scholarly journals Tensile Behavior and Deformation Mechanism of Fe-Mn-Al-C Low Density Steel with High Strength and High Plasticity

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 897 ◽  
Author(s):  
Jingyu Pang ◽  
Zhanming Zhou ◽  
Zhengzhi Zhao ◽  
Di Tang ◽  
Juhua Liang ◽  
...  
Keyword(s):  
Solution Treatment ◽  
High Strength ◽  
Total Elongation ◽  
Tensile Behavior ◽  
Gradual Transition ◽  
High Plasticity ◽  
Low Density ◽  
Hardening Behavior ◽  
Transmission Electron ◽  
Strain Hardening Behavior

Tensile behavior and plastic deformation mechanisms of Fe-22.8Mn-8.48Al-0.86C low-density steel were studied in this thesis. After solution treatment 1100 °C for 1 h; the steels obtained an excellent combination in mechanical properties; with tensile strength of 757.4 MPa and total elongation of 68%; which were attributed to the existence of annealing twins in austenite. The present steel presented a multiple stage strain hardening behavior which was associated with the changes of such dislocation substructures. With the increase of strain, the gradual transition from tangled dislocations to dense dislocation walls and microbands was found in (the transmission electron microscopy) TEM microstructures. Due to the influence of the evolution of the microstructure during the deformation process, the work hardening behavior of the experimental steel shows three distinct stages.

Microstructures and Properties of Low-Density High Strength-Toughness Fe-18Mn-9.5Al-0.65C Steel

2015 ◽  
Vol 817 ◽  
pp. 293-298
Author(s):  
Lei Feng Zhang ◽  
Ren Bo Song ◽  
Chao Zhao ◽  
Fu Qiang Yang ◽  
Shuai Qin
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Strain Hardening ◽  
Solution Treatment ◽  
Solution Temperature ◽  
Uniform Structure ◽  
Low Density ◽  
Hardening Behavior ◽  
Strain Hardening Behavior ◽  
Strength And Ductility

With excellent mechanical properties and low density, Fe-Mn-Al-C steel would be the first choice for automotive lightweight design in future. In this paper, microstructural evolution, mechanical properties and strain hardening behavior of Fe-18Mn-9.5Al-0.65C steel before and after solution treatment were investigated. The experimental steel had (α+γ) duplex phase structure, density of 6.82g/cm3and high product of strength and ductility. After hot rolling, the steel showed microstructural morphology of austenite matrix and banded ferrite, tensile strength of over 1000MPa and elongation of 25%. During solution treatment, the tensile strength, as well as the yielding strength, decreased with the increase of solution temperature, while the elongation increased first and then decreased sharply for excessively coarsening of grains. After solution treated at 1000°C for 1h, the elongation reached 44%, and product of strength and ductility was 34GPa·%, which was 36% higher than that of the hot-rolled steel. Excellent comprehensive properties are attributed to the multiple-stage strain hardening behavior during tensile deformation, as well as the crush and separation of banded ferrite to form a uniform structure during solution treatment.

Strain Hardening Behavior Prediction Model For Automotive High Strength Multiphase Steels

2015 ◽  
Vol 86 (12) ◽  
pp. 1574-1582 ◽  
Author(s):  
Antonella Dimatteo ◽  
Valentina Colla ◽  
Gianfranco Lovicu ◽  
Renzo Valentini
Keyword(s):  
Prediction Model ◽  
Strain Hardening ◽  
High Strength ◽  
Behavior Prediction ◽  
Hardening Behavior ◽  
Strain Hardening Behavior ◽  
Multiphase Steels

Large plasticity in magnesium mediated by pyramidal dislocations

Science ◽  
2019 ◽  
Vol 365 (6448) ◽  
pp. 73-75 ◽  
Author(s):  
Bo-Yu Liu ◽  
Fei Liu ◽  
Nan Yang ◽  
Xiao-Bo Zhai ◽  
Lei Zhang ◽  
...  
Keyword(s):  
Energy Efficiency ◽  
Electron Microscope ◽  
Plastic Strain ◽  
Crystal Size ◽  
High Stress ◽  
High Strength ◽  
High Plasticity ◽  
Transmission Electron ◽  
Small Crystal Size

Lightweight magnesium alloys are attractive as structural materials for improving energy efficiency in applications such as weight reduction of transportation vehicles. One major obstacle for widespread applications is the limited ductility of magnesium, which has been attributed to 〈c+a〉 dislocations failing to accommodate plastic strain. We demonstrate, using in situ transmission electron microscope mechanical testing, that 〈c+a〉 dislocations of various characters can accommodate considerable plasticity through gliding on pyramidal planes. We found that submicrometer-size magnesium samples exhibit high plasticity that is far greater than for their bulk counterparts. Small crystal size usually brings high stress, which in turn activates more 〈c+a〉 dislocations in magnesium to accommodate plasticity, leading to both high strength and good plasticity.

scholarly journals Influence of Hot Deformation on the Precipitation Hardening of High-Strength Aluminum AA7075 during Thermo-Mechanical Processing

Metals ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 681
Author(s):  
Emad Scharifi ◽  
Daria Shoshmina ◽  
Stefan Biegler ◽  
Ursula Weidig ◽  
Kurt Steinhoff
Keyword(s):  
Hot Deformation ◽  
Fine Particles ◽  
Solution Treatment ◽  
High Strength ◽  
Dislocation Motion ◽  
Forming Process ◽  
Deformation Degree ◽  
Transmission Electron ◽  
Dislocation Densities ◽  
Material Hardness

The aim of this work was to investigate the effect of hot deformation on the aging behavior of precipitation-hardenable aluminum alloy AA7075 within a novel thermo-mechanical forming process, in order to gain insight into its precipitation kinetics. For this purpose, the material was formed at 420 °C after undergoing solution treatment to different strain levels ranging from 2% to 10% to obtain different dislocation densities. After undergoing hot deformation, aging at 120 °C with different parameters was carried out to improve the material hardness. The resulting material properties and microstructure evolution were characterized afterward using hardness measurements and a transmission electron microscope (TEM). TEM investigations revealed the formation of very fine particles for the material formed at 2%, as well as at 10%, of formed material, which act as effective barriers to dislocation motion. It was found that the response of artificial aging on the deformation degree in hot forming was less than expected due to the thermally activated mechanisms, leading to a decrease in dislocation density. Therefore, a dramatic increase in material hardness with the increase in hot deformation was not observed.

Influence of Various Precipitate Phases on Tensile Properties of an Extruded Mg-Y-Nd Alloy

2014 ◽  
Vol 788 ◽  
pp. 17-22 ◽  
Author(s):  
Bo Song ◽  
Ren Long Xin ◽  
Gang Chen ◽  
Ke Zeng ◽  
Guang Jie Huang ◽  
...  
Keyword(s):  
Yield Strength ◽  
Strain Hardening ◽  
Tensile Properties ◽  
Precipitation Hardening ◽  
High Strength ◽  
Age Hardening ◽  
Hardening Behavior ◽  
Initial Stage ◽  
Strain Hardening Behavior ◽  
Strain Hardening Rate

The high strength of Mg-Y-Nd alloy has been achieved primarily by precipitation hardening. Therefore, it is important to investigate the influence of various precipitate phases on the tensile properties of Mg-Y-Nd alloys. In this study, an extruded Mg-Y-Nd alloy was aged at various temperatures to examine the hardening behaviors. The results showed that the as-extruded alloy exhibited remarkable age hardening response at 210°C due to the precipitation of β’, and slight hardening response at 150°C and 280°C due to the precipitation of β’’ and β, respectively. Furthermore, different precipitates exerted different effects on the tensile properties. In comparison with the as-extruded alloy, the yield strength of the alloys aged at 210 °C and 150 °C was increased by 21 MPa and 8 MPa, respectively, whereas the yield strength of the alloy aged at 280°C was decreased by 30 MPa. The elongation of the alloy aged at 210°C and 150°C was also largely reduced by 3.4% and 2.9%, respectively, while the elongation of the alloy aged at 280°C was only slightly reduced (6.3%). Moreover, compared with the as-extruded alloy, the alloy aged at 210°C and 150°C exhibited lower hardening capacity and higher strain hardening rate at the initial stage, but the strain hardening rate decreased more quickly with the increasing stress. The alloy aged at 280°C exhibited similar strain hardening behavior with the as-extruded alloy. The results in this study provide guidelines for determining the heat treatment parameters for the Mg-Y-Nd alloys to improve their tensile properties.

Microstructure and properties of high-conductivity, super-high-strength Cu–8.0Ni–1.8Si–0.6Sn–0.15Mg alloy

2009 ◽  
Vol 24 (6) ◽  
pp. 2123-2129 ◽  
Author(s):  
Z. Li ◽  
Z.Y. Pan ◽  
Y.Y. Zhao ◽  
Z. Xiao ◽  
M.P. Wang
Keyword(s):  
Electrical Conductivity ◽  
Processing Condition ◽  
Solution Treatment ◽  
High Strength ◽  
High Conductivity ◽  
Age Hardening ◽  
Transmission Electron ◽  
The Matrix ◽  
Strength Alloy ◽  
Evolution Of Microstructure

A high-conductivity and super-high-strength alloy, Cu-8.0Ni-1.8Si-0.6Sn-0.15Mg, has been developed. The processing conditions of the alloy have been investigated. The evolution of microstructure of the alloy on aging has been examined by transmission electron microscopy. The processing condition giving the highest hardness and good electrical conductivity is as follows: solution treatment at 970 °C for 4 h, cold rolling to 60% reduction, and aging at 500 °C for 30 min. The processed alloy has an average tensile strength of 1180 MPa, 0.2% proof strength of 795 MPa, elongation of 2.75%, and average electrical conductivity of 26.5% IACS. Orthorhombic Ni2Si precipitates are responsible for the age-hardening effect. The orientation relationship between the precipitates and the matrix is (110)m(211)p and. DO22 ordering together with spinodal decomposition also contributed to the hardening.

Effect of Solid Solution Treatment on the Microstructure and Properties of Fe-Mn-Al Light-Weight Steel

2014 ◽  
Vol 788 ◽  
pp. 311-316 ◽  
Author(s):  
Fu Qiang Yang ◽  
Ren Bo Song ◽  
Lei Feng Zhang ◽  
Chao Zhao
Keyword(s):  
Solid Solution ◽  
Tensile Strength ◽  
Solution Treatment ◽  
High Strength ◽  
X Ray Diffraction ◽  
Solid Solution Treatment ◽  
Increasing Temperature ◽  
Hot Rolled ◽  
Strain Hardening Behavior ◽  
Strength And Ductility

A study was made of the effects of solid solution treatment on the properties of hot rolled Fe-Mn-Al steel and on the microstructure transformation. In the steel, the austenite matrix and ferrite duplex phases were confirmed by micrographs and X-ray diffraction. It was indicated that the hot rolled Fe-Mn-Al steel (6.55g/cm3 in density) is with mechanical properties of tensile strength 1315.6MPa, elongation 14.60%. The tensile strength decreases with increasing temperature. The tensile test displays an outstanding combination of high strength and ductility at room temperature due to continuous strain hardening behavior. The product of tensile strength and ductility can reach 46.5GPa·%. Solution treatment contributes to the dissolution of precipitate, austenite grain growth and banded ferrite crushing.

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