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为了研究非金属夹杂物对航空用超高强度钢性能的影响,采用扫描电镜原位观测的方法,跟踪观察了拉伸和低周疲劳载荷作用下两种航空用超高强度钢中不同种类、形态和尺寸的夹杂物导致裂纹萌生与扩展的微观行为.结果表明,对于单个TiN和AlN夹杂,在拉伸载荷作用下,裂纹均首先在夹杂内部萌生.夹杂面积越大,夹杂内萌生的裂纹条数越多,第1条裂纹萌生所需的应力越小.在疲劳载荷作用下,对于单个TiN夹杂,裂纹也首先萌生于夹杂内部.但对于以点链状形式存在的AlN夹杂,无论是在拉伸还是疲劳载荷作用下,裂纹均首先在点链状夹杂内部两夹杂之间的母材中萌生,然后沿点链状夹杂向两侧扩展.以点链状形式存在的夹杂对材料疲劳性能的危害比单个夹杂严重得多,夹杂物对材料疲劳性能的危害远大于对拉伸性能的危害.
In order to study the impact of non-metallic inclusions on the properties of ultra-high strength steels for aviation use scanning electron microscope in situ observation method to follow the tensile and low cycle fatigue load of two kinds of aviation superhigh strength steel of different types, The morphology and size of inclusions lead to the microcosmic behavior of crack initiation and propagation. The results show that for a single TiN and AlN inclusions, the cracks are first sprouted within the inclusions under the tensile load. The larger the inclusion area, the crack initiation inclusions The more the number of cracks, the smaller the stress required for the initiation of crack propagation in section 1. Under the action of fatigue loading, the cracks also initiate inside inclusions for single TiN inclusions, but for AlN inclusions existing in a chain-like manner, Under tensile or fatigue loading, the cracks are firstly initiated in the base material between the two inclusions in the chain-like inclusions and then spread along the point chain-like inclusions to both sides. The performance hazards are much more serious than the single inclusions, inclusions on the fatigue properties of the material far greater than the tensile properties of the hazards.