Hot Workability of a High Strength Low Alloy Steel for Construction Application

2012 ◽  
Vol 724 ◽  
pp. 178-181
Author(s):  
Woo Young Jung ◽  
Tae Kwon Ha
Keyword(s):  
Strain Rate ◽  
Power Dissipation ◽  
High Efficiency ◽  
Hsla Steel ◽  
High Strength ◽  
Plastic Instability ◽  
Strain Rate Range ◽  
Hot Workability ◽  
Compression Tests ◽  
Increasing Temperature

The hot deformation behavior of a high strength low alloy (HSLA) steel for construction application under hot working conditions in the temperature range of 900 to 1100 and strain rate range from 0.1 to 10 s-1 has been studied by performing a series of hot compression tests. The dynamic materials model has been employed for developing the processing maps, which show variation of the efficiency of power dissipation with temperature and strain rate. Also the Kumars model has been used for developing the instability map, which shows variation of the instability for plastic deformation with temperature and strain rate. The efficiency of power dissipation increased with decreasing strain rate and increasing temperature. High efficiency of power dissipation over 20 % was obtained at a finite strain level of 0.3 under the conditions of strain rate lower than 1 s-1 and temperature higher than 1050. Plastic instability was expected in the regime of temperatures lower than 1000°C and strain rate lower than 0.3 s-1.

Strain Rate Sensitivity of Ultrafine-Grained CP-Ti Processed by ECAP at Room Temperature

2010 ◽  
Vol 667-669 ◽  
pp. 707-712 ◽  
Author(s):  
Xiao Yan Liu ◽  
Xi Cheng Zhao ◽  
Xi Rong Yang
Keyword(s):  
Strain Rate ◽  
Strain Rate Sensitivity ◽  
Room Temperature ◽  
Rate Sensitivity ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Ultrafine Grained ◽  
Die Set ◽  
Increasing Temperature ◽  
Cp Ti

Ultrafine-grained (UFG) commercially pure (CP) Ti with a grain size of about 200 nm was produced by ECAP up to 8 passes using route BC at room temperature. For ECAP processing a proper die set was designed and constructed with an internal channel angle Φ of 120° and an outer arc of curvature Ψ of 20°. Strain rate sensitivity of UFG CP-Ti and CG CP-Ti were investigated by compression tests in the temperature range of 298~673K and strain rate range of 10-4~100s-1 using Gleeble simulator machine. Evolution of the microstructure during compression testing was observed using optical microscopy (OM) and transmission electron microscopy (TEM). Strain rate sensitivity value m of the UFG CP-Ti has been measured and is found to increase with increasing temperature and decreasing strain rate, and is enhanced compared to that of CG CP-Ti. Result of the deformation activation energy determination of UFG CP-Ti indicates that the deformation mechanism in UFG CP-Ti is correlated to the grain boundaries.

Hot Workability Analysis of Extruded Mg-Zn-Mn-Y Magnesium Alloys with Different Phases

2012 ◽  
Vol 184-185 ◽  
pp. 1010-1016
Author(s):  
Wei Wei He ◽  
Kun Zhang ◽  
Min Huang ◽  
Sheng Long Dai
Keyword(s):  
Strain Rate ◽  
Magnesium Alloys ◽  
Power Dissipation ◽  
Rate Sensitivity ◽  
Processing Maps ◽  
Hot Workability ◽  
Compression Tests ◽  
Secondary Phases ◽  
Forming Process ◽  
Power Dissipation Efficiency

Workability, an important parameter in magnesium alloys forming process, can be evaluated by means of processing maps on the basis of dynamic materials model, constructed from experimentally generated flow stress variation with respect to strain, strain rate and temperature. To obtain the processing maps of extruded Mg-Zn-Mn-Y magnesium alloy with different secondary phases (I-phase and W-phase), hot compression tests were performed over a range of temperatures 523–673 K and strain rates 0.001~10s-1. The response of strain-rate sensitivity (m-value), power dissipation efficiency (ζ-value) and instability parameter (n-value) to temperature and strain rate were evaluated. By the superimposition of the power dissipation and the instability maps, the dynamic recrystallization (DRX) and instability zones were identified and validated through micrographs. The observations were performed in order to describe the behavior of the material under hot forming operation in terms of material damage and micro-structural modification.

Processing Maps for TC18 Titanium Alloy Deformed in α+β Region

2012 ◽  
Vol 490-495 ◽  
pp. 3423-3426 ◽  
Author(s):  
Xin Zhao ◽  
Hong Zhao ◽  
Rui Zhang
Keyword(s):  
Titanium Alloy ◽  
Strain Rate ◽  
Power Dissipation ◽  
Strain Rate Range ◽  
Hot Working ◽  
Maximum Efficiency ◽  
Processing Maps ◽  
Compression Tests ◽  
Rate Range ◽  
Temperature Range

The hot deformation characteristics of TC18 titanium alloy were studied in the temperature range 750-850°C and strain rate range 0.001-1 s-1 by using hot compression tests. Processing maps for hot working are developed on the basis of the variations of efficiency of power dissipation with temperature and strain rate. The results reveal that the flow stress of TC18 is sensitive to strain rate. Processing map at stain of 0.6 reveals two domains: one is centered at 750°C and 0.001s-1; another is centered at 850°C and 0.001s-1. The maximum efficiency is more than 60%. According to the maps, the zone with the temperature range of 750-850°C and strain rate range of 0.01-0.001s-1 may be suitable for hot working

Hot Deformation and Processing Maps of a High Strength Alloy Steel

2010 ◽  
Vol 97-101 ◽  
pp. 374-377 ◽  
Author(s):  
Yong Cheng Lin ◽  
Ge Liu
Keyword(s):  
Strain Rate ◽  
Alloy Steel ◽  
Power Dissipation ◽  
Hot Deformation ◽  
High Strength ◽  
Strain Rate Range ◽  
Strain Rates ◽  
Low Alloy Steel ◽  
Average Grain Size ◽  
Forming Temperature

The hot deformation behaviors of a high strength low alloy steel have been studied using the processing map technique, which is based on the variations of efficiency of power dissipation with forming temperatures and strain rates. The results show that: (1) The average grain size of the deformed alloy steel increases with the increase of forming temperatures and decreases with the increase of strain rates. (2) The efficiency of power dissipation increases as the forming temperature is increased. However, the efficiency of power dissipation changes with strain rates in the form of bulgy parabola, and the maximum value exists at the strain rate of 0.1 . (3) A domain for reasonable dynamic recrystallization (DRX) exists in the temperature range of (1050–1150) and strain rate range of (0.01–3) , with its peak efficiency of 32% at about 1140 °C and 0.23 , which are the optimum hot working parameters for the studied high strength low alloy steel.

Hot Deformation and Processing Maps of 7005 Aluminum Alloy

2014 ◽  
Vol 33 (4) ◽  
pp. 369-375 ◽  
Author(s):  
Mingliang Wang ◽  
Peipeng Jin ◽  
Jinhui Wang
Keyword(s):  
Strain Rate ◽  
Power Dissipation ◽  
Flow Instability ◽  
Shear Bands ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Instability Map ◽  
Flow Stress Data ◽  
Corrected Flow ◽  
Microstructural Examination

AbstractThe deformation behavior of 7005 alloy was studied by hot compression tests. The processing map was constructed by superimposing the instability map over the power dissipation map at a strain of 0.7 using the corrected flow stress data to eliminate the effect of friction. Microstructural examination was performed for validation. It can be found that the flow stresses increase with the decrease of deformation temperature or the increase of strain rate. At the relatively high strain rates, the material exhibits flow instability manifesting as adiabatic shear bands or flow localization. A large volume of coarse precipitations distributing in the grain boundaries in one of the peak efficiency domains: 275–325 °C/0.0005–0.001 s−1, which may result in inter-granular corrosion and spalling layer, should be avoided in the final deformed alloy. The optimum hot working domain is the temperature range of 400–450 °C and strain rate range of 0.0005–0.005 s−1, at which DRX is identified.

Deformation Behavior of An O + β0 Processed Ti-21 Ai-23Nb Alloy at High Temperatures

1994 ◽  
Vol 364 ◽  
Author(s):  
Venkat Seetharaman
Keyword(s):  
Strain Rate ◽  
High Temperatures ◽  
High Volume ◽  
Strain Rate Range ◽  
Dynamic Strain ◽  
Initial Structure ◽  
Hot Workability ◽  
Compression Tests ◽  
Nominal Strain Rate ◽  
Heat Treated

AbstractA hot workability study was conducted on an orthorhombic Ti-21AI-23Nb alloy using isothermal, constant velocity compression tests, over the temperature range 900–1155°C and nominal strain rate range 0.001 to 1.0 s−1. Three different microstructures corresponding to (a) hot rolled and mill annealed, (b) β0 -heat treated, and (c) β0 solution treated and direct aged conditions were examined. These microstructures varied from a relatively coarse distribution of O-phase precipitates in a matrix of transformed βO to the metastable retained βO. Flow stress displayed a sharp dependence on temperature, strain rate and on the initial structure. While uniform plastic flow was obtained at high temperatures and for structures containing primary O, βO-heat treated structures led to pronounced flow softening. Strong yield point phenomena and serrated flow were observed in selected test conditions and for microstructures containing high volume fractions of metastable βO. These flow instabilities resulting from Luder band propagation and dynamic strain aging are interpreted in terms of dislocation interactions in supersaturated βO.

scholarly journals Compressive Deformation Behavior of Thick Micro-Alloyed HSLA Steel Plates at Elevated Temperatures

2017 ◽  
Vol 62 (2) ◽  
pp. 1191-1196
Author(s):  
J.-H. Lee ◽  
D.-O. Kim ◽  
K. Lee
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Deformation Behavior ◽  
Elevated Temperatures ◽  
Hsla Steel ◽  
High Strength ◽  
Steel Plates ◽  
Compression Tests ◽  
Rate Dependent ◽  
Strength Constant

Abstract The hot deformation behavior of a heavy micro-alloyed high-strength low-alloy (HSLA) steel plate was studied by performing compression tests at elevated temperatures. The hot compression tests were carried out at temperatures from 923 K to 1,223 K with strain rates of 0.002 s−1 and 1.0 s−1. A long plateau region appeared for the 0.002 s−1 strain rate, and this was found to be an effect of the balancing between softening and hardening during deformation. For the 1.0 s−1 strain rate, the flow stress gradually increased after the yield point. The temperature and the strain rate-dependent parameters, such as the strain hardening coefficient (n), strength constant (K), and activation energy (Q), obtained from the flow stress curves were applied to the power law of plastic deformation. The constitutive model for flow stress can be expressed as σ = (39.8 ln (Z) – 716.6) · ε(−0.00955ln(Z) + 0.4930) for the 1.0 s−1 strain rate and σ = (19.9ln (Z) – 592.3) · ε(−0.00212ln(Z) + 0.1540) for the 0.002 s−1 strain rate.

Processing Map of Mg-13Al-3Ca-3Zn-1Nd-0.2Mn Magnesium Alloy

2014 ◽  
Vol 941-944 ◽  
pp. 48-53
Author(s):  
Wei Chen ◽  
Gang Chen ◽  
Jing Zhai ◽  
Li Ma
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Power Dissipation ◽  
Processing Map ◽  
Strain Rate Range ◽  
Compression Tests ◽  
Temperature Range ◽  
Suitable Temperature ◽  
Instability Map ◽  
Flow Stress Data

Compression tests of Mg-13Al-3Ca-3Zn-1Nd-0.2Mn Magnesium alloy as-extruded had been performed in the compression temperature range from 200°C to 400°C and the strain rate range from 0.001 s−1 to 10 s−1 and the flow stress data obtained from the tests were used to develop the power dissipation map, instability map and processing map. The most unsuitable zones in the power dissipation map including 200°C - 315°C and 0.01s-1- 0.1s-1 zone, 315°C - 400°C and 0.001s-1- 0.01s-1zone and 340°C - 360°C and 0.32 s-1- 0.56 s-1zone. The most unsuitable zones in the instability map are 310°C - 400°C, 0.001s-1to 0.56 s-1zone and 330°C - 400°C, 1s-1to 10 s-1zone. The most suitable temperature range is 330°C - 400°C and most optimal strain rate ranges are 1 s-1- 10 s-1and 0.001s-1- 0.56 s-1.

scholarly journals Hot Workability of 300M Steel Investigated by In Situ and Ex Situ Compression Tests

Metals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 880 ◽  
Author(s):  
Rongchuang Chen ◽  
Haifeng Xiao ◽  
Min Wang ◽  
Jianjun Li
Keyword(s):  
Flow Stress ◽  
Strain Rate ◽  
Hot Working ◽  
Ex Situ ◽  
Lower Strain Rate ◽  
Hot Workability ◽  
Compression Tests ◽  
300M Steel ◽  
Lower Strain

In this work, hot compression experiments of 300M steel were performed at 900–1150 °C and 0.01–10 s−1. The relation of flow stress and microstructure evolution was analyzed. The intriguing finding was that at a lower strain rate (0.01 s−1), the flow stress curves were single-peaked, while at a higher strain rate (10 s−1), no peak occurred. Metallographic observation results revealed the phenomenon was because dynamic recrystallization was more complete at a lower strain rate. In situ compression tests were carried out to compare with the results by ex situ compression tests. Hot working maps representing the influences of strains, strain rates, and temperatures were established. It was found that the power dissipation coefficient was not only related to the recrystallized grain size but was also related to the volume fraction of recrystallized grains. The optimal hot working parameters were suggested. This work provides comprehensive understanding of the hot workability of 300M steel in thermal compression.

Critical Strain for the Initiation of Dynamic Recrystallization in a Ni-Fe Base Alloy

2004 ◽  
Vol 449-452 ◽  
pp. 577-580
Author(s):  
Young Sang Na ◽  
Young Mok Rhyim ◽  
J.Y. Lee ◽  
Jae Ho Lee
Keyword(s):  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Critical Strain ◽  
Base Alloy ◽  
Strain Rate Range ◽  
Boundary Phase ◽  
Alloy 718 ◽  
Compression Tests ◽  
Temperature Range ◽  
Critical Strains

In order to quantitatively analyze the critical strain for the initiation of dynamic recrystallization in Ni-Fe-based Alloy 718, a series of uniaxial compression tests was conducted in the temperature range 927°C - 1066°C and the strain rate range 5 x 10-4s-1- 5 s-1with varying initial grain size. The critical strains were graphically determined based on one parameter approach and microscopically confirmed. The effect of γ'' (matrix-hardening phase) and δ (grain boundary phase)on the critical strain was simply discussed. The constitutive model for the critical strain of Alloy 718 was constructed using the experimental data obtained from the higher strain rate and the temperature range between 940°C and 1040°C.

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