Paradox of Strength and Ductility in Metals Processed Bysevere Plastic Deformation

2002 ◽  
Vol 17 (1) ◽  
pp. 5-8 ◽  
Author(s):  
R. Z. Valiev ◽  
I. V. Alexandrov ◽  
Y. T. Zhu ◽  
T. C. Lowe
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Yield Strength ◽  
Mechanical Behavior ◽  
High Strength ◽  
High Ductility ◽  
Elongation To Failure ◽  
Failure Ductility ◽  
Strength And Ductility

It is well known that plastic deformation induced by conventional forming methodssuch as rolling, drawing or extrusion can significantly increase the strength of metalsHowever, this increase is usually accompanied by a loss of ductility. For example, Fig.1 shows that with increasing plastic deformation, the yield strength of Cu and Almonotonically increases while their elongation to failure (ductility) decreases. Thesame trend is also true for other metals and alloys. Here we report an extraordinarycombination of high strength and high ductility produced in metals subject to severeplastic deformation (SPD). We believe that this unusual mechanical behavior is causedby the unique nanostructures generated by SPD processing. The combination ofultrafine grain size and high-density dislocations appears to enable deformation by newmechanisms. This work demonstrates the possibility of tailoring the microstructures ofmetals and alloys by SPD to obtain both high strength and high ductility. Materialswith such desirable mechanical properties are very attractive for advanced structuralapplications.

scholarly journals Influence of Grain Size and Texture on the Yield Strength of Mg Alloys Processed by Severe Plastic Deformation

2014 ◽  
Vol 2014 ◽  
pp. 1-9 ◽  
Author(s):  
Jinbao Lin ◽  
Weijie Ren ◽  
Qudong Wang ◽  
Lifeng Ma ◽  
Yongjun Chen
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Yield Strength ◽  
Severe Plastic Deformation ◽  
Flow Behavior ◽  
Influence Factors ◽  
Mg Alloys ◽  
Processing Conditions ◽  
Strength And Ductility

Severe plastic deformation (SPD) has been widely employed to refine the grain size of Mg alloys, with the main objective to improve the strength and ductility of Mg alloys, since the well-known Hall-Petch equation suggests that a decreased grain size leads to an increased yield strength. However, the yield strength of Mg alloys processed by SPD is often decreased even though the grain size is effectively reduced. The abnormal flow behavior in Mg alloys processed by SPD has attracted great attention although this mechanism is still unclear, due to its complex and extensive influence factors. In this paper, the relationships between the processing conditions, grain refinement, and mechanical properties of the SPD treated Mg alloys are reviewed, with the emphasis on the effects of grain size and texture on the yield strength.

scholarly journals Microstructure and Mechanical Behavior of Al-Mg Composites Synthesized by Reactive Sintering

Metals ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 762 ◽  
Author(s):  
Rub Nawaz Shahid ◽  
Sergio Scudino
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Yield Strength ◽  
Mechanical Behavior ◽  
Intermetallic Compounds ◽  
Metal Matrix ◽  
Stress Model ◽  
Matrix Composites ◽  
Reactive Sintering ◽  
Powder Mixtures

Lightweight metal matrix composites are synthesized from elemental powder mixtures of aluminum and magnesium using pressure-assisted reactive sintering. The effect of the reaction between aluminum and magnesium on the microstructure and mechanical properties of the composites due to the formation of β-Al3Mg2 and γ-Al12Mg17 intermetallics is investigated. The formation of the intermetallic compounds progressively consumes aluminum and magnesium and induces strengthening of the composites: the yield and compressive strengths increase with the increase of the content of intermetallic reinforcement at the expense of the plastic deformation. The yield strength of the composites follows the iso-stress model when the data are plotted as a function of the intermetallic content.

scholarly journals Effect of enhanced weld cooling on the mechanical properties of a structural steel with a yield strength of 700 MPa

2020 ◽  
Vol 2 (11) ◽  
Author(s):  
Juhani Laitila ◽  
Lassi Keränen ◽  
Jari Larkiola
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Fatigue Strength ◽  
Impact Toughness ◽  
Yield Strength ◽  
Uniform Elongation ◽  
High Strength ◽  
Low Alloy Steel ◽  
External Cooling ◽  
Welding Processes

AbstractIn this study, we present the effect of enhanced cooling on the mechanical properties of a high-strength low-alloy steel (having a yield strength of 700 MPa) following a single-pass weld process. The properties evaluated in this study include uniform elongation, impact toughness, yield, tensile and fatigue strengths alongside the cooling time of the weld. With the steel used in this study, the enhanced cooling resulted in a weld joint characterized with excellent cross-weld uniform elongation, yield and fatigue strength. The intensified cooling reduced the time it takes for the weld to reach 100 °C by around 190 s. Not only the fusion line of the weld was less pronounced, but also the grain size of the CGHAZ was greatly refined as a result of the enhanced cooling. The results indicate that combining external cooling to the welding processes can be beneficial for the studied high-strength steel.

scholarly journals Effect of Heat Treatment on Mechanical Properties and Microstructure Morphology of Low-Alloy High-Strength Steel

2016 ◽  
Vol 61 (2) ◽  
pp. 475-480
Author(s):  
K. Bolanowski
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Grain Size ◽  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Yield Strength ◽  
High Strength Steel ◽  
High Strength ◽  
Strengthening Phase ◽  
Average Grain Size

Abstract The paper analyzes the influence of different heat treatment processes on the mechanical properties of low-alloy high-strength steel denoted by Polish Standard (PN) as 10MnVNb6. One of the findings is that, after aging, the mechanical properties of rolled steel are high: the yield strength may reach > 600 MPa, and the ultimate tensile strength is > 700 MPa. These properties are largely dependent on the grain size and dispersion of the strengthening phase in the ferrite matrix. Aging applied after hot rolling contributes to a considerable rise in the yield strength and ultimate tensile strength. The process of normalization causes a decrease in the average grain size and coalescence (reduction of dispersion) of the strengthening phase. When 10MnVNb6 steel was aged after normalization, there was not a complete recovery in its strength properties.

Influence of Severe Plastic Deformation on Mechanical Properties of an AA5024 Alloy

2016 ◽  
Vol 879 ◽  
pp. 1317-1322 ◽  
Author(s):  
Anna Mogucheva ◽  
Diana Yuzbekova ◽  
Tatiana Lebedkina ◽  
Mikhail Lebyodkin ◽  
Rustam Kaibyshev
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Severe Plastic Deformation ◽  
High Strength ◽  
Coarse Grained ◽  
Type B ◽  
Angular Pressing ◽  
Ultrafine Grained ◽  
Elongation To Failure ◽  
Dislocation Strengthening

The paper reports on the effect of severe plastic deformation on mechanical properties of an Al-4.57Mg-0.35Mn-0.2Sc-0.09Zr (in wt. pct.) alloy processed by equal channel angular pressing followed by cold rolling (CR). The sheets of the 5024 alloy with coarse grained (CG) structure exhibited a yield stress (YS) near 410 MPa and an ultimate tensile strength (UTS) of 480 MPa, while the YS and UTS of this material with ultrafine-grained (UFG) structure increased to 530 and 560 MPa, respectively. On the other hand, the elongation to failure decreased by a factor of 2 and 4 after CR and CR following ECAP, respectively. It was shown that dislocation strengthening attributed to extensive CR plays a major role in achieving high strength of this alloy. Besides these macroscopic characteristics, jerky flow caused by the Portevin-Le Chatelier (PLC) instability of plastic deformation was examined. The formation of UFG structure results in a transition from mixed type A+B to pure type B PLC serrations. No such effect on the serrations type was observed after CR.

Effect of Tempering Temperature on Microstructure, Texture and Mechanical Properties of a High Strength Steel

2014 ◽  
Vol 4 (3) ◽  
pp. 33-49 ◽  
Author(s):  
Pradipta Kumar Jena ◽  
K. Siva Kumar ◽  
A.K. Singh
Keyword(s):  
Mechanical Properties ◽  
Yield Strength ◽  
Mechanical Behavior ◽  
High Strength Steel ◽  
High Strength ◽  
Tempering Temperature ◽  
Plane Anisotropy ◽  
Microstructures And Mechanical Properties

This work describes the microstructure, texture and anisotropy in mechanical behavior of a high strength steel in various tempered conditions. The microstructures and mechanical properties change considerably with varying tempering temperatures. The material exhibits low in-plane anisotropy and low anisotropic index in terms of yield strength and elongation with increase in tempering temperature. The anisotropy of the material displays similar behavior to that of the yield strength.

scholarly journals Achieving High Yield Strength and Ductility in As-Extruded Mg-0.5Sr Alloy by High Mn–Alloying

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4176
Author(s):  
Shibo Zhou ◽  
Xiongjiangchuan He ◽  
Peng Peng ◽  
Tingting Liu ◽  
Guangmin Sheng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Yield Strength ◽  
Tensile Yield Strength ◽  
High Yield ◽  
Compressive Yield Strength ◽  
High Yield Strength ◽  
Pinning Effect ◽  
Small Grains ◽  
Strength And Ductility

The effect of Mn on the microstructure and mechanical properties of as-extruded Mg-0.5Sr alloy were discussed in this work. The results showed that high Mn alloying (2 wt.%) could significantly improve the mechanical properties of the alloys, namely, the tensile and compressive yield strength. The grain size of as-extruded Mg-0.5Sr alloys significantly was refined from 2.78 μm to 1.15 μm due to the pinning effect by fine α-Mn precipitates during the extrusion. Moreover, it also showed that the tensile yield strength and the compressive yield strength of Mg-0.5Sr-2Mn alloy were 32 and 40 percent age higher than those of Mg-0.5Sr alloy, respectively. Moreover, the strain hardening behaviors of the Mg-0.5Sr-2Mn alloy were discussed, which proved that a large number of small grains and texture have an important role in improving mechanical properties.

scholarly journals Mechanical Properties of Copper Processed by Equal Channel Angular Pressing

2017 ◽  
Vol 17 (2) ◽  
pp. 124-129
Author(s):  
K. Sülleiová ◽  
B. Ballóková ◽  
M. Besterci ◽  
T. Kvačkaj
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Equal Channel Angular Pressing ◽  
Dynamic Equilibrium ◽  
Pure Copper ◽  
Angular Pressing ◽  
Static Tensile ◽  
Strength And Ductility ◽  
Test Stress

Abstract The development of the nanostructure in commercial pure copper and the strength and ductility after severe plastic deformation (SPD) with the technology of equal channel angular pressing (ECAP) are analysed. Experimental results and analyses showed that both strength and ductility can be increased simultaneously by SPD. The final grain size decreased from the initial 50μm by SPD to 100-300 nm after 10 passes. An increase of the ductility together with an increase of strength caused by SPD are explained by a strong grain refinement and by a dynamic equilibrium of weakening and strengthening, and it is visible on the final static tensile test stress-strain charts.

A Theoretical Composite Model for Studying the Mechanical Properties of Bimodal Nanocrystalline Materials

2014 ◽  
Vol 687-691 ◽  
pp. 4358-4361
Author(s):  
Hui Jun Li ◽  
Rong Yuan Ju ◽  
Ying Guang Liu ◽  
Xiao Dong Mi ◽  
Hong Jian Yu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Grain Size ◽  
Nanocrystalline Materials ◽  
Composite Model ◽  
Constitutive Behavior ◽  
Catastrophic Failure ◽  
Crack Tips ◽  
Positive Effect ◽  
Strength And Ductility

A new theoretical model is proposed to describe the mechanical properties of bimodal nanocrystalline (BNC) materials.In this paper, we have studied the effect of grain size on the constitutive behavior and fracture of BNC materials. During the plastic deformation, dislocations emission from crack tips on the constitutive behavior of BNC materials are also analyzed, it is found that the nanocracks make a positive effect on the strain hardening instead of leading catastrophic failure. Numerical calculations have been carried out according to the model, the results show that the model can describe the enhanced strength and ductility of BNC materials successfully.

scholarly journals Effect of Reduction in Thickness and Rolling Conditions on Mechanical Properties and Microstructure of Rolled Mg-8Al-1Zn-1Ca Alloy

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Yuta Fukuda ◽  
Masafumi Noda ◽  
Tomomi Ito ◽  
Kazutaka Suzuki ◽  
Naobumi Saito ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
High Strength ◽  
Rolling Process ◽  
Rolled Sheet ◽  
Roll Temperature ◽  
Mean Grain Size ◽  
Thick Rolled Sheet ◽  
Hot Rolled ◽  
Strength And Ductility

A cast Mg-8Al-1Zn-1Ca magnesium alloy was multipass hot rolled at different sample and roll temperatures. The effect of the rolling conditions and reduction in thickness on the microstructure and mechanical properties was investigated. The optimal combination of the ultimate tensile strength, 351 MPa, yield strength, 304 MPa, and ductility, 12.2%, was obtained with the 3 mm thick Mg-8Al-1Zn-1Ca rolled sheet, which was produced with a roll temperature of 80°C and sample temperature of 430°C. This rolling process resulted in the formation of a bimodal structure in the α-Mg matrix, which consequently led to good ductility and high strength, exclusively by the hot rolling process. The 3 mm thick rolled sheet exhibited fine (mean grain size of 2.7 μm) and coarse grain regions (mean grain size of 13.6 μm) with area fractions of 29% and 71%, respectively. In summary, the balance between the strength and ductility was enhanced by the grain refinement of the α-Mg matrix and by controlling the frequency and orientation of the grains.

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