中文摘要：

23C014Ni12Cr3Mo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23C014Ni12Cr3Mo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23C014Ni1 2Cr3Mo超高强度钢在3.5％ NaC1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.

英文摘要：

With high strength and toughness,23Co14Ni12Cr3Mo ultra-high strength steel,instead of other ultra-high strength steels,is widely used in bearing components such as landing gears.It is of great significance for safe and reliable application of 23Co14Ni12Cr3Mo ultra-high strength by investigating its stress corrosion cracking （SCC） behavior.The bifurcation behavior in SCC propagation of ultra-high strength steel 23Co14Ni12Cr3Mo is investigated by using double cantilever beam （DCB） specimens in 3.5 ％ NaCl solution,which provides theoretical supports for the safety application of the material as landing gear.The SCC morphology is observed by using scanning electron microscopy （SEM） and the composition of corrosion products is analyzed by using X-ray diffraction （XRD） and energy dispersive spectrometer （EDS）.The results show that the corrosion crack propagates to bifurcations and the fracture morphology is transgranular （TG） brittle cracking at prophase of crack propagation,TG cracking along with i ntergranular （IG） cracking factors in some regions,especially some second cracks at metaphase,and TG and brittle cracking at anaphase.The corrosion products consist of Fe,Cr and Co oxides.Effects of the elements Co,Cr,Ni,and Mo on the crack propagation are discussed.