The Experts below are selected from a list of 28827 Experts worldwide ranked by ideXlab platform
Guanjun Qiao - One of the best experts on this subject based on the ideXlab platform.
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Deformation Characteristic and prediction of flow stress for as cast 21cr economical duplex stainless steel under hot compression
Materials & Design, 2013Co-Authors: Dening Zou, Ying Han, Wei Zhang, Bao Cheng, Guanjun QiaoAbstract:Abstract Hot compression tests in the temperature range from 1273 to 1423 K and strain rate range from 0.01 to 10 s–1 were carried out on a Gleeble 1500D thermo-mechanical simulator for as-cast 21Cr economical duplex stainless steel (EDSS). The Deformation behavior and microstructural evolution were investigated. It is found that the flow behavior strongly depends on the strain rate and Deformation temperature, and the flow stress increases with the increase of strain rate and the decrease of temperature. The softening degree of ferrite becomes larger with decreasing strain rate and increasing Deformation temperature, and the austenite is gradually spheroidizing. The flow localization band easily happens at high strain rate and low temperature because of the uneven Deformation in the microstructure. Moreover, the constitutive model with the compensation of strain was developed on the basis of hyperbolic sine equation to predict the flow stress of as-cast 21Cr EDSS. The material constant in the model such as α, n, Q and ln A was functioned with the strain by sixth order polynomial. The results show that the developed constitutive model has excellent predictability of flow stress under the experimental Deformation conditions for as-cast 21Cr EDSS.
Seunghoon Nahm - One of the best experts on this subject based on the ideXlab platform.
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multiaxial Deformation Characteristic of a zr based bulk metallic glass variations of the plastic constraint factor underneath a spherical indenter
Journal of Materials Research, 2007Co-Authors: Yunhee Lee, Juyoung Kim, Unbong Baek, Seunghoon NahmAbstract:Multiaxial Deformation of Zr 55 Al 10 Ni 5 Cu 30 metallic glass was investigated by instrumented indentation tests with a spherical indenter. Contrary to the elastic–rigid-plastic behavior of bulk metallic glasses (BMGs), indentation pressure showed a significant increase with increasing indentation strain, and it was ascribed to a rapid transition of the plastic constraint factor (PCF). However, it was impossible to measure the PCF values from the indentation pressures in the Zr-based BMG because information on uniaxial flow stress was insufficient due to the limited flow strain of 2.2%. Here we developed a PCF assessment method using a relative residual depth h f / h max , which was experimentally confirmed by adopting it to spherical indentations of a steel sample having well-known flow properties. Flow properties of the BMG were calculated using the new PCF assessment method, and the effects of the materials pileup and low strain indentations on PCF and flow properties were discussed.
Zhigang Song - One of the best experts on this subject based on the ideXlab platform.
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Hot Deformation Characteristic and processing map of superaustenitic stainless steel S32654
Materials Science and Engineering: A, 2014Co-Authors: Wenjie Zheng, Jinzhong Xiang, Zhigang SongAbstract:Abstract The hot Deformation behavior of superaustenitic stainless steel S32654 was studied in the temperature range of 950–1200 °C and strain rate range of 0.001–10 s −1 employing hot compression tests. The results show that peak stress increases with decreasing of temperature and increasing of strain rate. The apparent activation energy of this alloy is about 469 kJ/mol. The processing maps for hot working were developed on the basis of flow stress data and the dynamic materials model. It is found that the features of the maps obtained in the strain range of 0.2–1.0 are fundamentally similar, indicating that the strain does not have a significant influence on processing map. The maps exhibited two domains. The first domain occurs in the strain rate range of 0.01–0.4 s −1 and temperature range of 1030–1150 °C with a peak efficiency of about 49%, which is considered as the optimum window for hot working. The microstructure observations of the specimens deformed in this domain showed the full dynamic recrystallization (DRX) structure with finer and more homogeneous grain sizes. The second domain occurs at the temperatures higher than 1160 °C and strain rates lower than 0.1 s −1 with a peak efficiency of about 41%, the microstructure observations in this domain also indicated the typical DRX structure accompanied with grain growth. A instability domain occurs at temperatures below 1175 °C and strain rate above 0.1 s −1 .
Dening Zou - One of the best experts on this subject based on the ideXlab platform.
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Deformation Characteristic and prediction of flow stress for as cast 21cr economical duplex stainless steel under hot compression
Materials & Design, 2013Co-Authors: Dening Zou, Ying Han, Wei Zhang, Bao Cheng, Guanjun QiaoAbstract:Abstract Hot compression tests in the temperature range from 1273 to 1423 K and strain rate range from 0.01 to 10 s–1 were carried out on a Gleeble 1500D thermo-mechanical simulator for as-cast 21Cr economical duplex stainless steel (EDSS). The Deformation behavior and microstructural evolution were investigated. It is found that the flow behavior strongly depends on the strain rate and Deformation temperature, and the flow stress increases with the increase of strain rate and the decrease of temperature. The softening degree of ferrite becomes larger with decreasing strain rate and increasing Deformation temperature, and the austenite is gradually spheroidizing. The flow localization band easily happens at high strain rate and low temperature because of the uneven Deformation in the microstructure. Moreover, the constitutive model with the compensation of strain was developed on the basis of hyperbolic sine equation to predict the flow stress of as-cast 21Cr EDSS. The material constant in the model such as α, n, Q and ln A was functioned with the strain by sixth order polynomial. The results show that the developed constitutive model has excellent predictability of flow stress under the experimental Deformation conditions for as-cast 21Cr EDSS.
Pengfei Guo - One of the best experts on this subject based on the ideXlab platform.
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research on Deformation Characteristic and stability control of surrounding rock during gob side entry retaining
Geotechnical and Geological Engineering, 2020Co-Authors: Pengfei Guo, Xiaohu Zhang, Yanyan Peng, Dingjie SunAbstract:In order to reveal the Deformation Characteristic of surrounding rock in gob-side entry retaining formed automatically, this paper compares the Deformation, damage and stress distribution Characteristics of surrounding rock in gob-side entry under two conditions of roof cutting or not. The influence of roof cutting on the Deformation and stress distribution of the rock surrounding roadway are revealed. The length of roof suspension is the main factor on stress distribution and Deformation of surrounding rock. With the decrease of roof length during gob-side entry retaining, the mining stress and the intensity of stress concentration of the coal wall in the gob-side entry are significantly reduced. It is proved that the partial stress transfer path between the roof of goaf and the roadway roof is cut off by roof cutting, so the influence of the mining stress on the gob-side entry is obviously weakened. The stress is transferred to the deep part of the coal wall for roof cutting. The field test shows that the roof-to floor convergence in the roof-cutting area is reduced by 46.2% compared with non roof cut area, and the sides convergence in the roof cut area is reduced by 52.6%. The research in this paper provides a solid theoretical and practical basis for the wide population and application of this technology in mines with similar conditions.