共查询到20条相似文献,搜索用时 859 毫秒
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将轧制差厚板应用于梁类零件的制造能够实现汽车轻量化,但同时也带来了更为复杂的回弹问题。为了掌握差厚板梁类零件的回弹机理并获取各种工艺参数对回弹的影响规律,通过仿真与试验手段研究差厚板U型件纵向弯曲回弹问题。首先,建立差厚板U型件纵向弯曲成形与回弹有限元模型,完成成形与回弹过程仿真,并通过冲压试验对仿真结果进行验证,讨论差厚板回弹分布情况及其原因,分析退火工艺对差厚板回弹的影响规律及内在机理。接着,基于差厚板U型件回弹仿真结果,进行正交试验设计,在此基础上完成回弹影响因素的灰色关联分析,获取各因素的影响水平以及优化的参数组合。最后,完成BP神经网络模型的构建,实现差厚板U型件的回弹预测。研究结果表明,双斜率退火工艺能够减小差厚板的回弹,并且使得回弹分布更加均匀。灰色关联分析获取的最优工艺参数组合为过渡区位置-20 mm、过渡区长度50 mm、板料厚度1.6/2.0 mm、板料尺寸80 mm×230 mm,采用最优工艺参数组合成形的差厚板U型件可以获取更低水平的回弹量。不同工艺参数对差厚板U型件弯曲回弹的影响程度按降序排列为板料尺寸、过渡区位置、过渡区长度、板料厚度。建立的神经网络模型具有... 相似文献
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高强度高塑性是汽车用钢发展的主要趋势.Fe-Mn-Al-Si系TRIP/TWIP钢、Fe-Mn-C系TWIP钢和Fe-Mn-Al-C钢具有高的强度、优良的塑性和成形性,为新一代汽车材料.近年来,这些奥氏体汽车用钢的研究与开发受到了高度重视.本文对高锰TRIP/TWIP钢的组织性能、晶体学行为、强韧化机制、应变硬化行为和高速变形方面的研究工作进行了综述. 相似文献
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TWIP钢的拉伸应变硬化行为 总被引:3,自引:0,他引:3
采用静态拉伸、金相组织观察方法研究了5种不同锰含量的TWIP钢的拉伸应变硬化行为.结果表明:5种钢的真应力与真应变不遵循Hollomond的线性关系,其中1号钢的应变硬化指数n值随真应变的增大先升后降,其它4种成分钢的n值随真应变的增大而提高.对于同一成分的钢,其n值均随应变速率的增大而减小.其微观变形机制是:随着锰含量的增加,孪晶形成逐渐起主导作用;拉伸前组织中有退火孪晶;随着变形的进行,产生大量的形变孪晶,孪晶与位错之间的交互作用与硬化率相协调,从而延迟了颈缩的产生,导致TWIP钢具有很高的均匀变形能力. 相似文献
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采用扫描电镜、透射电镜和电子背散射衍射技术对TWIP钢拉伸变形后的组织进行了观察和分析.研究结果表明,热处理后的TWIP钢中存在60%的退火孪晶,变形后孪晶量减少为32%.在拉伸过程中,具有退火孪晶的晶粒内部首先发生变形,产生的变形孪晶遗传了退火孪晶的取向.变形过程中孪晶和位错相互作用、孪晶和孪晶相互作用以及孪晶取向改变引发滑移的综合结果使TWIP钢同时获得高塑性和高强度,因此变形过程中孪生变形是TWIP钢的主要变形机制. 相似文献
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In order to grasp the springback rule of TRB (tailor rolled blank) parts after forming, the springback behavior of TRB was investigated by integrating such three means as theoretical research, numerical simulation and stamping experiments. Fundamental theories of springback were analyzed. The stamping and springback processes of annealed 1.2/2.0 mm TRB, 1.2 mm and 2.0 mm plates for U-channel were simulated, and the simulation results were compared with the experiments. The results indicate that the springback of TRB falls in between those of the 1.2 mm and 2.0 mm plates. It is desirable for the TRB U-channel to have die clearance of 1.1 times maximum blank thickness and friction coefficient of about 0.12, and longer thickness transition zone is preferable. The simulation data demonstrate reasonably good agreement with the experiments. 相似文献
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The springback of tailor rolled blanks with quenching and partitioning steels was investigated.In order to find out the springback behavior and related influence factors for the novel sheets,both experimental and simulation methods have been used to compare and analyze the springback characteristics of equal thickness blanks and tailor rolled blanks in U-channel forming.From the results,the overall springback angles of tailor rolled blanks at thin and thick sides are respectively 106.79° and 99.705°,which are both lower than those of the corresponding equal thickness blanks.Due to the existence of the thickness transition zone,the stress distribution in thin and thick sides of blanks is changed.The location of dangerous region in thin side of tailor rolled blanks is closer to the end of side,and the thick side moved to the middle of straight wall,which are different with the equal thickness blanks.Afterwards,the released quantitles of tangential stress and strain per unit section of blank are adopted to calculate relative springback angles and give novel evaluation criteria for qualitatively analyzing the amount of springback angles.By comparing the results,it shows that the tangential strain method is more suitable for the actual situation. 相似文献
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《钢铁研究学报(英文版)》2016,(6):525-530
The stretch bending properties of a new Z-section stainless steel profile were investigated by simulation.The causes of the forming defects,such as section distortions and poor contour precision,were analyzed,and the corresponding controlling methods were proposed.The results show that the main forming defects for the stretch bending of the Z-section profile were the flange sagging,the sidewall obliquing inward,the bottom surface upwarping,and the bad contour accuracy;the cross-section distortions were mainly induced by the shrinkage of the sidewall,which could be eliminated by increasing the sidewall height of the profile reasonably;the poor contour precision was mainly due to springback,which could be controlled by modifying the die surface based on the springback amount;for the investigated bending beam,the proper sidewall height compensation was 2mm,and the suitable die surface modification amount was 1.2times of the springback amount,when the elongation was 10% of the initial profile length.Stretch bending tests were conducted on a new type of die with adjustable bending surfaces,and high quality components were achieved,which verified the effectiveness of the defect controlling measures. 相似文献
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Wei Gan S. S. Babu Nick Kapustka Robert H. Wagoner 《Metallurgical and Materials Transactions A》2006,37(11):3221-3231
The application of advanced high-strength steels (AHSS) has been growing rapidly in the automotive industry. Because of their
high-strength, thinner sheet metals can be used for body components to achieve both weight savings and increased safety. However,
this will lead to greater springback deviation from design after the forming operation. Fundamental understanding and prediction
of springback are required for springback compensation and tooling design. While various types of continuum mechanics based
models have been proposed to simulate the mechanical behavior of advanced high-strength steels, few of them consider microstructural
effects such as material heterogeneity. In this study, through sheet thickness strength variation has been observed in DP
780 and TRIP 780 steels. Finite-element simulation indicates that the through thickness effect (TTE) can have a significant
impact on the springback behavior of these sheet metals. This is verified through our experimental work using draw-bend testing.
The results suggest that microstructural effects should be considered to accurately simulate springback of AHSS. Based on
these results, implications of different microstructural designs will be discussed. 相似文献
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Seokmin Hong Sang Yong Shin Hyoung Seop Kim Sunghak Lee Sung-Kyu Kim Kwang-Geun Chin Nack J. Kim 《Metallurgical and Materials Transactions A》2013,44(2):776-786
In the present study, delayed fracture properties of a high-Mn TWinning Induced Plasticity (TWIP) steel and two Al-added TWIP steels were examined by dipping tests of cup specimens in the boiled water, after which the microcrack formation behavior was analyzed. The TWIP steels contained a small amount of elongated MnS inclusions, spherical-shaped AlN particles, and submicron-sized (Fe,Mn)3C carbides. Since MnS inclusions worked as crack initiation sites, longitudinal cracks were formed along the cup forming direction mostly by MnS inclusions. These cracks were readily grown when high tensile residual stresses affected the cracking or hydrogen atoms were gathered inside cracks, which resulted in the delayed fracture. In the Al-added steels, MnS inclusions acted as crack initiation and propagation sites during cup forming or boiled-water dipping test, but residual stresses applied to MnS might be low for the crack initiation and growth. Thus, longitudinal cracks formed by MnS inclusions did not work much for delayed fracture. AlN particles present in the Al-added steels hardly acted as crack initiation or growth sites for the delayed fracture because of their spherical shape. 相似文献
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《钢铁研究学报(英文版)》2016,(12):1249-1254
Research on the formability of tailor rolled blank (TRB)is of good practical significance and application value because of the enormous potential of TRB in the aspect of automobile lightweight.However,the forming of TRB is problematic because of the varying properties;especially,springback is a main challenge.The transverse bending (bending axis is perpendicular to the rolling direction)of TRB U-channel was studied through simulation and experiment.The forming characteristics of TRB U-channel during transverse bending were analyzed.The mecha-nisms of forming defects,including bending springback and thickness transition zone (TTZ)movement,were re-vealed.On this basis,effects of blank geometric parameters on springback and TTZ movement were discussed.The results indicate that springback and TTZ movement happen during transverse bending of TRB U-channel.Nonuni-form stress distribution is the most fundamental reason for the occurrence of springback of TRB during transverse bending.Annealing can eliminate nonuniform stress distribution,and thus diminish springback of TRB,especially springback on the thinner side.Therefore,springback of the whole TRB becomes more uniform.However,annealing can increase the TTZ movement.Blank thickness and TTZ position are the main factors affecting the formability of TRB U-channel during transverse bending. 相似文献
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Seokmin Hong Sang Yong Shin Hyoung Seop Kim Sunghak Lee Sung-Kyu Kim Kwang-Geun Chin Nack J. Kim 《Metallurgical and Materials Transactions A》2012,43(6):1870-1883
In the present study, a high Mn twinning induced plasticity (TWIP) steel and two Al-added TWIP steels were fabricated, and
their microstructures, tensile properties, and cup formability were analyzed to investigate the effects of Al addition on
deformation mechanisms in tensile and cup forming tests. In the high Mn steel, the twin formation was activated to increase
the strain hardening rate and ultimate tensile strength, which needed the high punch load during the cup forming test. In
the Al-added TWIP steels, the twin formation was reduced, while the slip activation increased, thereby leading to the decrease
in strain hardening rate and ultimate tensile strength. As twins and slips were homogeneously formed during the tensile or
cup forming test, the punch load required for the cup forming and residual stresses were relatively low, and the tensile ductility
was sufficiently high even after the cup forming test. This indicated that making use of twins and slips simultaneously in
TWIP steels by the Al addition was an effective way to improve overall properties including cup formability. 相似文献
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The mechanical properties of austenitic high Mn Twinning Inducted Plasticity (TWIP) steel provide an excellent combination of strength and ductility when tested in uni‐axial tension. The performance of TWIP steel during some critical formability tests such as deep drawing, bulge test and cutting edge stretching has not yet been studied extensively. In this contribution, the stretch‐flangeability of Fe18Mn0.6C1.5Al TWIP steel and Ti Interstitial‐Free (IF) steel were studied by means of hole expansion test. In‐situ strain analysis and Infra‐red (IR) thermography were carried out during the test. It was found that TWIP steel, despite having a higher uniform elongation in uniaxial tension, had poorer hole expansion properties than Ti IF steel. Strain distribution analysis revealed that the hole edge deformed in a deep drawing mode which was similar to a tensile deformation. Away from the hole edge, the deformation mode changed gradually from deep drawing to stretch forming mode. The IR‐thermography of TWIP steel revealed a high degree of adiabatic heating which was absent in the case of IF steel. The crack associated with the edge fracture revealed a local temperature increase at the crack tip of up to 92°C. Two types of hole edge preparations were studied. A high quality hole edge finish resulted in a better hole expansion performance. The fractography of the crack plane surface of TWIP steel and Ti IF were also studied by SEM, and revealed a plastic failure mode in both cases. 相似文献
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In the present work, advanced high strength and high ductility TRIP/TWIP steels with different manganese concentrations were studied. The microstructures of these steels were evaluated prior to and after deformation and the mechanical properties of these steels were determined. The microstructure analysis indicated that both TRIP and TWIP effects appeared in the steel with lower Mn content, while the TWIP effect was the dominant deformation mechanism in the steel with a higher Mn content, with many deformation twins formed during the deformation. In addition, the forming limit diagrams of these steels were recorded and the results showed an excellent formability. 相似文献