◽  
Molybdenum Alloy ◽  
Texture Formation ◽  
Evolution Of Microstructure

The molybdenum alloy TZM (Mo-0.5wt%Ti-0.08wt%Zr) is a commonly used structural material for high temperature applications. For these purposes a high strength at elevated temperatures and also a sufficient ductility at room temperature are being aimed. Preceding investigations revealed the existence of subgrains in hot deformed TZM. It was observed that with proceeding primary recrystallization and therefore with disappearance of subgrains the yield strength drops almost to a level of pure molybdenum. It is being assumed that the existence of a dislocation substructure has a pronounced effect on the yield strength of TZM. The aim of the present study was to evaluate the subgrain and texture formation and also to estimate the dislocation arrangement within subgrains during hot deformation. Hence, TZM rods were rolled to different degrees of deformation at a temperature above 0.5 Tm. The microstructure of the initial material was fully recrystallized. Texture formation, misorientation distributions and subgrain sizes were analyzed by electron backscattering diffraction (EBSD). Mechanical properties were characterized by tensile tests at room temperature and up to 1200°C. It was revealed, that with increasing degree of deformation a distinct substructure forms and therefore yield strength rises. Consequently, the misorientation between adjacent subgrains increases, their size decreases and a <110> fibre texture develops. To estimate the influence of texture on strength of TZM the Taylor factors are calculated from EBSD data.

Effect of High Temperature Caliber Rolling on Microstructure and Room Temperature Tensile Properties of Mg-3Al-1Zn (AZ31) Alloy

2013 ◽  
Vol 209 ◽  
pp. 6-9 ◽  
Author(s):  
Rajendra Doiphode ◽  
S.V.S. Narayana Murty ◽  
Nityanand Prabhu ◽  
Bhagwati Prasad Kashyap
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Yield Strength ◽  
Strain Rate ◽  
Tensile Properties ◽  
Room Temperature ◽  
Tensile Tests ◽  
Az31 Alloy ◽  
Rolling Temperature ◽  
Grain Sizes

Mg-3Al-1Zn (AZ31) alloy was caliber rolled at 250, 300, 350, 400 and 450 °C. The effects of caliber rolling temperature on the microstructure and tensile properties were investigated. The room temperature tensile tests were carried out to failure at a strain rate of 1 x 10-4s-1. The nature of stress-strain curves obtained was found to vary with the temperature employed in caliber rolling. The yield strength and tensile strength followed a sinusoidal behaviour with increasing caliber rolling temperature but no such trend was noted in ductility. These variations in tensile properties were explained by the varying grain sizes obtained as a function of caliber rolling temperature.

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