Characteristics of Embrittlement in Weather Resistant Steel in Austenite and γ-Ferrite Temperature Range

2011 ◽  
Vol 704-705 ◽  
pp. 847-852
Author(s):  
Xing Jian Gao ◽  
Deng Fu Chen ◽  
Li Wei Song ◽  
Hui Hu ◽  
Xing Lei Yang ◽  
...  
Keyword(s):  
Tensile Deformation ◽  
Flow Behavior ◽  
Strain Analysis ◽  
Casting Process ◽  
Tensile Tests ◽  
Grain Boundary Sliding ◽  
Hot Ductility ◽  
Resistant Steel ◽  
Stress Strain ◽  
Temperature Range

The embrittlement of particular weather resistant steel has been investigated by thermal tensile tests using a Gleeble-1500D system at temperatures range from 600 to 1300°C and at a strain rate of 10-3/s. The specimen was reheated and cooled to the test temperature before the tensile deformation in order to get the mechanical properties subject to the continuous casting process. To make clear the plastic flow behavior in Austenite and γ-Ferrite temperature range of the weather resistant steel, the tensile tests were performed and the results indicate that the stress-strain curves as a function of temperature and with the temperature increased the stress became less, while the hot ductility changed significantly due to the work hardening and recrystallization. All of the strength indices (including yield strength, tensile strength and fracture strength) of the steel increased gradually with decreasing temperature, except for small fluctuations during the γ→α transformation occurred. Special emphases were placed on the hot ductility to clarify the sensitivity of surface cracking during unbending operation and the embrittlement zone occurred in the temperature range between 750 and 1050°C, in which the minimum %R of A was around 22% at 850°C. In the embrittlement zone, the specimens were fractured with little plastic deformation by either grain boundary sliding or by localization of strain in the film proeutectoid ferrite produced by the γ→α transformation. Keywords: Weather Resistant Steel, Embrittlement Zone, Stress-Strain Analysis, Hot Ductility, Fracture Surface.

scholarly journals A Flow Stress Model of 300M Steel for Isothermal Tension

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 252
Author(s):  
Rongchuang Chen ◽  
Shiyang Zhang ◽  
Xianlong Liu ◽  
Fei Feng
Keyword(s):  
Flow Stress ◽  
Constitutive Model ◽  
Tensile Deformation ◽  
Flow Behavior ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Model Parameters ◽  
Average Deviation ◽  
Cross Sectional ◽  
300M Steel

To investigate the effect of hot working parameters on the flow behavior of 300M steel under tension, hot uniaxial tensile tests were implemented under different temperatures (950 °C, 1000 °C, 1050 °C, 1100 °C, 1150 °C) and strain rates (0.01 s−1, 0.1 s−1, 1 s−1, 10 s−1). Compared with uniaxial compression, the tensile flow stress was 29.1% higher because dynamic recrystallization softening was less sufficient in the tensile stress state. The ultimate elongation of 300M steel increased with the decrease of temperature and the increase of strain rate. To eliminate the influence of sample necking on stress-strain relationship, both the stress and the strain were calibrated using the cross-sectional area of the neck zone. A constitutive model for tensile deformation was established based on the modified Arrhenius model, in which the model parameters (n, α, Q, ln(A)) were described as a function of strain. The average deviation was 6.81 MPa (6.23%), showing good accuracy of the constitutive model.

The hot ductility behaviour of C—Mn—Nb—Al steels and its relation to crack propagation during the straightening of concast strand

1980 ◽  
Vol 295 (1413) ◽  
pp. 124-124
Keyword(s):  
Crack Propagation ◽  
Beneficial Effect ◽  
Surface Crack ◽  
Base Composition ◽  
Tensile Tests ◽  
Hot Ductility ◽  
Percentage Reduction ◽  
Temperature Range ◽  
Solution Treated ◽  
Reduction In Area

As most continuous casters used curved moulds, the as-cast strand must have sufficient hot ductility to survive the straightening operation without cracking. The influence of composition on the tendency for surface crack propagation to occur on straightening of concast strand of a commercial C—Mn-Nb-Al grade of steel, has been examined and compared with the hot ductility behaviour as measured by Gleeble tensile tests. Samples of steel with a nominal base composition of 0.15% C, 1.4% Mn, 0.03% Nb, 0.005 % N but having soluble A1 in the range < 0.01-0.07 % and P in the range 0.01-0.03 % have been solution treated to 1330 °C, cooled to test temperature and strained to fracture in the temperature range 1000-700 °C. The percentage reduction in area passed through a minimum in the temperature range 750-800 °C. Of the elements examined, soluble A1 was found to be the most deleterious to ductility for test temperatures above 850 °C. The niobium addition tended to reduce hot ductility most significantly for temperatures below 850 °C. Phosphorus, surprisingly, was found to have a small beneficial effect on hot ductility.

scholarly journals Effects of B on the Hot Ductility of Fe-36Ni Invar Alloy

2019 ◽  
Vol 38 (2019) ◽  
pp. 380-388 ◽  
Author(s):  
Yaxu Zheng ◽  
Fuming Wang ◽  
Changrong Li ◽  
Zhanbing Yang ◽  
Yutian He
Keyword(s):  
Dynamic Recrystallization ◽  
Grain Boundaries ◽  
Secondary Phase ◽  
Grain Boundary Sliding ◽  
Hot Ductility ◽  
Temperature Range ◽  
Area Reduction ◽  
The Poor ◽  
Thermo Calc Software ◽  
Bearing Alloy

AbstractThis work conducted systematic studies on the effect of B on the hot ductility behavior of Fe-36Ni alloy over the temperature range of 900–1,200 °C by use of Gleeble-3500 thermal simulator, Thermo-Calc software, transmission electron microscopy and secondary ion mass spectroscopy. The influencing factors and mechanisms are also discussed in the present work. Results show that all the values of area reduction of the investigated alloy samples are below 60 % in the temperature range of 900–1,000 °C, indicating the poor hot ductility of the investigated alloys in this temperature range. When the grain boundary sliding occurs during the hot tensile processes, the fine secondary phase particles at grain boundaries prevent the occurrence of dynamic recrystallization and promote the nucleation and propagation of cracking simultaneously, resulting in the poor hot ductility of the investigated alloys in this temperature range. In the B bearing alloy, the segregation of B atoms around austenite grain boundaries promotes the solute dragging effects at grain boundaries and strongly inhibits the occurrence of dynamic recrystallization, which increases the brittle temperature to 1,000 °C. When the temperature exceeds 1,050 °C, the occurrence of dynamic recrystallization improves the hot ductility significantly. However, the coarsening of recrystallized grains and the formation of inter dendritic cracks decrease the hot ductility of the alloy gradually when the temperature increases from 1,100 °C to 1,200 °C.

Microstructure Features during High Temperature Tensile Deformation of an AZ31 Alloy with Nd and La Additions

2012 ◽  
Vol 578 ◽  
pp. 158-161
Author(s):  
Jun Qiao ◽  
Min He ◽  
Fu Bo Bian ◽  
Yu Wang ◽  
Qing Feng Zhang ◽  
...  
Keyword(s):  
Dynamic Recrystallization ◽  
Tensile Deformation ◽  
Tensile Tests ◽  
Az31 Alloy ◽  
Grain Boundary Sliding ◽  
Dislocation Creep ◽  
Premature Failure ◽  
Elongation To Failure ◽  
Cavity Evolution ◽  
High Temperature Tensile

Microstructural features and tensile behaviors of an AZ31 alloy with Nd and La additions were investigated with elongation-to-failure tensile tests at constant temperatures of 300 °C, 350 °C, 400 °C, and 450 °C, and constant strain rates of 10-2s-1and 10-3s-1. Experimental data show that the material exhibits tensile ductilities of over 100% at 450 °C, featured by long steady state deformation. Microstructure studies show that annealed coarse grains were remained in the gauge region after the tensile tests, and the dominate deformation mechanism was dislocation creep, other than dynamic recrystallization or grain boundary sliding. Cavity evolution near fracture end caused premature failure of the material, although fine grains developed through dynamic recrystallization.

Effect of Rare Earth Yttrium on the Hot Ductility of Fe-36Ni Invar Alloy

2014 ◽  
Vol 33 (6) ◽  
pp. 531-537 ◽  
Author(s):  
Y. C. Yu ◽  
H. T. Liu ◽  
W. Q. Chen ◽  
H. G. Zheng
Keyword(s):  
Grain Boundary ◽  
Grain Boundaries ◽  
Testing Temperature ◽  
Grain Boundary Sliding ◽  
Substantial Improvement ◽  
Grain Structure ◽  
Invar Alloy ◽  
Hot Ductility ◽  
Temperature Range ◽  
Boundary Sliding

AbstractThe hot ductility of Fe-36Ni invar alloy doped with and without yttrium was investigated using a Gleeble-3800 thermal-mechanical simulator over the temperature range 850–1050 °C and the improvement mechanism of the hot ductility was analysed with a combination of SEM, EDS and OM. The results showed that Fe-36Ni invar alloy had a poor hot ductility below 1050 °C, which was mainly attributed to the presence of the grain boundary sliding and weak grain boundaries. The addition of 0.048% yttrium had a substantial improvement in the hot ductility of Fe-36Ni invar alloy over the whole testing temperature range especially at 950–1000 °C. At 850–900 °C, the improvement of the hot ductility was mainly associated with the grain boundary strengthening and the restriction of the grain boundary sliding because the addition of yttrium could reduce the segregation of sulfur at grain boundaries and refine the grain structure. At 950–1000 °C, the hot ductility was highly improved, which was owed to the acceleration and occurrence of dynamic recrystallization as a result of the refinement of the grain structure by addition of yttrium.

scholarly journals Temperature Effects on Tensile Deformation Behavior of a Medium Manganese TRIP Steel and a Quenched and Partitioned Steel

Metals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 375
Author(s):  
Whitney A. Poling ◽  
Emmanuel De Moor ◽  
John G. Speer ◽  
Kip O. Findley
Keyword(s):  
Trip Steel ◽  
Retained Austenite ◽  
Tensile Deformation ◽  
Flow Behavior ◽  
Uniform Elongation ◽  
High Strength Steels ◽  
Tensile Tests ◽  
Effect Of Temperature ◽  
Austenite Stability ◽  
Increasing Temperature

Third-generation advanced high-strength steels (AHSS) containing metastable retained austenite are being developed for the structural components of vehicles to reduce vehicle weight and improve crash performance. The goal of this work was to compare the effect of temperature on austenite stability and tensile mechanical properties of two steels, a quenched and partitioned (Q&P) steel with a martensite and retained austenite microstructure, and a medium manganese transformation-induced plasticity (TRIP) steel with a ferrite and retained austenite microstructure. Quasi-static tensile tests were performed at temperatures between −10 and 85 °C for the Q&P steel (0.28C-2.56Mn-1.56Si in wt.%), and between −10 and 115 °C for the medium manganese TRIP steel (0.14C-7.14Mn-0.23Si in wt.%). X-ray diffraction measurements as a function of strain were performed from interrupted tensile tests at all test temperatures. For the medium manganese TRIP steel, austenite stability increased significantly, serrated flow behavior changed, and tensile strength and elongation changed significantly with increasing temperature. For the Q&P steel, flow stress was mostly insensitive to temperature, uniform elongation decreased with increasing temperature, and austenite stability increased with increasing temperature. The Olson–Cohen model for the austenite-to-martensite transformation as a function of strain showed good agreement for the medium manganese TRIP steel data and fit most of the Q&P steel data above 1% strain.

scholarly journals Grain Rotation Accommodated GBS Mechanism for the Ti-6Al-4V Alloy during Superplastic Deformation

Crystals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 991
Author(s):  
Junzhou Yang ◽  
Jianjun Wu
Keyword(s):  
Deformation Mechanism ◽  
Superplastic Deformation ◽  
Texture Evolution ◽  
Flow Behavior ◽  
Constant Strain Rate ◽  
Tensile Tests ◽  
Optical Microscope ◽  
Grain Boundary Sliding ◽  
Grain Rotation ◽  
Boundary Sliding

An investigation of flow behavior and the deformation mechanism for Ti-6Al-4V alloy during the superplastic deformation process is presented in this paper. Constant strain rate tensile tests were performed at 890–950 °C and strain rates of 10−2, 10−3, and 10−4/s. Then, surface observation by Optical Microscope (OM), Scanning Electron Microscopy (SEM), and Electron Back-scattered Diffraction (EBSD) was applied to obtain the microstructure mechanism. With pole figure maps (PF) for α-phase, obvious texture gradually changed in the main deformation direction. For the titanium alloy, the evolution of texture in deformed samples was attributed to grain rotation (GR). Significant grain rearrangement occurred between grains after deformation. A complete grain rotation accommodated grain boundary sliding (GBS) deformation mechanism is proposed, which can explain texture evolution without grain deformation.

scholarly journals Visualization of the damage evolution for Ti–3Al–2Mo–2Zr alloy during a uniaxial tensile process using a microvoids proliferation damage model

2021 ◽  
Vol 40 (1) ◽  
pp. 310-324
Author(s):  
Ying Tong ◽  
Jiang Zhao ◽  
Guo-zheng Quan
Keyword(s):  
Plastic Deformation ◽  
Damage Evolution ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Damage Model ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Strain Rates ◽  
Stress Strain ◽  
Gtn Damage Model

Abstract Understanding the damage evolution of alloys during a plastic deformation process is significant to the structural design of components and accident prevention. In order to visualize the damage evolution in the plastic deformation of Ti–3Al–2Mo–2Zr alloy, a series of uniaxial tensile experiments for this alloy were carried out under the strain rates of 0.1–10 s−1 at room temperature, and the stress–strain curves were achieved. On the other hand, the finite element (FE) models of these uniaxial tensile processes were established. A microvoids proliferation model, Gurson–Tvergaard–Needleman (GTN) damage model, was implanted into the uniaxial tensile models, and the simulated stress–strain curves corresponding to different GTN parameter combinations were obtained. Based on the simulated and experimental stress–strain curves, the GTN parameters of this alloy were solved by response surface methodology (RSM). The solved GTN parameters suggest that higher strain rate can enhance the proliferation and coalescence of microvoids. Furthermore, the uniaxial tensile tests over different strain rates were simulated using the solved GTN parameters. Then, the damage processes were visualized and evaluated. The result shows that the degradation speed of this alloy is slow at the initial stage of the tensile deformation and then accelerates once the voids volume fraction reaches a critical value.

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