共查询到20条相似文献,搜索用时 625 毫秒
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以热模拟压缩实验为基础,研究了变形工艺参数(包括变形温度、应变速率和变形程度)对半固态Al-4Cu-Mg合金变形力学行为和微观组织的影响.研究结果表明:半固态Al-4Cu-Mg合金的流变应力峰值对变形温度和应变速率的变化比较敏感;变形温度和应变速率对稳态流动应力影响较小.应变速率对流变应力峰值的影响与变形温度有关.变形工艺参数对微观组织的影响为:随着变形温度的升高和应变速率的减小,α相晶粒平均尺寸增大,半固态Al-4Cu-Mg合金变形后的组织仍保持近球状组织,这与变形过程中固态α相的流动方式有关. 相似文献
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高应变速率及低温对工业纯钛力学性能的影响 总被引:1,自引:0,他引:1
探讨了高应变速率(动态)和低温对工业纯钛TA2拉伸力学性能的影响.结果表明:高应变速率和低温对TA2力学性能有影响.室温下,低应变速率1.6×10-3 s-1下,随应变速率增加,抗拉强度变化不大,随后略有增加,在8.0×102~1.2×103 s-1的高应变速率下,强度下降(约14%),塑性开始略有下降,随后得到恢复,未发生脆化现象.常规应变速率下,在室温至-196℃温度范围内,随温度降低,强度大幅增加,在-196℃时,强度增加约50%,而塑性先略有下降,随后上升;-196℃时,升至40%,增加约48%,有增塑现象;但当较高应变速率和低温共同作用时,TA2发生脆化,塑性明显下降而强度增加.TA2在高应变速率、低温条件下独特的力学性能是与孪生和滑移变形机制是否启动有关. 相似文献
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超高强度钢热变形方程 总被引:3,自引:1,他引:2
热冲压成形工艺是将冲压成形工艺和淬火工艺集成在同一工序中进行的新型成形工艺。根据热冲压工艺的时间-温度特征,采用Gleeble3800热模拟系统,在温度600℃~900℃、应变速率0.01/s~0.5/s下,对热冲压钢板USIBOR1500进行热拉伸实验,获得了相应的应力-应变曲线。结果表明,USIBOR1500钢的热变形行为符合应变硬化加动态回复机制,变形温度和应变速率对其力学性能有很大的影响;计算了USIBOR1500钢的热变形激活能,并通过对变形激活能及Zener-Hollomon参数的研究,建立了超高强度硼钢热变形稳态流变应力模型和热变形方程,为估算成形时所需的最大载荷及设备选取提供参考。 相似文献
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AZ80合金高温变形行为及加工图 总被引:6,自引:0,他引:6
为实现AZ80合金塑性成形的数值模拟和制定其合理的热加工工艺,利用热模拟机对AZ80合金进行不同变形温度和应变速率的高温压缩变形行为研究.结果表明:AZ80合金的高温流动应力-应变曲线主要以动态回复和动态再结晶软化机制为特征,峰值应力随变形温度的降低或应变速率的升高而增加;在真应力-应变曲线基础上,建立的AZ80合金高温变形的本构模型较好地表征其高温流变特性,模型计算精度高;同时,利用建立的AZ80合金的DMM加工图分析其变形机制和失稳机制,从提高零件力学性能角度考虑,可以优先选择变形温度为300~350 ℃、应变速率为0.001~0.01 s-1的工艺参数. 相似文献
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工艺参数对液态模锻6082合金组织及力学性能的影响 总被引:1,自引:0,他引:1
鉴于变形铝合金6082的结晶温度间隔较宽,铸造成形条件性能较差;而原热模锻工艺成形性能较好,但成本高、设备吨位大.本文讨论了不同的工艺参数条件对通过液态模锻工艺得到的6082合金试验件的组织和力学性能的影响.结果表明,其平均力学性能达到或接近原热锻件的性能,比金属型铸造件力学性能要好,且组织细化.其中,施加125 MPa的压力时,组织敛密,抗拉强度、塑性和硬度值最高;合金浇注温度在660℃时,抗拉强度值最高,而塑性和硬度在680℃时最佳;保压时间受多种因素的影响,随着保压时间的延长,力学性能呈下降的趋势. 相似文献
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应变速率对低C高Mn TRIP/TWIP钢组织演变和力学行为的影响 总被引:1,自引:0,他引:1
研究了Fe-18Mn低C高Mn TRIP/TWIP钢在应变速率范围为1.67×10-4-103s-1的室温拉伸实验过程中力学性能和组织的变化.在准静态拉伸应变速率范围内(1.67×10-4-1.67×10-1s-1),应变速率对高Mn TRIP/TWIP钢的抗拉强度产生逆效应,随着应变速率的加快,抗拉强度和延伸率都降低;而在动态拉伸应变速率范围内(101-103s-1),应变速率对高Mn TRIP/TWIP钢的延伸率产生逆效应,抗拉强度和延伸率都随着应变速率的加快而增加;在应变速率为103s-1时,高Mn TRIP/TWIP钢抗拉强度可达到957 MPa,延伸率达到55.8%,具有较好的综合力学性能;随着应变速率的提高,马氏体转变量减少,孪生变形向多个方向发展.采用SEM,TEM和XRD等方法对变形前后的组织进行了分析,在所有应变速率范围内的拉伸变形过程中都产生了奥氏体向马氏体转变和形变孪晶,并且在应变速率为103s-1的高速拉伸过程中产生绝热温升效应,使得基体软化. 相似文献
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在变形温度1100 ℃,变形量30%的条件下进行平面应变压缩,并对压缩后的06Cr19Ni9NbN钢进行微观组织观察及力学性能测试。将压缩后试样进行1050 ℃保温2 h 的固溶处理,观察固溶处理后试样微观组织及力学性能的变化。结果表明:热压缩过程中,变形量越大的区域发生动态再结晶的程度越高,晶粒尺寸越小,组织越均匀。固溶处理后,细小的再结晶晶粒逐渐长大,组织变得较为均匀,晶粒尺寸增加到100 μm后逐渐趋于稳定。固溶处理对该钢的伸长率影响不大,但固溶处理后其屈服强度降低约20 MPa。 相似文献
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Plastic deformation and dynamic recrystallization (DRX) behaviors of magnesium alloy AZ31B during thermal compression and extrusion processes were studied.In addition, effects of deformation temperature and rates on the microstructure and mechanical properties were investigated.The results show that the DRX grains nucleate initially at the primary grain boundaries and the twin boundaries, and the twinning plays an important role in the grain refinement.The DRX grain size depends on the deformation temperature and strain rate The average grain size is only 1 μm when the strain rate is 5 s-1 and temperature is 250 ℃.It is also found that the DRX grain can grow up quickly at the elevated temperature.The microstructure of extruded rods was consisted of tiny equal-axis DRX grains and some elongated grains.The rods extruded slowly have tiny grains and exhibit good mechanical properties. 相似文献
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T. Ungár I. Alexandrov M. Zehetbauer 《JOM Journal of the Minerals, Metals and Materials Society》2000,52(4):34-36
The microstructures of ultrafine-grained nanostructured materials developed by severe plastic deformation are widely varied in their grain size and grain-size distribution; grain boundaries and their structures; lattice defects, especially dislocations; point defects; and impurities. All of these features can be influenced by the way severe plastic deformation is applied, and thereby have decisive effects on the physical and mechanical properties of the material. Probably, the most important factors determining microstructure are the imposed stress tensor, the degree and rate of strain, the temperature of deformation, the chemical composition of the deformed material, and the type of crystal lattice, showing that in order to develop specific properties, it is crucial to understand and optimize the microstructure. 相似文献
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深入分析了各变形工艺参数对TB8合金固溶处理显微组织的影响规律,建立了固溶组织再结晶体积分数、平均晶粒尺寸与变形工艺参数间的神经网络预测模型。结果表明,冷却和热处理制度相同的条件下,变形温度、变形程度和应变速率等变形工艺参数对TB8钛合金形变且固溶处理后的显微组织有重要的影响,若想获得晶粒较为细小且均匀的组织,需要在合适的应变速率下适当提高变形程度和降低变形温度;人工神经网络的预测结果与实测结果的高度拟合,表明人工神经网络模型可以较为精确地预测TB8合金的显微组织随变形工艺参数的变化而变化的情况。以上研究工作为TB8合金热加工工艺的制定提供了更为科学的理论依据。 相似文献
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The influences of deformation temperature and deformation degree on the microstructure and mechanical properties of AZ80 magnesium alloy were investigated by the adoption of isothermal plain strain compression experiment.The results show that thermal compression processing can refine the grain size and the tensile strength of all the deformed AZ80 magnesium alloys is increased to the maximum of 320 MPa.With the increasing of deformation temperature,the tensile strength decreases;with the increasing of th... 相似文献
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采用热模拟试验机对轧制态6082-T6铝合金进行热压缩试验,分析了合金在变形温度100~400 ℃,应变速率0.01 s-1条件下的流变应力,对不同温度热变形的微观组织进行了表征。结果表明,轧制态6082铝合金的力学性能受变形温度和轧制方向的影响。变形过程中应力呈现负的温度敏感性,即随着变形温度升高,应力不断下降。合金表现出明显的力学性能各向异性,压缩强度在与轧制方向呈0°和90°较高,45°方向强度较低。经过热压缩变形后,与轧向呈不同方向的6082-T6铝合金的晶粒组织均沿着剪切力方向发生扭曲,同时,变形温度对晶粒组织的演变影响不大。随着变形温度的升高,合金基体内的位错密度明显下降,析出相发生粗化。 相似文献
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Ying Zhao Baoyun Song Jiuyang Pei Chunbo Jia Bing Li Guo Linlin 《Journal of Materials Processing Technology》2013,213(11):1855-1863
Experiments and numerical simulations were conducted to analyze the continuous extrusion of AA6063 aluminum alloy under extrusion wheel angular velocities of 0.52, 0.78, 1.04 and 1.3 rad/s. Simulation results indicate that variations in extrusion wheel velocity directly affect material deformation and significantly influence the maximum extrusion temperature. This work also reveals that deformation and temperature have opposing effects on the microstructure of the resulting product. A greater wheel velocity causes a higher strain rate and extrusion temperature. Increasing the wheel velocity, at an initially low speed, causes a large increase in strain rate. This results in a decrease in grain size. In contrast, at high wheel velocities, further increases to wheel velocity have much less effect on the strain rate, leading to an increase in grain size as the increased extrusion temperature dominates the mechanics of grain growth. Tensile test results demonstrate that the tensile strength of the resulting aluminum extrusions mainly depends on the exit temperature, which is decided by the deformation speed. Tensile strength and hardness slightly increase with increased deformation speed. Extremely high extrusion temperature results in brittle failure and low mechanical properties of the resulting product when the extrusion speed reaches 1.3 rad/s. This paper suggests that an optimum extrusion wheel velocity, which will generate products with good mechanical properties, exists. 相似文献
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TC4钛合金高温变形时的微观组织演变 总被引:2,自引:0,他引:2
基于TC4钛合金压缩变形时的微观组织观察和定量金相实验,研究了变形工艺参数(变形温度、应变速率和变形程度)对微观组织演变和组织参数(初生α相晶粒尺寸和体积分数)的影响。结果表明: 在α+β两相区,随着变形温度的升高,初生α相晶粒尺寸呈波浪状变化,初生α相逐渐减少;随着应变速率的增加,初生α相形貌由等轴状转变为长条状,微观组织参数的变化规律与温度有关,当变形温度高于1203 K时,初生α相晶粒尺寸逐渐减小,而低于1203 K时,初生α相晶粒尺寸呈波浪状变化。当变形温度高于1223 K时,初生α相体积分数呈波浪状变化,而低于1223 K时,初生α相体积分数逐渐减小;随着变形程度的增加,二次α相逐渐减少,初生α相晶粒尺寸呈先减小后略有增大的趋势,而初生α相体积分数变化较小 相似文献