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Finite element analysis of small-scale hot compression testing
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作者 Patryk Jedrasiak Hugh Shercliff 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2021年第17期174-188,共15页
This paper models hot compression testing using a dilatometer in loading mode.These small-scale tests provide a high throughput at low cost,but are susceptible to inhomogeneity due to friction and temperature gradient... This paper models hot compression testing using a dilatometer in loading mode.These small-scale tests provide a high throughput at low cost,but are susceptible to inhomogeneity due to friction and temperature gradients.A novel method is presented for correcting the true stress-strain constitutive response over the full range of temperatures,strain-rates and strain.The nominal response from the tests is used to predict the offset in the stress-strain curves due to inhomogeneity,and this stress offsetΔσis applied piecewise to the data,correcting the constitutive response in one iteration.A key new feature is the smoothing and fitting of the flow stress data as a function of temperature and strain-rate,at multiple discrete strains.The corrected model then provides quantitative prediction of the spatial and temporal variation in strain-rate and strain throughout the sample,needed to correlate the local deformation conditions with the microstructure and texture evolution.The study uses a detailed series of 144 hot compression tests of a Zr-Nb alloy.While this is an important wrought nuclear alloy in its own right,it also serves here as a test case for modelling the dilatometer for hot testing of high temperature alloys,particularly those with dualα-βphase microstructures(such as titanium alloys). 展开更多
关键词 Finite element analysis Process modelling hot compression testing UPSETTING Zr alloys Ti alloys
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Hot deformation behavior of Fe-29Ni-17Co alloy 被引量:2
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作者 Mohammad YAZDANI Seyed Mehdi ABBASI +1 位作者 Ali Karimi TAHERI Amir MOMENI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第11期3271-3279,共9页
Hot compression tests were carried out on a Fe-29Ni-17Co alloy in the temperature range of 900 ℃ to 1200 ℃ and at strain rates of 0.001-1 s-1. Dynamic recrystallization was found responsible for flow softening durin... Hot compression tests were carried out on a Fe-29Ni-17Co alloy in the temperature range of 900 ℃ to 1200 ℃ and at strain rates of 0.001-1 s-1. Dynamic recrystallization was found responsible for flow softening during hot compression. The flow behavior was successfully analyzed by the hyperbolic sine equation and the corresponding material constants A, n and αwere determined. The value of apparent activation energy was determined as 423 kJ/mol. The peak and steady state strains showed simple power-law dependence on the Zener-Hollomon parameter. The dynamic recrystallization kinetics was analyzed using Avrami equation and the corresponding exponent was determined to be about 2.7. This value, higher than 2 reported in the literatures, is associated with the mechanism of continuous dynamic recrystallization in the studied alloy. The flow curve up to the peak was modeled by the Cingara equation and the strain exponent, c, was determined about 0.85. The higher value of c compared with the value of 0.2 which has been reported for some stainless steels fortified the idea of extended dynamic recovery or continuous dynamic recrystallization in the studied alloy. 展开更多
关键词 hot working dynamic recrystallization hot compression test flow curve MODELING
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Processing map and microstructure evaluation of AA6061/Al_2O_3 nanocomposite at different temperatures 被引量:2
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作者 H.R.EZATPOUR S.A.SAJJADI +2 位作者 M.HADDAD SABZEVAR A.CHAICHI G.R.EBRAHIMI 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第6期1248-1256,共9页
Hot compression behavior of Al6061/Al2O3nanocomposite was investigated in the temperature range of350-500°C andthe strain rate range of0.0005-0.5s-1,in order to determine the optimum conditions for the hot workab... Hot compression behavior of Al6061/Al2O3nanocomposite was investigated in the temperature range of350-500°C andthe strain rate range of0.0005-0.5s-1,in order to determine the optimum conditions for the hot workability of nanocomposite.Theactivation energy of285kJ/mol for the hot compression test is obtained by using hyperbolic sine function.By means of dynamicmaterial model(DMM)and the corresponding processing map,safe zone for the hot workability of AA6061/Al2O3is recognized attemperature of450°C and strain rate of0.0005s-1and at temperature of500°C and the strain rate range of0.0005-0.5s-1,with themaximum power dissipation efficiency of38%.Elongated and kinked grains are observed at400°C and strain rate of0.5s-1due tothe severe deformation. 展开更多
关键词 NANOCOMPOSITE hot compression test processing map dynamic recrystallization instability flow
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Processing map of as-cast 7075 aluminum alloy for hot working 被引量:11
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作者 Guo Lianggang Yang Shuang +1 位作者 Yang He Zhang Jun 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2015年第6期1774-1783,共10页
The true stress-strain curves of as-cast 7075 aluminum alloy have been obtained by isothermal compression tests at temperatures of 300 500 ~C and strain rates of 0.01 10 s i. The plastic flow instability map is establ... The true stress-strain curves of as-cast 7075 aluminum alloy have been obtained by isothermal compression tests at temperatures of 300 500 ~C and strain rates of 0.01 10 s i. The plastic flow instability map is established based on Gegel B and Murthy instability criteria because the deformed compression samples suggest that the combination of the above two instability criteria has more comprehensive crack prediction ability. And the processing map based on Dynamic Mate- rial Model (DMM) of as-cast 7075 aluminum alloy has been developed through a superposition of the established instability map and power dissipation map. In terms of microstructure of the deformed samples and whether plastic flow is stable or not, the processing map can be divided into five areas: stable area with as-cast grain, stable area with homogeneous grain resulting from dynamic recovery, instability area with as-cast grain, instability area with the second phase and instability area with mixed grains. In consideration of microstructure characteristics in the above five areas of the processing map, the stable area with homogeneous grain resulting from dynamic recovery, namely the temperatures at 425465 ℃ and the strain rates at 0.01^-1 s^-1, is suggested to be suitable processing window for the as-cast 7075 aluminum alloy. 展开更多
关键词 As-cast 7075 aluminum alloy hot compression test hot working Processing map Processing window
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Physical Simulation of Hot Deformation and Microstructural Evolution for 42CrMo4 Steel Prior to Direct Quenching 被引量:5
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作者 A H Meysami R Ghasemzadeh +3 位作者 S H Seyedein M R Aboutalebi R Ebrahimi M Javidani 《Journal of Iron and Steel Research International》 SCIE EI CAS CSCD 2009年第6期47-51,共5页
Direct quenching and tempering (DQ-T) of hot rolled steel section has been widely used in steel mill for the sake of improvement of mechanical properties and energy saving. Temperature history and microstructural ev... Direct quenching and tempering (DQ-T) of hot rolled steel section has been widely used in steel mill for the sake of improvement of mechanical properties and energy saving. Temperature history and microstructural evolution during hot rolling plays a major role in the properties of direct quenched and tempered products. The mathematical and physical modeling of hot forming processes is becoming a very important tool for design and development of required products as well as predicting the microstructure and the properties of the components. These models were mostly used to predict austenite grain size (AGS), dynamic, recta-dynamic and static recrystallization in the rods immediately after hot rolling and prior to DQ process. The hot compression tests were carried out on 42CrMo4 steel in the temperature range of 900-1 100 ℃ and the strain rate range of 0. 05-1 s^-1 in order to study the high tempera- ture softening behavior of the steel. For the exact prediction of flow stress, the effective stress-effective strain curves were obtained from experiments under various conditions. On the basis of experimental results, the dynamic recrystallization fraction (DRX), AGS, hot deformation and activation energy behavior were investigated. It was found that the calculated results were in good agreement with the experimental flow stress and microstructure of the steel for different conditions of hot deformation. 展开更多
关键词 42CrMo4 steel hot compression test dynamic recrystallization hot deformation direct quenching physical simulation
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A Comparative Study of Various Flow Instability Criteria in Processing Map of Superalloy GH4742 被引量:4
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作者 Ge Zhou Hua Ding +1 位作者 Furong Cao Beijiang Zhang 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 2014年第3期217-222,共6页
Hot compression tests were conducted on a Gleeble-1500D thermal simulating tester. Based on the deformation behavior and microstructural evolution of superalloy GH4742, different types of instability criteria of Prasa... Hot compression tests were conducted on a Gleeble-1500D thermal simulating tester. Based on the deformation behavior and microstructural evolution of superalloy GH4742, different types of instability criteria of Prasad, Gegel, Malas, Murty and Semiatin were compared, and the physical significance of parameters was analyzed. Meanwhile, the processing maps with different instability criteria were obtained. It was shown that instability did not occur when average power dissipation rate was larger than 50% in the temperature range of 1020- 1130℃, corresponding to the strain rate range of 5 × 10-4-3.2 × 10-3 s-1. The domain is appropriate for the processing deformation of superalloy GH4742. 展开更多
关键词 GH4742 superalloy hot compression tests Flow instability criterion Processing map
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