共查询到18条相似文献,搜索用时 171 毫秒
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基于三点弯曲的马氏体超高强钢弯曲性能试验 总被引:1,自引:0,他引:1
基于三点弯曲试验,研究了马氏体超高强钢的弯曲性能。利用二分法原理安排了"基于凸模尺寸"的试验。得到了不同弯曲角度下、以最小相对弯曲半径为表征的弯曲成形性能,并分析了其影响因素。对于1180 MPa级别及以下马氏体钢,在120°弯曲角及以下,均有Rmin/t1。对于1300MS和1400MS,Rmin/t≥2.5;且大于90°弯曲角后,弯曲性能对弯曲角度不敏感。各向异性对马氏体超高强钢最小相对弯曲半径的影响显著,沿轧制方向(L)的弯曲性能优于垂直于轧制方向(T);各向异性指数不能准确地表述马氏体超高强钢不同方向的弯曲变形行为和弯曲性能差异。随着强度的升高,断后伸长率接近线性下降,弯曲变形时相对弯曲半径值增大,弯曲性能下降,但并无很好的线性关系。 相似文献
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采用光学显微镜、单向/拉压、万能成形、三点弯曲等试验机检测了780~1180 MPa级双相钢的显微组织、力学性能、FLC(成形极限曲线)和冷弯性能。结果表明,随着双相钢的屈服强度增加,其伸长率、n值和r值降低,晶粒细化,马氏体含量增加,平面应变成形极限值从22.7%下降至12.6%,拉伸极限从15.8%下降至8.6%,三点弯曲最小相对弯厚半径从1.13增加到2.86;980 MPa级双相钢随着屈服强度增加,组织均匀性提高,胀形极限从22.8%增加到34.5%,最小相对弯厚半径从2.50减小到1.82;CR420/780DP、CR700/980DP、CR820/1180DP钢的包申格效应常数分别为0.82、0.78和0.79。CR420/780DP和CR820/1180DP钢在压缩过程中塑性变形初始阶段的加工硬化速率高于反向拉伸和单向拉伸塑性变形初始阶段的加工硬化速率。 相似文献
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基于成形特性的宝钢QP980试验研究及典型应用 总被引:3,自引:0,他引:3
深入解析了宝钢第3代高强钢QP980与第1代高强钢DP980和DP780的力学性能、成形极限和扩孔性能等冲压成形特性的差异.试验结果表明:QP980具有良好的塑性,伸长率约为20%,接近于DP780,比DP980高约5%;QP980钢成形极限较高,QP980-1.2 mm的FLD0约为27%,与等厚度的DP780相当,而QP980-2.0mm的FLD0约为34%,明显高于等规格的DP980;QP980钢具有良好的扩孔性能,保障了翻边和扩孔性能,且优于DP980.研究结果表明,宝钢QP980与DP980相同强度等级的基础上与DP780成形性能相当,良好的强塑积满足于外形相对复杂、强度要求高的车身骨架件和安全件,并在典型复杂超高强钢骨架件上成功试冲得到验证. 相似文献
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基于三点弯曲模具结构,设计可在线观察折弯件变形区域的简易装置,实现了对弯曲外表面微裂纹的实时观察;配合数显角度尺,实现了实时测量弯曲角度的功能。针对1 000MPa级别超高强度马氏体钢板进行三点弯曲实验,得到了以不同弯曲半径下最大弯曲角度为表征的弯曲成形性能,并分析了其影响因素。结果表明,超高强度钢随相对弯曲半径的增大,弯曲角度也变大,但随着材料强度升高,弯曲半径的敏感程度降低;最大弯曲角受轧向的影响较大,各向异性r值不能准确反映材料在弯曲平面应变状态下的各向异性特性;最大弯曲角随材料强度的升高而减小,但减小的幅度有所降低;最大弯曲角与延伸率无关联。 相似文献
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As the use of high strength sheet steels for automotive applications increases, there have been increasing occurrences of breakage on die radii at strains that are less than predicted by a conventional forming limit curve. To develop a better understanding of the problem, data from an angular stretch bend test were analyzed to determine the applied stress on a bend that caused breakage for a range of die radius, sheet thickness, and steel grade. The forming limit stress was calculated using a modified version of Stoughton's stress-based forming limit curve. The ratio of the applied failure stress to the forming limit stress is defined as the failure stress ratio. Regression analysis was used to determine the effect of the sheet thickness to die radius ratio (T/R) on the failure stress ratio for the different steel grades ranging from DDQ+ to DP980. The results were grouped due to commonality among various steel grades. Three predictive equations for (1) DP800, (2) DP980, and (3) all the other steel grades describe the behavior for all the steels in the study. It is found that breakage on a die radius for high strength steels such as DP600, DP800, and DP980 is typically a result of low values of the forming limit stress. 相似文献
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随着汽车工业的发展,汽车用钢的强度不断提升,冷连轧机组传统的压下率分配和板形执行机构的设定方法已经不能满足生产要求。以唐钢1 740 mm冷连轧机组生产汽车用高强钢DP980为研究对象,针对冷连轧过程中频发的带钢跑偏断带问题进行了研究,得到热轧来料的楔形和强度不均、负荷分配不合理导致S1机架轧制力过高以及轧辊倾斜调整过于灵敏是导致高强钢跑偏断带的主要原因。为此,基于经典遗传算法,以前4机架轧制力平衡为优化目标,对该冷连轧机组压下率进行优化,同时将第1机架轧辊倾斜调整的限制范围和响应速度进行了调整。跟踪了1 760 t共86卷DP980高强钢的生产情况,带钢跑偏概率由40%降低为10%,且S1机架未出现断带事故;轧制速度由200 m/min以下提升至500 m/min,速度发挥系数提高300%以上,机时产量提高100%,大幅提升了高强钢的生产效率。 相似文献
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Andrey M. Ilinich Sergey F. GolovashchenkoLorenzo M. Smith 《Journal of Materials Processing Technology》2011,211(3):441-449
The objective of this study is to determine the influence of material anisotropy and trimming method on the total elongation of the trimmed edge of DP500 sheet steel. For various orientations, experimental analysis is carried out on rectangular shaped tensile test specimens featuring a polished edge on one side and a trimmed edge on the other side. It is shown that the total elongation in DP500 steel exhibits significant sensitivity to (1) specimen orientation with respect to rolling direction, and (2) trimming method employed. In particular, difference in total elongation between longitudinal and transverse orientations become more pronounced with increasing trim clearance for conventionally trimmed samples. Total elongation anisotropy, however, can be significant even at small trim clearances and when sheared surface of the blank has relatively good quality without the burr which is the case for samples trimmed by the technology with offal support and dulled upper trim edge. The observations provided herein may be instrumental in contributing to meaningful explanations for unexpected edge cracking problems observed in some DP500 stamping cases. Recommendations for manufacturing best practices are offered. 相似文献
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由于超高强度钢板具有高强度、高韧性等特性,在冲切过程中对模具材料的磨损更严重,因此比较不同模具材料在冲切超高强度钢板时的抗磨损性能并选择合适的模具材料显得尤为重要。采用平行镶块组装形式的模具进行DP780超高强度钢板的冲切试验,并对不同冲切次数时3种模具材料(CALDIE、YXM1、SLD)对应的冲切试样的断面质量进行统计,以此分析模具材料的抗磨损性能。试验发现:冲切试样毛刺高度的变化能较好地反映出模具材料的磨损情况,冲切间隙的变化会影响试样断面剪切带宽度变化。CALDIE镶块在冲切试验的前期冲切试样质量最好,但后期其对应的冲切试样毛刺高度明显增加,说明CALDIE的稳定磨损期较短,这也降低了总的抗磨损性能。SLD镶块对应的冲切试样塌角高度、剪切带宽度及毛刺高度均是最大,说明其抗磨损性最差。综合比较发现,在冲切DP780板料时,SLD抗磨损性能最弱,CALDIE最好,YXM1介于两者之间。 相似文献
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E. -Y. Kim H. S. Yang S. H. Han J. H. Kwak S. -H. Choi 《Metals and Materials International》2012,18(4):573-582
Finite element analysis (FEA) was conducted to capture the effect of the initial microstructure on strain-stress partitioning and void formation in DP980 steel during uniaxial tension. By using the technique of direct mapping of a filtered microstructure into finite element meshes, FEA can capture the heterogeneity of strain-stress partitioning in DP980 steel through the thickness direction during uniaxial tension. The damage characteristics were studied through scanning electron microscope observations of polished sections of failed tensile specimens. FEA was also used to reveal the effect of microstructure heterogeneity on the hot spots for void formation during uniaxial tension. 相似文献
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