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23Co14Ni12Cr3Mo超高强度钢具有优异的强韧性配合,逐步取代现役的超高强度钢,被广泛地应用于起落架等航空关键承力构件中。研究了23Co14Ni12Cr3Mo超高强度钢的应力腐蚀开裂(SCC)行为,对该材料的安全可靠应用具有重要的意义。采用双悬臂(DCB)试样研究了23Co14Ni12Cr3Mo超高强度钢在3.5%NaCl溶液中的SCC分叉行为,为该材料在航空航天领域安全可靠地使用提供了理论数据。采用扫描电子显微镜(SEM)对试验开裂后的断口形貌进行了表征,采用X射线电子衍射技术(XRD)结合能谱(EDS)技术对腐蚀产物进行分析。结果表明应力腐蚀裂纹扩展分叉,断口形貌在裂纹扩展前期、中期和后期分别为穿晶(TG)形貌、穿晶伴随沿晶(IG)形貌并含有二次微裂纹以及沿晶脆性断裂。该超高强度钢腐蚀产物主要包括Fe、Cr、Co的氧化物,结合Co、Cr、Ni、Mo在应力腐蚀过程中的变化,讨论了裂纹扩展分叉机理。
23Co14Ni12Cr3Mo ultra-high-strength steel with excellent strength and toughness, and gradually replace the existing high-strength steel, are widely used in landing gear and other aviation key bearing components. Studying the stress corrosion cracking (SCC) behavior of 23Co14Ni12Cr3Mo ultra-high strength steel is of great significance to the safe and reliable application of this material. The SCC bifurcation behavior of 23Co14Ni12Cr3Mo ultra-high strength steel in 3.5% NaCl solution was studied by double cantilever (DCB) specimen, which provided theoretical data for the safe and reliable use of this material in aerospace field. The morphology of the fracture after cracking was characterized by scanning electron microscopy (SEM). The corrosion products were analyzed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDS). The results show that the stress corrosion crack propagates and bifurcates. The fracture morphology is transmutation (TG) morphology in the early, middle and later stages of crack growth. The transgranular inclusions along with intergranular (IG) morphology with secondary microcracks, fracture. The corrosion products of the ultra-high strength steel mainly include the oxides of Fe, Cr and Co, and the mechanism of crack propagation and bifurcation is discussed in combination with the changes of Co, Cr, Ni and Mo during stress corrosion.