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本文研究了AISI M2和AISI M7高速钢的断裂韧性。结果表明,这些钢的断裂韧性主要决定于奥氏体化温度和所达到的硬度。试验结果的重复性高。在一般工作硬度条件下M2和M7的断裂韧性大致相等。通过无缺口的冲击试验,表明M2钢比M7钢具有较高的冲击强度。用得到的数据对假设予先存在裂纹的断裂模型作了验证,结果表明这个模型与从M7钢获得的结果相一致,而与M2钢却不相符。因此,予先存在裂纹的假设对M2高速钢来说似乎是不合理的。此外,还对M2钢断裂开始产生的可能机理进行了简要的讨论。
In this paper, the fracture toughness of AISI M2 and AISI M7 high-speed steels is studied. The results show that the fracture toughness of these steels depends mainly on the austenitizing temperature and the hardness achieved. High repeatability of test results. The fracture toughness of M2 and M7 is roughly equal under the conditions of general working hardness. Through the unnotched impact test, M2 steel has higher impact strength than M7 steel. The obtained data validate the fracture model assuming preexistence of cracks. The results show that this model is consistent with the results obtained from M7 steel, but not with M2 steel. Therefore, the assumption of pre-existing crack appears to be unreasonable for M2 HSS. In addition, a brief discussion on the possible mechanism of M2 steel fracture initiation is also given.