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采用带屏蔽的光学显微镜(OM)、扫描电子显微镜(SEM)和能谱仪(EDS)等手段对中子辐照后国产A508-3钢冲击功异常试样的冲击断口形貌、显微组织、晶粒尺寸、孔洞和第二相夹杂物进行了观察和分析,并探讨了产生异常的可能原因。结果表明,在本次辐照实验条件下(中子注量2.97×1019 n/cm2,辐照温度(290±15)℃,国产A508-3钢试样辐照前后的显微组织均为贝氏体组织,且晶粒尺寸未见明显变化,不是导致冲击功产生异常的主要原因,其直接原因可能是基体组织中体缺陷(孔洞)数量的差异;组织中的孔洞分为两种类型,一种为填充了Al2O3、MnS、Al-Mg-O三元化合物等层片状复合第二相粒子的孔洞,另一种为未填充任何第二相的空洞,且孔洞中第二相与基体结合较差,易导致材料韧性降低。
The impact fracture morphology of the domestic A508-3 steel with abnormal impact energy after neutron irradiation was observed by means of optical microscope (OM), scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). The microstructure , Grain size, voids and inclusions in the second phase were observed and analyzed, and discussed the possible causes of abnormalities. The results show that the microstructure of domestic A508-3 steel before and after irradiation is 2.97 × 1019 n / cm2 and 290 ± 15 ℃ There is no obvious change in the grain size, which is not the main reason that causes the impact energy to work abnormally. The direct reason may be the difference in the number of body defects (pores) in the matrix; the pores in the tissue are divided into two types, One is filled with Al2O3, MnS, Al-Mg-O ternary compounds lamellar composite second phase particles such as holes, and the other is not filled with any second phase of the cavity, and the hole in the second phase and the matrix The combination of poor, easily lead to reduced material toughness.