scholarly journals Microstructure, Tensile, and Creep Behaviors of Ti-22Al-25Nb (at.%) Orthorhombic Alloy with Equiaxed Microstructure

Materials ◽  
2018 ◽  
Vol 11 (7) ◽  
pp. 1244 ◽  
Author(s):  
Wei Wang ◽  
Weidong Zeng ◽  
Yaling Sun ◽  
Haixiong Zhou ◽  
Xiaobo Liang
Keyword(s):  
Aging Temperature ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Heat Treating ◽  
Phase Region ◽  
Isothermal Forging ◽  
Equiaxed Microstructure ◽  
High Temperature Tensile ◽  
Orthorhombic Alloy ◽  
O Phase

This article investigates the tensile and creep behaviors of the Ti-22Al-25Nb (at.%) alloy with equiaxed microstructure. The experimental results show that the equiaxed microstructures are formed by isothermal forging in the α2 + B2 + O phase region, and then heat treating in α2 + B2 + O and B2 + O phase regions. The equiaxed particles are determined by isothermal forging and solution heat treating, and the acicular O phase is obtained by adjusting the aging temperature. The strengths of the alloy are sensitive to the thickness of the secondary acicular O phase. Increase in aging temperature improves strength and reduces the ductility. Deformation of the alloy mainly depends on the volume fraction and deformability of the B2 phase. During the high-temperature tensile deformation, the flow stress decreases with the increasing deformation temperature and increases with the increasing strain rate. The microstructure obtained by higher aging temperature (HT-840) has better creep resistance, due to the coarsening of the secondary acicular O phase.

scholarly journals Improving the Tensile Properties of Additively Manufactured β-Containing TiAl Alloys via Microstructure Control Focusing on Cellular Precipitation Reaction

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 809
Author(s):  
Ken Cho ◽  
Hirotaka Odo ◽  
Keisuke Okamoto ◽  
Hiroyuki Y. Yasuda ◽  
Hirotoyo Nakashima ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Grain Boundaries ◽  
Tensile Properties ◽  
Volume Fraction ◽  
Lamellar Spacing ◽  
Phase Region ◽  
Precipitation Reaction ◽  
Two Phase ◽  
Cellular Precipitation ◽  
High Temperature Tensile

The effect of a two-step heat treatment on the microstructure and high-temperature tensile properties of β-containing Ti-44Al-4Cr (at%) alloys fabricated by electron beam powder bed fusion were examined by focusing on the morphology of α2/γ lamellar grains and β/γ cells precipitated at the lamellar grain boundaries by a cellular precipitation reaction. The alloys subjected to the first heat treatment step at 1573 K in the α + β two-phase region exhibit a non-equilibrium microstructure consisting of the α2/γ lamellar grains with a fine lamellar spacing and a β/γ duplex structure located at the grain boundaries. In the second step of heat treatment, i.e., aging at 1273 K in the β + γ two-phase region, the β/γ cells are discontinuously precipitated from the lamellar grain boundaries due to excess Cr supersaturation in the lamellae. The volume fraction of the cells and lamellar spacing increase with increasing aging time and affect the tensile properties of the alloys. The aged alloys exhibit higher strength and comparable elongation at 1023 K when compared to the as-built alloys. The strength of these alloys is strongly dependent on the volume fraction and lamellar spacing of the α2/γ lamellae. In addition, the morphology of the β/γ cells is also an important factor controlling the fracture mode and ductility of these alloys.

CARPENTER CTS-204P ALLOY (MICRO MELT 20-4)

Alloy Digest ◽  
2010 ◽  
Vol 59 (1) ◽  
Keyword(s):  
Wear Resistance ◽  
Volume Fraction ◽  
Cold Work ◽  
Heat Treating ◽  
Corrosion And Wear ◽  
Corrosion Resistant ◽  
Die Steel ◽  
Powder Metallurgy Process ◽  
Wear And Corrosion ◽  
Metallurgy Process

Abstract Carpenter CTS-204P (Micro Melt 20-4) alloy is a highly wear- and corrosion-resistant, air-hardening martensitic cold-work stainless die steel produced using Carpenter’s Micro-Melt powder metallurgy process. The excellent wear resistance of the alloy is provided by a significant volume fraction of hard vanadium-rich carbides, while the outstanding corrosion resistance of the alloy is obtained as a result of the chromium-rich matrix. This datasheet provides information on composition, physical properties, hardness, and elasticity. It also includes information on corrosion and wear resistance as well as forming, heat treating, and machining. Filing Code: SS-1051. Producer or source: Carpenter Specialty Alloys.

scholarly journals Microstructural Evolution and Refinement Mechanism of a Beta–Gamma TiAl-Based Alloy during Multidirectional Isothermal Forging

Materials ◽  
2019 ◽  
Vol 12 (15) ◽  
pp. 2496 ◽  
Author(s):  
Kai Zhu ◽  
Shoujiang Qu ◽  
Aihan Feng ◽  
Jingli Sun ◽  
Jun Shen
Keyword(s):  
Dynamic Recrystallization ◽  
Microstructural Evolution ◽  
Lamellar Microstructure ◽  
Phase Region ◽  
Second Step ◽  
Electron Backscattered Diffraction ◽  
Isothermal Forging ◽  
Continuous Dynamic Recrystallization ◽  
Mixture Phase ◽  
Refinement Mechanism

Multidirectional isothermal forging (MDIF) was used on a Ti-44Al-4Nb-1.5Cr-0.5Mo-0.2B (at. %) alloy to obtain a crack-free pancake. The microstructural evolution, such as dynamic recovery and recrystallization behavior, were investigated using electron backscattered diffraction and transmission electron microscopy methods. The MDIF broke down the initial near-lamellar microstructure and produced a refined and homogeneous duplex microstructure. γ grains were effectively refined from 3.6 μm to 1.6 μm after the second step of isothermal forging. The ultimate tensile strength at ambient temperature and the elongation at 800 °C increased significantly after isothermal forging. β/B2→α2 transition occurred during intermediate annealing, and α2 + γ→β/B2 transition occurred during the second step of isothermal forging. The refinement mechanism of the first-step isothermal forging process involved the conversion of the lamellar structure and discontinuous dynamic recrystallization (DDRX) of γ grains in the original mixture-phase region. The lamellar conversion included continuous dynamic recrystallization and DDRX of the γ laths and bugling of the γ phase. DDRX behavior of γ grains dominated the refinement mechanism of the second step of isothermal forging.

scholarly journals A High-Strain-Rate Superplasticity of the Al-Mg-Si-Zr-Sc Alloy with Ni Addition

Materials ◽  
2021 ◽  
Vol 14 (8) ◽  
pp. 2028
Author(s):  
Andrey Mochugovskiy ◽  
Anton Kotov ◽  
Majid Esmaeili Ghayoumabadi ◽  
Olga Yakovtseva ◽  
Anastasia Mikhaylovskaya
Keyword(s):  
Strain Rate ◽  
Volume Fraction ◽  
Strain Rate Range ◽  
Zener Pinning ◽  
Nucleation Effect ◽  
Pinning Effect ◽  
Ni Addition ◽  
Elongation To Failure ◽  
Mean Size ◽  
High Temperature Tensile

The current study analyzed the effect of Ni content on the microstructure and superplastic deformation behavior of the Al-Mg-Si-Cu-based alloy doped with small additions of Sc and Zr. The superplasticity was observed in the studied alloys due to a bimodal particle size distribution. The coarse particles of eutectic origin Al3Ni and Mg2Si phases with a total volume fraction of 4.0–8.0% and a mean size of 1.4–1.6 µm provided the particles with a stimulated nucleation effect. The L12– structured nanoscale dispersoids of Sc- and Zr-bearing phase inhibited recrystallization and grain growth due to a strong Zener pinning effect. The positive effect of Ni on the superplasticity was revealed and confirmed by a high-temperature tensile test in a wide strain rate and temperature limits. In the alloy with 4 wt.% Ni, the elongation-to-failure of 350–520% was observed at 460 °C, in a strain rate range of 2 × 10−3–5 × 10−2 s−1.

Effects of Deformation Mode on Resistivity Curve Used for Estimating Martensite Induced in Stainless Steel

2010 ◽  
Vol 638-642 ◽  
pp. 2992-2997 ◽  
Author(s):  
Hidefumi Date
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Linear Relation ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Deformation Mode ◽  
Transformation Process ◽  
Martensite Formation ◽  
Austenitic Phase ◽  
Ε Phase

The martensite induced in three types of austenitic stainless steel, which indicate the different stability of the austenitic phase (γ), were estimated by the resistivity measured during the tensile deformation or compressive deformation at the temperatures 77, 187 and 293 K. The resistivity curves were strongly dependent on the deformation mode. The volume fraction of the martensite (α’) was also affected by the deformation mode. The ε phase, which is the precursor of the martensite and is induced from the commencement of the deformation, decreased the resistivity. However, lots of defects generated by the deformation-induced martensite increased the resistivity. The experimental facts and the results shown by the modified parallelepiped model suggested a complicated transformation process depending on each deformation mode. The results shown by the model also suggested a linear relation between the resistivity and the martensite volume at the region of the martensite formation. The fact denoted that the resistivity is mostly not controlled by the austenite, ε phase and martensite, but by the defects induced due to the deformation-induced martensite.

High-Temperature Tensile Deformation of Glass-Doped 3Y-TZP

2000 ◽  
Vol 83 (12) ◽  
pp. 3095-3099 ◽  
Author(s):  
Philip H. Imamura ◽  
Neal D. Evans ◽  
Taketo Sakuma ◽  
Martha L. Mecartney
Keyword(s):  
High Temperature ◽  
Tensile Deformation ◽  
High Temperature Tensile

Effect of Tailoring Martensite Shape and Spatial Distribution on Tensile Deformation Characteristics of Dual Phase Steels

2017 ◽  
Vol 140 (2) ◽  
Author(s):  
B. Ravi Kumar ◽  
Vishal Singh ◽  
Tarun Nanda ◽  
Manashi Adhikary ◽  
Nimai Halder ◽  
...  
Keyword(s):  
Grain Size ◽  
Spatial Distribution ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Void Formation ◽  
Martensite Phase ◽  
Continuous Annealing ◽  
Dual Phase ◽  
Deformation Characteristics ◽  
Dp Steels

The authors simulated the industrially used continuous annealing conditions to process dual phase (DP) steels by using a custom designed annealing simulator. Sixty-seven percentage of cold rolled steel sheets was subjected to different processing routes, including the conventional continuous annealing line (CAL), intercritical annealing (ICA), and thermal cycling (TC), to investigate the effect of change in volume fraction, shape, and spatial distribution of martensite on tensile deformation characteristics of DP steels. Annealing parameters were derived using commercial software, including thermo-calc, jmat-pro, and dictra. Through selection of appropriate process parameters, the authors found out possibilities of significantly altering the volume fraction, morphology, and grain size distribution of martensite phase. These constituent variations showed a strong influence on tensile properties of DP steels. It was observed that TC route modified the martensite morphology from the typical lath type to in-grain globular/oblong type and significantly reduced the martensite grain size. This route improved the strength–ductility combination from 590 MPa–33% (obtained through CAL route) to 660 MPa–30%. Finally, the underlying mechanisms of crack initiation/void formation, etc., in different DP microstructures were discussed.

scholarly journals Effect of Mo, V and Zr on the microstructure and mechanical properties of Ti2AlNb alloys

2020 ◽  
Vol 321 ◽  
pp. 08003
Author(s):  
Yujun Du ◽  
Xianghong Liu ◽  
Jinshan Li ◽  
Wenzhong Luo ◽  
Yongsheng He ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Melting Process ◽  
Phase Region ◽  
Arc Furnace ◽  
Micro Hardness ◽  
Β Phase ◽  
Before And After ◽  
B2 Phase ◽  
O Phase

Small button ingots of Ti2AlNb alloys with different contents of Mo, V and Zr were melted by vacuum non-consumable arc furnace. Due to the rapid cooling rate during melting process, only β grains without precipitation were observed in most of the button ingots and no regular phenomenon was found. However, when the samples were heated to β phase region and then furnace cooled to room temperate, different morphologies and quantities of primary α phase and second O phase formed from the β grains of different samples. It is suggested that the morphology of α phase was changed from lamellar to quadrilateral with increasing V and the lath O increased with increasing Zr. Besides, the residual β/B2 phase increased with increasing Mo and V. The EDS results showed that Al and Zr were enriched in α phase whereas Nb, Mo and V were enriched in β/B2 phase. The micro-hardness of these samples before and after heat treatment was detected and the micro-hardness increased with increasing Zr and decreasing Mo and V.

Influence of Isothermal Forging Temperature on Microstructure and Tensile Properties of Ti-5.8Al-4.0Sn-4.0Zr-0.7Nb-0.4Si-1.5Ta Near-α Titanium Alloy

2010 ◽  
Vol 97-101 ◽  
pp. 153-157
Author(s):  
Tao Wang ◽  
Hong Zhen Guo ◽  
Jian Hua Zhang ◽  
Ze Kun Yao
Keyword(s):  
Grain Size ◽  
Tensile Strength ◽  
Titanium Alloy ◽  
Tensile Properties ◽  
Room Temperature ◽  
Volume Fraction ◽  
Constant Strain Rate ◽  
Isothermal Forging ◽  
Α Phase ◽  
Transus Temperature

The microstructures and room temperature and 600°C tensile properties of Ti-5.8Al-4.0Sn-4.0Zr-0.7Nb -0.4Si-1.5Ta alloy after isothermal forging have been studied. The forging temperature range was from 850°C to 1075°C, and the constant strain rate of 8×10-3/S-1 was adopted. With the increase of forging temperature, the volume fraction of primary α phase decreased and the lamellar α phase became thicker when the temperatures were in range of 850°C -1040°C; The grain size became uneven and the α phase had different forms when the forging temperature was 1040°C and 1075°C respectively; The tensile strength was not sensitive to the temperature and the most difference was within 20MPa. Tensile strength and yield strength attained to the maximum when temperature was 1020°C; the ductility decreased with the increase of forging temperature, and this trend became more obvious if forging temperature was above the β-transus temperature.

scholarly journals Effect of Reverse-phase Transformation Annealing Process on Microstructure and Mechanical Properties of Medium Manganese Steel

Materials ◽  
2018 ◽  
Vol 11 (9) ◽  
pp. 1633 ◽  
Author(s):  
Yan Zhao ◽  
Lifeng Fan ◽  
Bin Lu
Keyword(s):  
Mechanical Properties ◽  
Phase Transformation ◽  
Volume Fraction ◽  
Lath Martensite ◽  
Phase Region ◽  
Manganese Steel ◽  
Reverse Phase ◽  
Two Phase ◽  
Fine Grain ◽  
Martensite Microstructure

In order to develop a third-generation automobile steel with powerful strength and elongation, we propose a method through high temperature quenching and two-phase region reverse-phase transformation annealing to develop such steel with 0.13% C and 5.4% Mn. To investigate the microstructure evolution and mechanical properties of manganese steel, SEM, XRD and TEM are employed in our experiments. Experimental results indicate that the microstructure after quenching is mainly lath martensite microstructure with average of lath width at 0.5 μm. The components of the steel after along with reverse-phase transformation annealing are ultra-fine grain ferrite, lath martensite and different forms of austenite microstructure. When the temperature at 625 °C, the components of the steel mainly includes lath martensite microstructure and ultra-fine grain ferrite and the fraction of austenite volume is only 5.09%. When the annealing temperature of reverse-phase transformation increase into 650 °C and 675 °C, the austenite appears in the boundary of the ferritic grain boundary and the boundary of lath martensite as the forms of bulk and lath. The phenomenon appears in the bulk of austenite, and the size of is 0.22 μm, 0.3 μm. The fraction of austenite volume is 22.34% at 675 °C and decreases into 9.32% at 700 °C. The components of austenite mainly includes ultra-fine grained ferrite and lath martensite. Furthermore, the density of decreases significantly, and the width of martensite increases into 0.32 μm. In such experimental settings, quenching at 930 °C with 20 min and at 675 °C with 30 min reverse-phase transformation annealing, the austenite volume fraction raises up to 22.34%.

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