共查询到20条相似文献,搜索用时 15 毫秒
1.
随着工业技术的发展和能源问题的突出,铝合金以其质量轻、耐腐蚀性能好、成形性能和加工性能良好等优势成为轻型化首选的材料类型之一。以5A02铝合金冷轧板材为研究对象,通过单向拉伸试验和金相试验对不同变形温度、应变速率条件下5A02铝合金的塑性性能进行分析,并且借助试验数据和Zener-Hollomo参数模型,对高温条件下5A02铝合金的本构模型进行研究。研究结果表明:5A02铝合金在高温条件下变形时,应变速率和变形温度对延伸率的影响很大。在应变速率为0.01s-1、0.001 s-1、0.0005 s-1和0.0001 s-1条件下,当变形温度大于250℃时,5A02铝合金的延伸率大于100%。当变形温度为150℃~250℃时,5A02铝合金的真实应力-应变曲线属于动态回复型,而当变形温度大于250℃时,流变应力曲线存在明显的软化现象。 相似文献
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In order to determine the optimum hot-forming processing parameters for 6063 aluminum alloy, the compressive deformation behavior of 6063 aluminum alloy was investigated at the temperatures from 300 to 500?°C and strain rates from 0.5 to 50?s?1 on a Gleeble-1500 Thermal Simulator. Based on the compression experimental data, a novel adaptive network-based fuzzy inference system (ANFIS) model is developed to predict the flow behavior of 6063 aluminum alloy. In the ANFIS system, the inputs of the ANFIS are the strain, the strain rate and the temperature, whereas the flow stress is the output. The effects of strain, strain rate, and temperature on the flow behavior of 6063 aluminum alloy have been studied by comparing the experimental and the predicted results using the developed ANFIS model. The results show that predicted values using the developed model are in good agreement with the experimental data, which demonstrates the reliability of the developed ANFIS model. 相似文献
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The flow stress behavior of aluminum alloy 6A10 was studied by the hot compression tests at temperatures from 350 °C to 550 °C and strain rates from 0.1 s?1 to 10 s?1 with Gleeble-1500 thermo-mechanical simulator. The result demonstrates that the temperatures of specimen differ from initial ones affected by deformation conditions, and that the softening mechanism is dynamic recovery. A new approach was proposed to analyze the flow stress character directly from actual stress, strain, temperature and strain rate data, without performing any previous flow stress correction caused by temperature variation. Comparisons between the experimental and predicted results confirm that the established flow stress model can give reasonable estimation, indicating that the mentioned approach can be used in flow stress model analysis of the materials that undergo only dynamic recovery based on the data obtained under variable deformation temperature. 相似文献
5.
通过热压缩实验研究了ZL270LF铝合金在变形量为70%,温度为300~550 ℃,应变速率为 0.01~10 s-1范围的热变形行为,建立了流变应力本构方程模型,绘制出了二维热加工图,确定了最佳热加工区域,采用电子背散射衍射(EBSD)和透射电子显微镜(TEM)技术研究了该合金的组织演变规律。结果表明:ZL270LF铝合金的流变应力随变形温度的升高和应变速率的降低而降低,热变形激活能为309.05 kJ/mol,最优热加工区为温度470~530 ℃、应变速率为0.01~1 s-1。该合金在热变形过程中存在3种不同的DRX机制,即连续动态再结晶(CDRX)、不连续动态再结晶(DDRX)和几何动态再结晶(GDRX),其中CDRX是ZL270LF铝合金动态再结晶的主要机制。 相似文献
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研究ZK60合金的高温流变应力行为。分别采用Kocks-Mecking模型和Avrami方程对合金的应变强化和动态再结晶过程进行模拟,在此基础上,构建一个考虑合金动态再结晶软化的流变应力方程并对流变应力进行预测。结果表明:预测曲线与实验结果具有很高的相关系数,所构建的流变应力方程能准确地描述热变形过程中合金的流变应力行为。微观组织观察表明在变形初期合金组织主要为动态回复组织,随着应变增加,逐渐转变为再结晶组织。 相似文献
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Hot plane strain compression tests of 6013 aluminum alloy were conducted at temperatures ranging from 613 to 773 K and strain rates ranging from 10-3 to 10 s-1. A novel model is developed to describe the temperature rise considering deformation heating integrated with heat transfer in tests. The experimental flow stress data are corrected by the proposed novel model. Based on the corrected flow stress, the modified power function constitutive model is developed considering the coupled effects of deformation temperature and strain rate on flow stress. Meanwhile, another two widely used models, temperature-compensated power function and straincompensated hyperbolic sine constitutive model, are also established for the studied 6013 aluminum alloy. Finally, the three constitutive models are compared from the aspects of accuracy, stability and efficiency. It is found that the experimental flow stress is significantly affected by the temperature rise. Furthermore, the influence of heat transfer on temperature rise cannot be ignored. When the constitutive model is established, the coupled effects of deformation temperature and strain rate on flow stress should be considered. The modified power function constitutive model is the best one in describing the flow behavior among the three models. 相似文献
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采用Gleeble-3800热模拟机对TB15钛合金进行等温恒应变速率热压缩试验,研究其在变形温度为810~930℃、应变速率为0.001~10s-1和高度压下量为60%条件下的热变形行为;建立了物理、支持向量回归(SVR)和响应面三种本构关系模型来预测TB15钛合金的流动应力,同时对比了三种本构模型的预测精度。结果表明:TB15钛合金的流动应力随应变速率的降低和变形温度的升高而减小,峰值应力的变化对应变速率的敏感性更高;物理本构模型、SVR本构模型和响应面本构模型相关系数R均大于0.98,但是响应面本构模型的R值达到了0.993,而且响应面本构模型的相对误差在±5%范围内的预测值频率达到了67.9%,大于物理本构模型的58.6%。同时经过方差分析得到所构建的响应面本构模型的显著性检验值P<0.0001,表明响应面本构模型预测的流动应力与变形温度、应变速率和应变之间的回归关系显著,比物理本构模型和SVR本构模型有更高的精度,能够更好的预测TB15钛合金的流动应力。 相似文献
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基于应变影响的7A09铝合金等温压缩流动应力模型 总被引:1,自引:0,他引:1
在Gleeble-1500型热模拟压缩机上研究7A09铝合金在温度为633~733 K、应变速率为0.01~10.0s-1、最大变形程度为60%条件下的高温流动行为;基于7A09铝合金高温压缩时的流动应力特征,建立反映应变影响的7A09铝合金流动应力模型.结果表明:随着变形温度的升高和应变速率的降低,合金的流动应力显著降低;当应变超过一定值后,随着应变的增加,高、低应变速率下合金的流动应力变化趋势不同;建立的流动应力模型的计算值与实验值之间的最大误差为7.77%,平均误差为2.69%;与不考虑应变影响的流动应力模型相比,该模型的拟合精度高,能较好地描述7A09铝合金高温变形过程中的流动行为,为铝合金高温变形过程的数值模拟奠定了较好的基础. 相似文献
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通过20MnNiMo钢多组试样的热压缩实验获得应变速率为0.01~10 s-1、变形温度为1173~1473 K条件下的真应力-应变数据。结合Arrhenius双曲正弦本构方程,通过线性回归分析求解得到不同变形条件下本构模型中的热变形激活能Q,材料常数n、α及结构因子A,从而构建了用于表征20MnNiMo钢流变应力与应变量、温度、应变速率之间内在关系的本构方程。研究结果表明:20MnNiMo钢在热压缩变形过程中发生了明显的动态软化行为,流变应力水平随应变速率的增加而增加,随温度的升高而降低;流变应力的预测值与实验值较吻合,而且预测的最大相对误差仅为7.54%。 相似文献
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Yajing Yang Fuguo Li Zhanwei Yuan Huijuan Qiao 《Journal of Materials Engineering and Performance》2013,22(9):2641-2655
In this paper, the constitutive relationship of an aluminum alloy reinforced by silicon carbide particles is investigated using a new method of double multivariate nonlinear regression (DMNR) in which the strain, strain rate, deformation temperature, and the interaction effect among the strain, strain rate, and deformation temperature are considered. The experimental true stress-strain data were obtained by isothermal hot compression tests on a Gleeble-3500 thermo-mechanical simulator in the temperature range of 623-773 K and the strain rate range of 0.001-10 s?1. The experiments showed that the material-softening behavior changed with the strain rate, and it changed from dynamic recovery to dynamic recrystallization with an increase in the strain rate. A new constitutive equation has been established by the DMNR; the correlation coefficient (R) and average absolute relative error (AARE) of this model are 0.98 and 7.8%, respectively. To improve the accuracy of the model, separate constitutive relationships were obtained according to the softening behavior. At strain rates of 0.001, 0.01, 0.1, and 1 s?1, the R and AARE are 0.9865 and 6.0%, respectively; at strain rates of 5 and 10 s?1, the R and AARE are 0.9860 and 3.0%, respectively. The DMNR gives an accurate and precise evaluation of the flow stress for the aluminum alloy reinforced by silicon carbide particles. 相似文献
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Lin Hua Fanzhi Meng Yanli Song Jianing Liu Xunpeng Qin Lianbing Suo 《Journal of Materials Engineering and Performance》2014,23(3):1107-1113
As main light-weight material, aluminum alloy sheets have been widely applied to produce auto body panels. In order to predict the formability and springback of aluminum alloy sheets, a precise constitutive model is a necessity. In this article, a series of warm tensile tests were conducted on Gleeble-1500D thermal mechanical simulator for 6111-T4 aluminum alloy sheets. The corresponding strain rate ranged from 0.015 to 1.5 s?1, and the temperature ranged from 25 to 350 °C. The relationship between the temperature, the strain rate, and the flow stress were discussed. A constitutive model based on the updated Fields-Backofen equation was established to describe the flow behavior of 6111-T4 aluminum alloy during the warm tensile tests. Subsequently, the average absolute relative error (AARE) was introduced to verify the predictability of the constitutive model. The value of AARE at the uniform plastic deformation stage was calculated to be 1.677%, which demonstrates that the predicted flow stress values were in accordance with the experimental ones. The constitutive model was validated by the fact that the simulated results of the warm tensile tests coincided with the experimental ones. 相似文献
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LUO Jiao LI Miaoquan School of Materials Science Engineering Northwestern Polytechnical University Xi’an China 《稀有金属(英文版)》2011,30(6):555-564
Isothermal compression of Ti-6Al-4V alloy was conducted in the deformation temperature range of 1093-1303 K,the strain rates of 0.001,0.01,0.1,1.0,and 10.0 s-1,and the height reductions of 20%-60% with an interval of 10%.After compression,the effect of the processing parameters including deformation temperature,strain rate,and height reduction on the flow stress and the microstructure was investigated.The grain size of primary α phase was measured using an OLYMPUS PMG3 microscope with the quantitative metallography SISC IAS V8.0 image analysis software.A model of grain size in isothermal compression of Ti-6Al-4V alloy was developed using fuzzy neural net-work(FNN) with back-propagation(BP) learning algorithm.The maximum difference and the average difference between the predicted and the experimental grain sizes of primary α phase are 13.31% and 7.62% for the sampled data,and 16.48% and 6.97% for the non-sampled data,respectively.It can be concluded that the present model with high prediction precision can be used to predict the grain size in isothermal compression of Ti-6Al-4V alloy. 相似文献
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采用Gleeble-1500热模拟机,研究了基于半固态等温热处理技术制备的Y112铝合金,在不同变形温度和变形速率下的半固态压缩变形力学行为。结果表明,当压缩应变低于0.8时,随着压缩应变的增加,合金的半固态压缩应力首先快速增加,然后快速减小,最后逐渐保持不变;同时,在不同变形温度和变形条件下,合金在压缩应变近似为0.07时均可获得最大的半固态压缩应力;此外,随着变形温度降低或变形速率升高,合金的半固态压缩变形应力增加。 相似文献
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在温度623~773 K和应变速率0.01~1 s-1条件下,采用等温压缩试验研究析出硬化AA7022-T6铝合金的热力学行为。结果表明,动态再结晶是主要的热变形机制,特别是在高温和低应变速率下。采用改进的JohnsonCook (J-C)模型和应变补偿Arrhenius模型预测不同变形条件下的热流变行为。这两种模型的线性相关系数分别为0.9914和0.9972,平均相对误差(ARE)分别为6.074%和4.465%,均方根误差(RMSE)分别为10.611和1.665 MPa。结果表明,应变补偿Arrhenius模型能准确预测AA7022-T6铝合金的热流变应力。 相似文献
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Superplastic behavior of powder-metallurgy (PM) processed 7475 +0.7Zr Al alloy having a fine grain size of 2 um was investigated.
Strain-rate-change tests were conducted at elevated temperatures to examine the strain rate-stress relations. The deformation
behavior was analyzed by assuming the presence of threshold stress for grain boundary sliding. After the threshold-stress
compensation, the plastic flow was found to correlated well with lattice self-diffusion in pure aluminum. A maximum tensile
elongation of up to 1000% was observed at a very high strain rate near l0-1s-1 and 515°C. A deformation map was constructed to identify the dominant deformation mechanism for the PM alloy. It was the
grain boundary sliding controlled by lattice diffusion in aluminum. Evidence of short fiber or whisker-like formation were
observed on the fractured samples over a wide range of temperature. 相似文献
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Wenduan Yan Gaosheng Fu Hongling Chen Guiqing Chen 《Journal of Materials Engineering and Performance》2012,21(10):2203-2206
Flow stress characteristic of 1235 aluminum alloy treated by different purification methods was studied by dynamic thermo-simulation test. The effects of oxide inclusions on steady flow stress, peak stress, and true strain corresponding to peak stress were also examined in this study. The results showed that there is a steady flow feature in 1235 aluminum alloy during hot compression deformation. 1235 aluminum alloy with lower inclusion content shows higher strength, therefore, the plasticity and toughness are better and improve the hot-working character of the alloy. Therefore, reducing inclusion content is effective for improving the hot deformation character of aluminum foil (1235 aluminum alloy). 相似文献
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A Flow Stress Model for AZ61 Magnesium Alloy 总被引:9,自引:0,他引:9
H.T.Zhou X.Q.Zeng Q.DWang W.J.Ding 《金属学报(英文版)》2004,17(2):155-160
The flow stress behaviors of AZ61 alloy has been investigated at temperature range from 523 to 67314 with the strain rates of 0.001-1s^-1.It is found that the average activation energy, strain rate sensitive exponent and stress exponent are different at various deformation conditions changing from 143.6 to 176.3kJ/mol,0.125 to 0.167 and 6 to 8 respectively. A flow stress model for AZ61 alloy is derived by analyzing the stress data based on hot compression test.It is demonstrated that the flow stress model including strain hardening exponent and strain softening exponent is suitable to predicate the flow stress. The prediction of the flow stress of AZ61 alloy has shown to be good agreement with the test data.The maximum differences of the peak stresses calculated by the model and obtained by experiment is less than 8%. 相似文献
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WEI Yanguang XIONG Baiqing ZHANG Yong’an LIU Hongwei ZHU Baohong and WANG feng State Key Laboratory for Fabrication & Processing of Non-ferrous Metals Beijing General Research Institute for Non-ferrous Metals Beijing China 《稀有金属(英文版)》2006,25(6):665-670
1. Introduction New spray formed 70Si30Al alloy developed for electronic packaging application has excellent physical characteristics [1-5], which include low coefficiency of thermal expansion (6.8 × 10?6/K), high thermal conductivity (120 W/(m?K)), and low density (2.4 g/cm3), therefore, the exploitation and application of the alloy have an extensive prospect. To evaluate the deformation characteristics of spray formed 70Si30Al and to determine the appropriate hot deformation procedure of … 相似文献