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以25Cr2Ni4MoV钢大锻件的镦粗与拔长过程为研究对象,采用圆柱体单轴压缩试验得到了材料的真实应力-真实应变曲线,构建了材料的高温流变应力模型和加工图,并基于弹塑性有限元法建立了用于镦粗与拔长过程分析的有限元模型。通过对镦粗和拔长过程的数值仿真分析,获取了不同工艺条件下锻件内部典型节点的温度、应变和应变速率的工艺参数变化,确定了典型节点在加工图中的工艺参数位置,分析了镦粗和拔长过程的工艺稳定性,确定了合理的开坯锻造工艺。结果表明,镦粗过程采用1200℃的初始温度、50 mm·s-1的压下速率,拔长过程采用方案2(3道次拔长+摔圆)有利于改善工件变形后的温度和变形均匀性,获得更大的耗散值,进而改善锻件组织,使材料表现出较好的塑性加工能力。 相似文献
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本文用常温云纹法与数值模拟法研究了筒体锻件整体镦粗与局部镦粗工艺的变形规律,得到了整体镦粗工艺的坯料尺寸图。对于在端部内壁处取样的核电筒体锻件,应采用局部镦粗工艺,以锻透取样部位。为避免端部折叠,局部镦粗时单砧压下量应小于10%。 相似文献
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火车车轮成形工艺研究及有限元模拟 总被引:8,自引:2,他引:8
介绍了火车车轮的成形工艺。采用有限元模拟了车轮成形工艺的镦粗和预成形工步,得出变形过程中材料的流动规律、工件内部的应变场和温度场等信息。通过多次模拟镦粗压下量对预成形的影响,确定了最佳的镦粗压下量。这些信息为变形过程的控制提供了理论依据。 相似文献
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A constitutive equation was proposed to describe the effect of grain size on the deformation behavior. And a coupling simulation of deformation with heat transfer and microstructure was carried out in isothermal upsetting process of Ti60 alloy. The effects of processing parameters on the equivalent strain, the equivalent stress, the temperature rise and the grain size distribution in isothermal upsetting process of Ti60 alloy were analyzed. It is concluded that the uniformity of equivalent strain and equivalent stress increases with the increase of deformation temperature. However, the temperature rise and the grain size decreases with the increase of deformation temperature. The non-uniformity of equivalent strain, equivalent stress, temperature field and grain size increases with the increase of height reduction. And the calculated grain size using simulation is in good agreement with the experimental one. 相似文献
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为提高六角头螺栓头部热镦成形工序的合格率,选取影响成形质量较大的加热温度、热镦速度、摩擦系数3个因素设计了正交试验,并利用有限元分析软件Deform-3D建立了热镦过程的热力耦合数值模型,用数值模拟的方法对热镦后坯料的等效应力、等效应变、损伤值和成形载荷这4个目标参数进行多目标优化分析,优化设计了A286高温合金六角头螺栓头部热镦成形的工艺参数。数值模拟结果表明:与厂家原有方案相比,当工艺参数优化为加热温度为1050℃、热镦速度为60 mm·s-1、摩擦系数为0.3时,各目标参数均有所改善,可大大提高工件的合格率及生产效率。采用经优化的热镦工艺参数组合进行生产试验,结果显示:螺栓头部成形效果好,满足该工序质量要求。本研究为实际生产提供了理论依据。 相似文献
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Dashan Sui Lingling Zhu Tao Wang Peipei Zhang Zhenshan Cui 《JOM Journal of the Minerals, Metals and Materials Society》2017,69(10):1773-1778
Forging experiments were designed and carried out on a 3150 kN hydraulic press to investigate the effects of different processes on the microstructure evolution for 316LN steel. The forging processes included single-pass (upsetting) and multipass (stretching) deformations, and the experimental results indicated that the average grain size varied with forging processes. Moreover, the size had distinct differences at different positions in the workpiece. Meanwhile, numerical simulations were implemented to study the influence of temperature, strain, and strain rate on microstructure evolution. The results of experiments and simulations comprehensively demonstrated that dynamic, static, and meta-dynamic recrystallization could coexist in the hot forging process and that the recrystallization process could easily occur under the conditions of higher temperature, larger strain, and higher strain rate. Moreover, the temperature had more significant influence on both recrystallization and grain growth. A higher temperature could not only promote the recrystallization but also speed up the grain growth. Therefore, a lower temperature is beneficial to obtain refinement grains on the premise that the recrystallization can occur completely. 相似文献
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针对车用扭杆端头在镦粗加工时,其始锻温度、锻造方式以及锻机进给速度等工艺参数对端头的表面质量影响较大的问题,采用有限元法,建立车用扭杆及端头的有限元模型,利用Deform-3D软件对扭杆及其端头进行网格划分以及边界条件设置,对其镦粗过程进行仿真,考虑了热交换模型,对不同的始锻温度和进给速度下,扭杆端头所产生的轴向应力、轴向应变以及表面损伤进行探究,得出了适用于车用扭杆端头镦粗工艺的相关规律。结果表明:始锻温度在1150~1200℃之间、锻机进给速度为1 mm·s-1时,车用扭杆端头的表面损伤最小,工件性能较好。 相似文献
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The hot compression tests of 42CrMo steel were performed in the temperature range of 850–1150 °C at strain rates of 0.01–10 s?1 and deformation degrees of 10–60% on Gleeble-1500 thermo-simulation machine. The optical microstructures in the center region of the section plane were examined. Based on the results from thermo-simulation experiments and metallographic analysis, the dynamic recrystallization mathematical models of 42CrMo steel were derived. The effects of processing parameters, including the strain rate and deformation temperature, on the microstructure evolution of 42CrMo steel hot upsetting process were discussed by integrating the thermo-mechanical coupled finite element method with the derived microstructure evolution models. The fraction of dynamic recrystallization and dynamic recrystallization grain sizes during the hot upsetting process of 42CrMo steel were predicted. The results show that the effects of strain rates and deformation temperatures on the microstructure evolution of 42CrMo steel hot upsetting process are significant, and a good agreement between the predicted and experimental results was obtained, which confirmed that the derived dynamic recrystallization mathematical models can be successfully incorporated into the finite element model to predict the microstructure evolution of hot upsetting process for 42CrMo steel. 相似文献
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An investigation of a coupled analysis of a thermo-elastic-plastic model during warm upsetting 总被引:2,自引:0,他引:2
The primary purpose of this paper is to construct a thermo-elastic-plastic model which can be utilized in the simulation of a more realistic metal forming process under a warm forming condition. In this model flow stress is taken as a function of strain, strain rate and temperature. The finite element method and the finite difference method are adopted to simulate the whole forming process. The strain is taken by a Taylor's series expansion and is associated with its corresponding convergent criterion, an available scheme for the calculation of the strain rate is thus evolved. Furthermore, the strain rate and temperature effect during the warm upsetting process are also investigated. The temperature predicted in the proposed model for the upsetting process agrees quite well with Pohl's experimental data. 相似文献
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楔横轧大断面收缩率一次楔成形轧件心部质量规律及原因 总被引:2,自引:0,他引:2
为确定楔横轧大断面收缩率一次楔成形工艺心部质量的加工界限,对大断面收缩率下轧件心部质量规律进行了深入探索。采用实轧实验方法得到轧件心部最大孔洞面积数据;对比常规断面收缩率下轧件心部最大缺陷尺寸数据,得到大断面收缩率一次楔成形轧件的心部质量规律;并利用有限元数值模拟方法对大断面收缩率与常规断面收缩率轧件心部应力、应变进行对比分析,找出规律的原因。所得规律为,大断面收缩率轧制轧件心部质量整体好于常规断面收缩率轧制,另揭示出其原因为,大断面收缩率轧制轧件金属瞬时轴向流动量大,杆部中心剩余金属少,可供缺陷发展的空间也较小;不利于轧件心部质量的应力应变作用的时间较短,与工艺时间相同时刻常规断面收缩率的应力应变最大值相差比例也较小,静水压力在整个轧制过程中有利于轧件心部质量。 相似文献
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大型筒体件反复镦扩工艺的常温实验室模拟研究 总被引:1,自引:0,他引:1
参照实际核电压力壳(RPV)大型筒体镦件反复镦扩工艺,在常温下用金属铅材料设计成缩小比例尺寸的筒体试件,使用实验室300kN万能材料试验机缓慢加压变形.模拟研究了大型筒体件反复镦扩工序的变形规律,定量绘出了模拟变形试件中等效应变EI等值线分布图,总结出反复镦扩变形分区的典型特征,研究了反复镦扩次数对工艺变形效果的影响.研究结果,对实际大型筒体件生产有重要参考价值. 相似文献
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