scholarly journals Initiation of Dynamic Recrystallization of As-Cast N08028 Alloy

2021 ◽  
Author(s):  
Elena Mora ◽  
Aitor Navarro ◽  
Elena Silveira ◽  
Cecilia Poletti ◽  
Joseba Mendiguren ◽  
...  
Keyword(s):  
Nickel Content ◽  
Austenitic Stainless Steels ◽  
Grain Structure ◽  
Strain Rates ◽  
Compression Tests ◽  
Flow Curves ◽  
High Nickel ◽  
High Fatigue ◽  
Final Strain ◽  
Super Austenitic Stainless Steel

The use of high nickel content austenitic stainless steels (SASS) has significantly increased in the last decade. The corrosion and high fatigue resistance of these materials make them suitable for manufacturing oil country tubular goods (OCTG). SASS are processing by forging from casting conditions. Dynamic recovery (DRV) and recrystallization (DRX) of as-cast super austenitic stainless steel, N08028 Alloy, is investigated to study the refining effect from the as-cast grain structure to fully recrystallized austenite due to hot deformation. Both the critical stress and strain for the initiation of DRX are determined using the flow curves. To perform this analysis, hot compression tests are performed at temperatures between 900°C and 1250°C, and strain rates between 0.1 s-1 and 10 s-1, up to 0,8 final strain using a Gleeble®3800 thermomechanical simulator. Subsequently, the Johnson-Avrami-Mehl-Kolmogorow (JMAK) model is used to numerically fit the flow curves and consequently determine the critical strain. No critical points are seen for temperatures under 1100°C. Above this temperature, the JMAK model proves to be valid in all studied strain rates.

Modeling of Flow Curve at High Temperature for a Ti-6Al-4V Alloy

2013 ◽  
Vol 849 ◽  
pp. 195-199
Author(s):  
Jiranuwat Porntadawit ◽  
Vitoon Uthaisangsuk ◽  
Paiboon Choungthong
Keyword(s):  
Process Design ◽  
Deformation Behavior ◽  
Constitutive Models ◽  
Strain Rates ◽  
Compression Tests ◽  
Forming Process ◽  
Flow Curves ◽  
Different Temperatures ◽  
Machine Parts ◽  
Strain Responses

Titanium alloy grade Ti-6Al-4V has been widely applied for many applications such as aircraft structural components, machine parts, and parts for medical equipments. To understand deformation behavior and microstructure evolution of the material during hot forming process is significant for achieving desired dimension and final mechanical properties of a product. In this study, stress-strain responses of the Ti-6Al-4V alloy were investigated using hot compression tests at different temperatures and strain rates. The determined flow curves of the alloy were subsequently calculated according to the constitutive models based on Cingara equation and Shafiei and Ebrahimi equation and compared with the experimental results. By this manner, influences of work hardening and dynamic recrystallization on the hot deformation behavior of material could be described. Accurate prediction of flow curves can considerably improve the forming process design.

Kinetics of Dynamic Recrystallization of 18 Ni Maraging Steels

2016 ◽  
Vol 850 ◽  
pp. 13-20 ◽  
Author(s):  
Ni Li ◽  
Fei Zhao ◽  
Huan Zhang ◽  
Yong Hai Ren
Keyword(s):  
Dynamic Recrystallization ◽  
Peak Stress ◽  
Strain Rates ◽  
Recrystallization Behavior ◽  
Compression Tests ◽  
Flow Curves ◽  
Maraging Steels ◽  
Dynamic Recrystallization Behavior ◽  
Characteristic Values ◽  
Kinetics Of

The dynamic recrystallization behavior of 18 Ni maraging steels was investigated by hot compression tests at temperatures ranging from 900 °C to 1100 °C and strain rates ranging from 0.001 to 1 s-1. Based on the flow curves from the tests, the effects of temperatures and strain rates on the dynamic recrystallization behavior were analyzed. The strain-hardening rates versus stress curves were used to determine to the critical strain, the peak stress (strain), the saturated stress and the steady stress. With the assistance of the process parameters, constitutive equations were obtained and the activation energy was determined to be 413544.96 J/mol. The dependence of the characteristic values on Zener-Hollomon was found. The dynamic recrystallization kinetics model of the tested steels was constructed and the validity was confirmed based on the experimental results.

scholarly journals Microstructure and Hot Deformation Behavior of Twin Roll Cast Mg-2Zn-1Al-0.3Ca Alloy

Materials ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1020 ◽  
Author(s):  
Kristina Kittner ◽  
Madlen Ullmann ◽  
Thorsten Henseler ◽  
Rudolf Kawalla ◽  
Ulrich Prahl
Keyword(s):  
Hot Deformation ◽  
Deformation Behavior ◽  
Flow Instability ◽  
Grain Structure ◽  
Strain Rates ◽  
Compression Tests ◽  
Cast State ◽  
Hot Deformation Behavior ◽  
Twin Roll Cast ◽  
Twin Roll

In the present work, the microstructure, texture, mechanical properties as well as hot deformation behavior of a Mg-2Zn-1Al-0.3Ca sheet manufactured by twin roll casting were investigated. The twin roll cast state reveals a dendritic microstructure with intermetallic compounds predominantly located in the interdendritic areas. The twin roll cast samples were annealed at 420 °C for 2 h followed by plane strain compression tests in order to study the hardening and softening behavior. Annealing treatment leads to the formation of a grain structure, consisting of equiaxed grains with an average diameter of approximately 19 µm. The twin roll cast state reveals a typical basal texture and the annealed state shows a weakened texture, by spreading basal poles along the transverse direction. The twin roll cast Mg-2Zn-1Al-0.3Ca alloy offers a good ultimate tensile strength of 240 MPa. The course of the flow curves indicate that dynamic recrystallization occurs during hot deformation. For the validity range from 250 °C to 450 °C as well as equivalent logarithmic strain rates from 0.01 s−1 to 10 s−1 calculated model coefficients are shown. The average activation energy for plastic flow of the twin roll cast and annealed Mg-2Zn-1Al-0.3Ca alloy amounts to 180.5 kJ/mol. The processing map reveals one domain with flow instability at temperatures above 370 °C and strain rates ranging from 3 s−1 to 10 s−1. Under these forming conditions, intergranular cracks arose and grew along the grain boundaries.

Compressive Flow Behavior of AZ61 Mg Alloy at Elevated Temperatures

2011 ◽  
Vol 311-313 ◽  
pp. 587-590
Author(s):  
Horng Yu Wu ◽  
Pin Hou Sun ◽  
Jie Chen Yan ◽  
Jing Hao Liao ◽  
Feng Jun Zhu ◽  
...  
Keyword(s):  
Structural Changes ◽  
Elevated Temperatures ◽  
Flow Behavior ◽  
Mg Alloy ◽  
Strain Rates ◽  
Compression Tests ◽  
Flow Curves ◽  
Hollomon Parameter ◽  
Compressive Flow ◽  
Az61 Mg Alloy

The flow behavior and associated structural changes of an AZ61 Mg alloy were analyzed by using hot compression tests in the temperature and strain rate ranges of 250–400 °C and 0.001 to 1 s–1, respectively. The stress–strain curves exhibited the trend typical of materials in which deformation is recovery-controlled in the high Z regime (Z is the Zener–Hollomon parameter), while at low strain rates and high T, the flow curves exhibited a softening typical of recrystallization phenomena. Microstructure analysis has been performed to correlate the microstructure changes to the flow behaviors.

Flow Stress Behavior and Deformation Characteristics of Ti-22Al-25Nb Alloys at Elevated Temperature

2005 ◽  
Vol 475-479 ◽  
pp. 825-828
Author(s):  
Xiao Bo Liang ◽  
Shi Qiong Li ◽  
Yun Jun Cheng ◽  
Jian Wei Zhang
Keyword(s):  
Strain Rate ◽  
Dynamic Recovery ◽  
Orthorhombic Phase ◽  
Strain Rates ◽  
Beta Transus ◽  
Compression Tests ◽  
Flow Curves ◽  
Temperature Range ◽  
Softening Mechanism ◽  
Yield Phenomena

The characteristics of deformation of an orthorhombic phase based alloy, Ti-22Al-25Nb (at%), have been studied by hot compression tests in the temperature range of 940-1150°C with the strain rates of 0.01s-1 and 0.1s-1. A flow curves typically controlled by dynamic recovery were observed in the temperature range of 1090-1150 °C for the strain rate of 0.01s-1 , while discontinuous yield phenomena was found for the strain rate of 0.1s-1. The dynamic recovery can be identified by the microstructure characteristics of the deformation specimens. At 1060°C, the temperature of beta transus, the flow curves and microstructure exhibited the same deformation charateristics as that above the beta transus. At the subtransus temperature, a long period of flow softening followed by the steady-state flow can be observed. During the hot deformation, the hard phases α2 and O elongated, subboundary produced followed by cusp formation in the elongated α2 and O phases, the equiaxed morphology phases occurred by B2 phase penetrating along the subboundaries. The softening mechanism was discussed.

Homogenization of Ingot Metallurgy Near-Gamma Titanium Aluminides

1990 ◽  
Vol 213 ◽  
Author(s):  
S.L. Semiatin ◽  
P. Mcquay ◽  
M. Stucke ◽  
W.R. Kerr ◽  
Y-W. Kim ◽  
...  
Keyword(s):  
Phase Field ◽  
Lamellar Structure ◽  
Titanium Aluminides ◽  
Grain Structure ◽  
Ingot Metallurgy ◽  
Gamma Phase ◽  
Strain Rates ◽  
Compression Tests ◽  
Gamma Titanium ◽  
Gamma Titanium Aluminides

ABSTRACTThe elimination of microsegregation and subsequent breakdown of the lamellar structure in near-gamma titanium aluminides was investigated through a series of high temperature homogenization heat treatments and isothermal hot compression tests. The homogenization heat treatment studies revealed that microsegregation could be eliminated after approximately five hours or one and one-half hours at temperatures either 15 C or 40 C, respectively, above the transus in the single phase alpha field. Subsequent attempts to breakdown the coarse prior alpha grain, lamellar structure were successful at low strain rates (∼ 10−3 s−1) and temperatures low in the alpha + gamma phase field, but led to wedge cracking and gross fracture at high strain rates (∼ 1 s−1) high in the alpha + gamma phase field. Subsequent annealing treatments to globularize the hot-worked structure in order to obtain a uniform, fine, and stable grain structure were also identified.

CRONIFER 1925 HMo

Alloy Digest ◽  
1982 ◽  
Vol 31 (3) ◽  
Keyword(s):  
Flue Gas ◽  
Salt Water ◽  
Nickel Content ◽  
Austenitic Stainless Steels ◽  
Heat Treating ◽  
High Nickel ◽  
Plant Equipment ◽  
Resistance To Stress ◽  
The Common ◽  
Strength And Ductility

Abstract CRONIFER 1925 HMo is an austenitic chromium-nickel-molybdenum stainless steel. The high contents of chromium and especially molybdenum make this steel highly resistant to pitting and crevice corrosion. Because of its high nickel content, its resistance to stress-corrosion cracking is considerably higher than that of the common austenitic stainless steels. CRONIFER 1925 HMo has good strength and ductility, high impact values and good weldability. Its applications include heat exchangers for use with salt water, bleaching-plant equipment and flue-gas scrubbers. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: SS-403. Producer or source: Vereingte Deutsche Metallwerke AG.

scholarly journals A Modified Constitutive Model for the Description of the Flow Behavior of the Ti-10V-2Fe-3Al Alloy during Hot Plastic Deformation

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 844 ◽  
Author(s):  
Wang ◽  
Shen ◽  
Zhang ◽  
Ning
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Strain Rate ◽  
Elevated Temperatures ◽  
Flow Behavior ◽  
Strain Rates ◽  
Compression Tests ◽  
Flow Curves ◽  
Deformation Parameters ◽  
Predicted Values

The hot deformation behavior of the aerospace Ti-10-2-3 alloy was investigated by isothermal compression tests at temperatures of 740 to 820 °C and strain rates of 0.0005 to 10 s−1. The results show that the studied alloy is extremely sensitive to deformation parameters, like the temperature and strain rate. The temperature mainly affects the magnitude of flow stress at larger strains, while the strain rate not only affects the value of flow stress but also the shape of the flow curves. At low strain rates, the flow stress increases with strain, followed by a broad peak and then remains almost constant. At high strain rates, the flow curves exhibit a hardening to a sharp peak at small strains, followed by a rapid dropping to a plateau caused by dynamic softening. In order to describe such flow behavior, a constitutive model considering the effect of deformation parameters was developed as an extension of an existing constitutive model. The modified constitutive model (MC) was obtained based on the original constitutive model (OC) by introducing a new parameter to compensate for the error between the experimental data and predicted values. Compared to the original model, the developed model provides a better description of the flow behavior of Ti-10-2-3 alloy at elevated temperatures over the specified deformation domain.

CARPENTER STAINLESS TYPE 305

Alloy Digest ◽  
1982 ◽  
Vol 31 (2) ◽  
Keyword(s):  
Fracture Toughness ◽  
Corrosion Resistance ◽  
Physical Properties ◽  
Stainless Steels ◽  
Nickel Content ◽  
Austenitic Stainless Steels ◽  
Heat Treating ◽  
Cold Forming ◽  
High Nickel ◽  
The Common

Abstract CARPENTER STAINLESS TYPE 305 has higher nickel content than the austenitic stainless steels considered to be in the 18% chromium-8% nickel category. Its high nickel content lowers the rate of strain hardening and, therefore, allows severe cold forming operations without the necessity of intermediate process anneals in comparison to the common 18-8 austenitic grades. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties as well as fracture toughness. It also includes information on corrosion resistance as well as forming, heat treating, machining, and joining. Filing Code: SS-401. Producer or source: Carpenter.

Evolution of Microstructure during Hot Deformation of Pearlitic Steel

2013 ◽  
Vol 753 ◽  
pp. 459-462
Author(s):  
Rama Krushna Sabat ◽  
Sajal Hatwal ◽  
Bharath Dixit ◽  
Satyam Suwas
Keyword(s):  
Dynamic Recrystallization ◽  
Hot Deformation ◽  
Texture Evolution ◽  
Pearlitic Steel ◽  
Strain Rates ◽  
Compression Tests ◽  
Flow Curves ◽  
X Ray ◽  
Deformation Response ◽  
Evolution Of Microstructure

Hot deformation of pearlitic steel was carried out to examine the overall deformation response to micro structural and texture evolution. To understand the mechanisms operative during hot deformation, compression tests were carried out at various temperatures in the range 400 - 600o C and strain rates in the range 0.001-10 s-1. The flow curves were analyzed to examine the occurrence of dynamic recrystallization. The evolution of microstructure and texture of hot deformed sample is analysed using EBSD and X-ray texture goniometer respectively.

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