共查询到20条相似文献,搜索用时 31 毫秒
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08F钢温锻温度范围内流动应力的实验研究与数学建模 总被引:1,自引:0,他引:1
本文通过热模拟实验 ,测定了 0 8F钢在温锻温度范围内的流动应力关系曲线 ,并对其变化规律进行系统分析 ;然后将所获得的实验数据应用于材料流动应力的数学建模 ,在修正、优化传统模型的基础上 ,提出了适用于低碳钢温锻的流动应力关系数学模型 ,该模型充分考虑了温度、等效应变、应变速率以及材料成分等因素给流动应力带来的影响 ;最后采用非线性回归的方法对该流动应力数学模型进行处理 ,建立起适用于 0 8F钢温锻的流动应力数学模型 ,并进行了计算验证 相似文献
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大锻件中心压实法(JTS)锻造过程有限元分析 总被引:3,自引:0,他引:3
在大锻件生产中,中心压实法(JTS法)是压实大锻件中心缺陷的一种有效方法.但在具体的工艺实施过程中,对大锻件在JTS法锻造中的温度梯度控制,钢锭外表面的冷却控制,以及温度梯度对内部的应力应变及组织的影响缺乏足够的认识,所以很难掌握其规律.大锻件单件生产的特点,又限制了其工艺实验的可行性.本文利用有限元方法,根据温度场的特点,建立合理的边界条件及参数,计算吹风和喷水等冷却方式所对应的锻件温度场.通过热力耦合模型和刚塑性有限元分析,模拟在内外具有较高温度梯度情况下的锻件应力应变场,分析了温度梯度对锻件内部应力应变的影响规律.结果表明,锻件的温度梯度对其应力应变具有重要影响,温度梯度越大,锻件中心的等效应变和静水压应力越大,压实中心缺陷的效果越好.该模拟结果及其参数将有助于制定合理的大锻件生产工艺. 相似文献
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This paper examines the efficiency and capability of Dynet, a recurrent neural network model for the prediction of the damage evolution during hot non-uniform, non-isothermal forging on the basis of a limited number of damage snapshots during the process. A Bayesian algorithm is introduced to optimise the hyperparameters related to the noise level and weight decay. In order to examine the capability of the model to capture the underlying trends when presented with sparse and noisy evidence, a synthetic relation between damage accumulation in a metal matrix composite and strain, strain rate and deformation temperature has been used to generate training data (evidence) of varying accuracy and sparseness. The results show that the Bayesian algorithm performs very well, and that no significant overfitting is observed. In addition, this algorithm not only gives the expectation value of damage level, but also an estimate of its uncertainty. 相似文献
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TC6合金等温锻造过程中晶粒尺寸的数值模拟 总被引:5,自引:2,他引:5
通过引入一个与微观组织相关的函数对稳态流动应力模型进行修正,建立了金属材料高温变形时的稳态流动应力模型.并将该耦合微观组织参数的流动应力模型写入有限元程序中,模拟了TC6合金叶片在等温锻造过程中初生α相晶粒尺寸的变化.研究了变形工艺参数(压下量,变形温度,变形速度和摩擦因子)对零件内部初生α相晶粒尺寸的影响. 相似文献
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通过热压缩试验研究钼金属在应变速率为0.01~10 s~(-1),变形温度为900~1450 ℃条件下的热变形性能,建立了基于流变应力的钼金属热变形的本构方程.应用有限元分析软件DEFORM中的COGGING模块对钼金属棒材的径向精锻过程进行模拟,确定合理的工艺参数,并对模拟结果进行分析.结果表明:本研究提出的用于模拟结果分析的锻透性判据合理,工艺过程和参数的确定方法正确.研究表明:影响锻透性的主要因素为道次压入量和锤头倾角;影响锻件表面质量的主要因素为轴向送进速度和旋转角度. 相似文献
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MICROSTRUCTURALEVOLUTIONANDCONTROLINSUPERALLOYFORGINGSR.Noel,D.Furrer,G.ShenandJ.Lemsky(LadishCo.,Inc.,P.O.Box8902,Cudahy,WI5... 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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1 INTRODUCTIONDieselengineswithhigh powerarewidelyused ,especiallyintrucksandnavalvessels.Pistonskirtisoneofthekey partsinadieselenginebecauseitworkstogetherwiththecylinderwallfordeliveringpower,guiding ,sealing ,bearingsidepressureandsoon .Butthepistonski… 相似文献
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M.S. Yeh H.Y. Lin H.T. Lin C.B. Chang 《Journal of Materials Processing Technology》2006,180(1-3):17-22
A novel micro-forming method, combining a metal's superplastic behavior with hot embossing technology, has been developed for manufacturing micro components from a fine-grained Zn–22Al eutectoid alloy. The forging characteristics of this alloy have also been studied using a Gleeble simulation machine.
Experimental results indicated that neither fiber-flow lines nor internal cracks could be observed when the fine-grained Zn–22Al eutectoid alloy was forged at a temperature range from 150 to 200 °C under a compressive strain rate range from 0.6 to 0.006 s−1. A good dimensional accuracy for a mini compound spur gear was obtained by using hot embossing technology. Finally, a 5:1 mini reduction gear train was assembled. Its rotational motion was very continuous and smooth, indicating that the micro-forming method is a suitable technology for manufacturing micro metal components for Micro Electro Mechanical Systems (MEMS). 相似文献
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有限元模拟在汽车转向节锻造设计中的应用 总被引:1,自引:1,他引:0
针对汽车转向节,进行锻造过程三维有限元模拟,得到锻件内部温度场、应力场和应变场等参数.在此基础上,进行转向节锻造设计.实验表明模拟结果和实际成形过程吻合良好. 相似文献
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基于PRASAD提出的传统的二维加工图理论,建立考虑应变的三维加工图,描述功率耗散系数和流变失稳区域随应变速率、温度和应变的变化。三维加工图说明了材料的内禀可加工性,而有限元分析方法可得到材料在特定工艺条件下应力、应变、应变速率及金属流动情况,说明了由模具形状和工艺条件决定的应力状态可加工性。基于此,提出一个新的由材料驱动的热变形可加工分析方法,联合考虑有限元和三维加工图,可以说明整个热加工过程的材料可加工性(包括应力状态可加工性和内禀的可加工性)。通过此方法,研究难变形金属镁合金的热锻过程,包括复杂热锻直齿锥齿轮的三维热力耦合有限元和三维加工图的集成模式。基于得到的研究结果,成功进行了热锻试验。试验表明新的方法用于确定最佳工艺参数是合理的。 相似文献
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介绍了差温无模锻造技术在成形轴盘类锻件中的应用,分析了始锻温度、摩擦因数、加热区高度、热应变4个不同参数对坯料最终变形结果的影响。分析结果表明,提高始锻温度和摩擦因数有利于使坯料获得局部较大变形,而加热区高度和热应变对坯料最终变形结果无明显影响。 相似文献
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汽轮机叶片是将蒸汽能转换成机械功的关键部件,叶片精锻是叶片锻造的发展趋势.本文利用数值模拟方法,仿真了叶片金属在锻模型腔内的流动和成形过程,论述了摩擦条件对叶片精锻成形规律的影响.在锻坯金属变形充模的3个阶段,分析并讨论了不同的界面摩擦因子m对叶片模锻成形规律和模具失效的影响.数值实验结果表明:随着界面摩擦因子的增加,克服坯料金属界面流动阻力所需的附加模锻载荷增加,叶片锻件不同区域内的最大最小温度差、最大最小等效应变差,以及最大最小等效应力差增加;与此同时,锻模型腔局部最大等效应力和最大温度也增加. 相似文献
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在工业化生产条件下,采用半连续铸造、自由锻造、固溶和时效处理技术制备A l-4.6Zn-2.58Mg合金锻件。采用热加工模拟方法优化该合金的热加工工艺。试验结果表明:该合金高温压缩变形时的流变应力随变形温度的升高而减小,随变形速率的提高而增大。合金在420℃以下热变形,热变形组织主要为动态回复组织;在420℃以上热变形,热变形组织有动态再结晶发生。在400℃~420℃之间热压缩变形,变形抗力比较小;380℃~420℃时铸态塑性最好。该合金较适宜的热加工温度范围为400℃~420℃。 相似文献