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OCr13Ni4Mo是新开发出来的马氏体不锈钢,近年来,已在水轮机、船用推进器等大型铸锻件的生产中得到应用。但使用中发现,用这种钢生产的大型铸锻件存在着性能不均匀的问题:产品表面的δ、ψ和αK值较高,而心部却较低。为分析其原因,从φ1800mm法兰心部套料取样,加工成V型缺口标准夏比试样做冲击试验,观察断口。发现氮化铝沿晶析出导致的沿晶韧窝断裂是性能下降的重要原因。试料的化学成分见表1。
OCr13Ni4Mo is a newly developed martensitic stainless steel, in recent years, has been applied in the production of large castings and forgings such as hydraulic turbines and marine propellers. However, it has been found in use that large castings and forgings made from this steel have the problem of non-uniform properties: the surface of the product has higher δ, ψ and αK values and a lower center of the heart. In order to analyze the reason, samples were taken from the φ1800mm flange core pocket and processed into a V-notch standard Charpy sample for impact test to observe the fracture. It is found that the fracture of the intercrystalline dimples caused by the precipitation of aluminum nitride is an important reason for the decrease of the properties. The chemical composition of the sample in Table 1.