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    缺口形状对铁基烧结材料冲击韧度的影响

    Influence of Notch Shapes on Impact Toughness of Fe-based Sintered Material

    • 摘要: 冲击韧度是评价材料性能的一个重要指标,同种材料在不同缺口形状下的冲击韧度是不同的。对不同缺口形状的铁基烧结材料进行了室温冲击试验,研究了缺口形状对冲击韧度、冲击断口形貌以及断口附近裂纹微观形貌的影响,试样的缺口形状有半圆型、U型、Ⅰ型、V型和无缺口5种,其中V型缺口的缺口角度又有45°,90°,120° 3种。结果表明:无缺口试样的冲击韧度最大,其平均值为9.86 J·cm-2,远远超出有缺口试样的;半圆型缺口试样的冲击韧度为2.70 J·cm-2,U型缺口试样的冲击韧度为2.46 J·cm-2,较半圆型缺口试样的略小;Ⅰ型和3种V型缺口试样的冲击韧度相差甚小,且比U型缺口试样的要低;无缺口试样的冲击断口有明显塑性变形,断口附近产生的裂纹多,分布范围较广;有缺口试样的冲击断口塑性变形不明显,断口附近裂纹少,且分布范围局限在断口处。

       

      Abstract: Impact toughness is one of the important indexes to judge properties of the material. The impact toughness values of the same material under different notch shapes are different. The effect of notch shapes on the impact toughness, fracture morphology and micro crack morphology near the fracture surface was investigated by the impact test at room temperature. There were five kinds of notch shapes, i.e., semicircular-type notch, U-type notch, I-type notch, V-type notch and no notch, and the V-type notch had three kinds of angle:45°, 90° and 120°. The results show that the average value of impact toughness of the no notch specimen was 9.86 J·cm-2 which was far beyond the impact toughness of notch specimens. The impact toughness values of semicircular-type notch specimen and U-type notch specimen were 2.70 J·cm-2 and 2.46 J·cm-2 respectively, and the latter was a bit smaller than the former. The impact toughness values of I-type notch and three kinds of V-type notch specimens were very similar, and they were lower than that of U-type notch specimen. The impact fracture of no notch specimen had obvious deformation, many cracks generated near the fracture, and the cracks distributed widely. However, the plastic deformation of impact fracture of the notched specimen was not obvious, there were a few cracks near the fracture, and the cracks were limited near the fracture.

       

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