scholarly journals Strength and Ductility Improvement through Thermomechanical Treatment of Wire-Feed Electron Beam Additive Manufactured Low Stacking Fault Energy (SFE) Aluminum Bronze

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1568
Author(s):  
Ekaterina Khoroshko ◽  
Andrey Filippov ◽  
Sergei Tarasov ◽  
Nikolay Shamarin ◽  
Evgeny Moskvichev ◽  
...  
Keyword(s):  
Electron Beam ◽  
Strain Hardening ◽  
High Strength ◽  
Tensile Tests ◽  
Aluminum Bronze ◽  
Columnar Grains ◽  
Small Grains ◽  
Strength And Plasticity ◽  
Wire Feed ◽  
Strength And Ductility

An as-cast macrostructure of electron beam additively manufactured metallic materials was represented by coarse columnar grains whose axes were inclined at 25° with respect to the substrate’s plane. One part of the as-grown samples was annealed to form a coarse grain microstructure while the other part was pre-deformed by forging and then annealed what allowed obtaining recrystallized microstructures with small grains and multiple annealing twin boundaries. This sample showed both high strength and plasticity during the tensile tests. These tensile tests demonstrated also two-stage stress-strain curves as depended on their strain hardening rates. High and low strain hardening rates corresponded to a twinning-dominated deformation at stage II and dislocation-base deformation at stage III. A submicron size strain-induced grain-subgrain microstructure was formed in the vicinity of a necked zone as a result of combined twinning/dislocation grain refining.

Strain Hardening Modeling of High-Strength Stainless Steel Tube

2011 ◽  
Vol 311-313 ◽  
pp. 2014-2019
Author(s):  
Ruo Dong Lu ◽  
He Yang ◽  
Heng Li ◽  
Ze Kang Wang ◽  
Mei Zhan ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Strain Hardening ◽  
Large Strain ◽  
High Strength ◽  
Tensile Tests ◽  
Steel Tube ◽  
Uniaxial Tensile ◽  
Stainless Steel Tube ◽  
Hardening Models ◽  
Piecewise Functions

By the uniaxial tensile tests of both the arc and tube section samples, the strain hardening curves of 21-6-9 high-strength stainless steel tube(HSST) are obtained. Considering that the uniform plastic deformation stage of the curve is short and the flow stress in large strain area is unknown for this tube, different strain hardening models have been established based on single and piecewise functions, respectively. By comparing the experimental results and the numerical ones in terms of load-displacement curves, it shows the constitutive model achieved by three Swift fitting functions can better characterize the strain hardening response of the 21-6-9 HSST in large strain region.

Microstructure and Mechanical Propertiesof Ti/Cu-Cr/S20C and Ti/Cu-Ag/S20C Clad Composites

2013 ◽  
Vol 376 ◽  
pp. 153-157 ◽  
Author(s):  
Jong Su Ha ◽  
Sun Ig Hong
Keyword(s):  
Heat Treatment ◽  
High Pressure ◽  
Strain Hardening ◽  
Intermetallic Compounds ◽  
Mechanical Performance ◽  
High Strength ◽  
Strengthening Mechanism ◽  
Reaction Products ◽  
Heat Treated ◽  
Strength And Ductility

In this study Cu-Ag or Cu-Cr layer was sandwiched by Ti and Fe plates and the three layers of Ti/Cu-8Ag/S20C were clad by High Pressure Torsioning(HPT). The effect of post-HPT heat treatment on the interfacial reaction products and the mechanical performance in Ti/Cu-Ag/S20C and Ti/Cu-Cr/S20C clad material were studied. Cu4Ti3 and Cu4Ti Intremetallic compound layers were observed at the Ti/Cu-Ag and Ti/Cu-Cr interfaces in the clad heat-treated at 500°C where as no intermetallic compounds were observed at the Cu-Ag/S20C and Cu-Cr/S20C interfaces. The strength of as-HPTed Ti/Cu-8Ag/S20C is much higher than that of Ti/Cu-1Cr/S20C. The strengthening mechanism of Cu-Ag deformed severely is the interface and strain hardening in which dislocations are deposited at the Cu/Ag interfaces and can contribute to the strengthening of the clad composite just after HPT processing, rendering the high strength just after processing. In both clad composites, the strength and ductility increased after heat treatment at 350°C, which are likely caused by the enhanced bonding at the interfaces.

Effect of Prestrain on Precipitation Behaviors of Ti-2.5Cu Alloy

2018 ◽  
Vol 37 (5) ◽  
pp. 487-493 ◽  
Author(s):  
Zhang Lincai ◽  
Ding Xiaoming ◽  
Ye Wei ◽  
Zhang Man ◽  
Song Zhenya
Keyword(s):  
Precipitation Hardening ◽  
High Strength ◽  
Tensile Tests ◽  
Precipitation Kinetics ◽  
Cu Alloy ◽  
Hcp Materials ◽  
Transmitting Electron Microscopy ◽  
High Temperature Components ◽  
Strength And Plasticity ◽  
Duplex Aging

AbstractAs a special hardenable α titanium alloy, Ti-2.5 Cu alloy was a candidate material for high temperature components requiring high strength and plasticity. The effect of prestrain on the precipitation behaviors was investigated in the present study. Tensile tests show that elongation up to 22 % can be obtained after solid solution (SS) treatment. Thereafter, prestrain in tension with 5 %, 10 %, 15 % and 20 % was carried out for the SS samples and then duplex aging was applied. Transmitting electron microscopy (TEM) investigations show that larger Ti2Cu particles were observed in the prestrained condition than free aging one, as prestrain significantly speeds up the precipitation kinetics. The strength firstly increases and then decreases for the prestrained samples after duplex aging, where the competition between precipitation hardening and recovery softening should be responsible. With the consideration of SS, precipitation and recovery, a strength model for duplex aging combined with prestrain was established, which is in well agreement with experiments. Present study may provide a promising way to obtain the strength of deformed hcp materials in industry application.

scholarly journals Excellent mechanical properties of taenite in meteoric iron

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shohei Ueki ◽  
Yoji Mine ◽  
Kazuki Takashima
Keyword(s):  
Mechanical Properties ◽  
Nitrogen Solubility ◽  
High Strength ◽  
Tensile Tests ◽  
Metallographic Analysis ◽  
Advanced High Strength Steel ◽  
Analysis Techniques ◽  
Solid Solution Strengthening ◽  
Solution Strengthening ◽  
Strength And Ductility

AbstractMeteoric iron is the metal that humans first obtained and used in the earliest stage of metal culture. Advances in metallographic analysis techniques have revealed that meteoric iron largely comprises kamacite, taenite, and cohenite, which correspond to ferrite, austenite, and cementite in artificial steel, respectively. Although the mechanical properties of meteoric irons were measured previously to understand their origin and history, the genuine mechanical properties of meteoric iron remain unknown because of its complex microstructure and the pre-existing cracks in cohenite. Using micro-tensile tests to analyse the single-crystalline constituents of the Canyon Diablo meteorite, herein, we show that the taenite matrix exhibits excellent balance between yield strength and ductility superior to that of the kamacite matrix. We found that taenite is rich in nitrogen despite containing a large amount of nickel, which decreases the nitrogen solubility, suggesting that solid-solution strengthening via nitrogen is highly effective for the Fe–Ni system. Our findings not only provide insights for developing advanced high-strength steel but also help understand the mysterious relationship between nitrogen and nickel contents in steel. Like ancient peoples believed that meteoric iron was a gift from the heavens, the findings herein imply that this thought continues even now.

Effects of Retained Austenite Stability on Mechanical Properties of High Strength TRIP Steel

2012 ◽  
Vol 602-604 ◽  
pp. 287-293
Author(s):  
Zhi Feng Li ◽  
Ren Yu Fu ◽  
Qing Shan Li
Keyword(s):  
Mechanical Properties ◽  
Trip Steel ◽  
Retained Austenite ◽  
Mechanical Stability ◽  
High Strength ◽  
Tensile Tests ◽  
Transformation Kinetics ◽  
Austenite Stability ◽  
Kinetics Of ◽  
Strength And Ductility

Mechanical stability of retained austenite and its effect on mechanical properties of high strength TRIP steel were studied by means of OM, SEM, TEM, XRD, and mechanical testing after various heat treatments. Results revealed that the film-type retained austenite located between bainite laths with high carbon content showed gradual martensitic transformation with strain, demonstrating a good TRIP effect. Samples annealed at 800°C and held at 420°C showed an optimum value of strength and ductility product up to 18381.2MPa%. Transformation kinetics of the retained austenite were evaluated through tensile tests and fitted by the function y=0.86-0.86×exp(-Ax). The fitting results were good.

Effect of Nitrogen Content and Cooling Rate on Transformation Characteristics and Mechanical Properties for 600 MPa High Strength Rebar

2016 ◽  
Vol 35 (9) ◽  
pp. 905-912 ◽  
Author(s):  
Jing Zhang ◽  
Fu-ming Wang ◽  
Chang-rong Li ◽  
Zhan-bing Yang
Keyword(s):  
Nitrogen Content ◽  
Cooling Rate ◽  
Volume Fraction ◽  
High Strength ◽  
Tensile Tests ◽  
Comparative Investigation ◽  
Bainite Transformation ◽  
Performance Requirement ◽  
Nitrogen Contents ◽  
Strength And Ductility

AbstractTo obtain appropriate chemical composition and thermo-mechanical schedules for processing the V-N microalloyed 600 MPa grade high strength rebar, the microstructure analysis during dynamic continuous cooling and tensile tests of three experimental steels with different nitrogen contents were conducted. The results show that increasing nitrogen content promotes ferrite transformation and broadens the bainite transformation interval, when the nitrogen content is in the range of 0.019–0.034 mass%. Meanwhile, the martensite start temperatures decrease and the minimal cooling rate to form martensite increases. To achieve a good combination of strength and ductility, the cooling rates should be controlled in the range of 0.5–3°C/s, leading to the microstructure of ferrite, pearlite and less than 10% bainite (volume fraction). Furthermore, all the experimental steels satisfy the performance requirement of 600 MPa grade rebar and the rebar with nitrogen content of 0.034 mass% shows the highest strength through systematically comparative investigation.

scholarly journals Growth and Deformation Simulation of Aluminum Bronze Grains Produced by Electron Beam Additive Manufacturing

Metals ◽  
2022 ◽  
Vol 12 (1) ◽  
pp. 114
Author(s):  
Anton Yu. Nikonov ◽  
Dmitry V. Lychagin ◽  
Artem A. Bibko ◽  
Olga S. Novitskaya
Keyword(s):  
Electron Beam ◽  
Electron Beam Melting ◽  
Structural Changes ◽  
Shape Change ◽  
Structural Characteristics ◽  
Aluminum Bronze ◽  
Columnar Grains ◽  
Individual Grains ◽  
The Relationship ◽  
Working Out

When working out 3D building-up modes, it is necessary to predict the material properties of the resulting products. For this purpose, the crystallography of aluminum bronze grains after electron beam melting has been studied by EBSD analysis methods. To estimate the possibility of sample form changes by pressure treatment, we simulated structural changes by the method of molecular dynamics during deformation by compression of individual grains of established growth orientations. The analysis was carried out for free lateral faces and grain deformation in confined conditions. Simulation and experiments on single crystals with free lateral faces revealed the occurrence of stepwise deformation in different parts of the crystal and its division into deformation domains. Each domain is characterized by a shear along a certain slip system with the maximum Schmidt factor. Blocking the shear towards the lateral faces leads to selectivity of the shear along the slip systems that provide the required shape change. Based on the simulation results, the relationship between stress–strain curves and structural characteristics is traced. A higher degree of strain hardening and a higher density of defects were found upon deformation in confined conditions. The deformation of the columnar grains of the built material occurs agreed with the systems with the maximum Schmidt factor.

Phase Transformation of Biomedical Metastable β Titanium Alloy during Aging

2009 ◽  
Vol 610-613 ◽  
pp. 1168-1173
Author(s):  
Ai Hong Guo ◽  
Wen Fang Cui ◽  
Yi Zhou Wu ◽  
Xiang Hong Liu ◽  
Lian Zhou
Keyword(s):  
Phase Transformation ◽  
Elastic Modulus ◽  
Biomedical Application ◽  
High Strength ◽  
Tensile Tests ◽  
High Plasticity ◽  
Aging Condition ◽  
Β Phase ◽  
Low Elastic Modulus ◽  
Strength And Plasticity

A kind of metastable β type Ti-30Nb-13Zr-0.5Fe (wt.%) alloy for biomedical application was newly designed and developed. In order to exam the phase transformation during aging and its effects on the mechanical properties, the alloy was β solubilized and aged at 350°C-550°C for 4 hours. The microstructures were observed by OM and TEM, and the phase structures were identified by XRD. The tensile tests were performed with various aged microstructures. The results show that a lot of ω phase precipitates during aging at 350°C, leading to the increase of strength and elastic modulus and drastic decrease of plasticity. Aging at 450°C, dot α phase uniformly precipitates from metastable β phase. The good combination of high strength 、high plasticity and low elastic modulus was obtained under this aging condition. With increasing aging temperature and aging time α precipitations coarsen and precipitation free zones (PFZ) along prior β grain boundaries form, which are the main reasons to lower the strength and plasticity.

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