H65-IF-H65层状复合材料力学行为的尺寸效应

Sizes effect on the tensile behaviors of H65-IF-H65 laminated metal composites

  • 摘要: 采用轧制结合退火的方式制备了厚度为0.12 mm、标距宽度为1~9 mm的H65黄铜/IF钢/H65黄铜3层层状复合金属材料(H65-IF-H65),并借助电子背散射衍射(EBSD)、数字图像相关(DIC)技术、常规拉伸、原位拉伸和SEM等手段分析了试样宽度对复合材料力学行为的影响。研究结果表明:层状复合材料中的H65-IF界面在退火过程中未发生元素扩散,界面结合方式为机械结合。随着标距宽度由9 mm 逐渐降低至1 mm,材料的抗拉强度、屈服强度基本保持不变,但总延伸率、均匀延伸率和不均匀延伸率分别由30.3%、23.4% 和6.9%下降至20.3%、18.8%和1.5%,加工硬化能力迅速减弱。与此同时,材料的应变集中程度逐渐加剧,拉伸断口上的韧窝带宽度变小且带内的韧窝数量和尺寸也明显减小,呈现出显著的尺寸效应。H65-IF-H65层状复合材料的尺寸效应主要源于剪切应力的交互作用随着标距宽度的降低而被抑制,裂纹更易沿单道剪切带快速扩展而导致塑性下降。

     

    Abstract: The H65 brass alloy-interstitial free steel-H65 brass alloy (H65-IF-H65) laminated metal composites (LMCs) of 0.12 mm thickness and 1-9 mm gauge widths were prepared by rolling combined with annealing. The electron back scatter diffraction (EBSD), digital image correlation (DIC) technology, conventional tensile testing, in-situ tensile testing and SEM were used to analysis the effect of specimen width on the mechanical behavior of the H65-IF-H65 LMC. The results show that the H65-IF interface is mechanical bonded without elements diffusion during the annealing process. As the gauge width gradually reduced from 9 mm to 1 mm, the tensile strength and yield strength remain basically unchanged, meanwhile the total, the uniform, and the non-uniform elongations decrease from 30.3%, 23.4% and 6.9% to 20.3%, 18.8% and 1.5%, respectively. The work hardening ability also decreases rapidly. Moreover, the strain of the H65-IF-H65 LMCs is gradually concentrated. On the tensile fracture, the width of the dimple band and the number and size of dimples within it also decrease significantly, which indicates a significant size effect. The main reason of sample sizes effect on the tensile behaviors of H65-IF-H65 LMCs is that the interaction of shear stress is inhibited with the decrease of the gauge width. The cracks are more likely to spread rapidly in the single shear band and result in a decreased ductility.

     

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