球墨铸铁后继屈服面演化的试验研究

发布时间：2018-06-15 05:32

本文选题：后继屈服面 + 平移应变　；参考：《广西大学》2017年硕士论文

【摘要】：本文选用球墨铸铁QT600-7薄壁圆管试样,采用多试样法,通过不同的拉扭比例进行初始屈服面试验和比例路径、非比例路径预加载后继屈服面试验。其中,比例路径包括预拉伸、预扭转和预拉扭,非比例路径沿菱形加载。通过对初始屈服面和后继屈服面的分析,研究预加载路径、预变形程度和平移应变取值对后继屈服面演化的影响。同时,研究塑性应变增量取值对塑性流动方向的影响,并探讨初始屈服面和后继屈服面上塑性流动方向与加载面正交方向的相关性。试验研究结果表明:1.后继屈服面往预加载方向移动,平移应变越小,移动的越多。预变形程度对小平移应变屈服面的变形影响较大,预变形程度越大,屈服面的变形也越大。平移应变取值越小,后继屈服面往预加载方向移动越多,变形也越大;在预加载方向出现“尖角”现象,在预加载反方向出现“内凹”或扁平现象。随着平移应变取值的增大,后继屈服面逐渐接近初始屈服面。2.塑性应变增量取值越大,塑性流动方向越稳定。当平移应变较大时,不同的平移应变对塑性流动方向的影响较小。后继屈服面上的塑性流动方向与加载面正交方向的相关性,与屈服面的变形程度有关,屈服面变形越小,两者的相关性越好。
[Abstract]:In this paper, the ductile iron QT600-7 thin wall tube specimen is selected, and the initial yield surface test and proportional path test are carried out by different tensile and torsional ratios, and the subsequent yield surface tests are carried out by non-proportional path preloading. The proportional path includes prestretching, pretorsion and pretension, and the non-proportional path is loaded along a diamond. Based on the analysis of the initial yield surface and the subsequent yield surface, the effects of the preloading path, the degree of predeformation and the translation strain on the evolution of the subsequent yield surface are studied. At the same time, the influence of plastic strain increment on the direction of plastic flow is studied, and the correlation between the direction of plastic flow and the orthogonal direction of loading surface on the initial yield surface and subsequent yield surface is discussed. The experimental results show that: 1. The subsequent yield surface moves towards the preloading direction, the smaller the translation strain, the more the displacement. The degree of predeformation has a great influence on the deformation of the yield surface of small translation strain, and the greater the degree of predeformation, the greater the deformation of the yield surface. The smaller the translation strain is, the more the subsequent yield surface moves to the preloading direction, and the bigger the deformation is, the "sharp angle" occurs in the preloading direction and the "concave" or flattened phenomenon occurs in the reverse direction of preloading. With the increase of translation strain, the subsequent yield surface is close to the initial yield surface. The larger the plastic strain increment is, the more stable the plastic flow direction is. When the translation strain is large, the effect of different translation strain on the direction of plastic flow is small. The relationship between the direction of plastic flow and the orthogonal direction of loading surface is related to the degree of deformation of yield surface. The smaller the deformation of yield surface, the better the correlation between them.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG143.5;TG115.5

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