Abstract: The technological measures to control oxygen content of gear steel in 100 t EAF⁃LF⁃VD⁃CC⁃CR whole process are put forward. The rotary bending fatigue properties， fracture and inclusion size of gear steel 20MnCr5 with oxygen content 0．000 53％ ~ 0．001 45％ are investigated. The results show that the higher the oxygen content， the larger the size of maximum inclusion and the lower fatigue strength of steel， while [O] ≤0．001 0％ ，with [O] decreasing， the fatigue strength of steel decreasing within a narrow range； the critical inclusion size of the test steel without fatigue crack under the surface is 21 μm and the shallow zone 30 ~ 430 μm away from the surface is relatively safe zone， where inclusions are difficult to cause fatigue cracking．

Key words: Oxygen Content；20MnCr5 Gear Steel, Fatigue Strength； Critical Size of Inclusion

摘要： 提出了100 t EAF-LF-VD-CC-CR全流程控制齿轮钢氧含量的工艺措施；研究了0.00053%～0.00145%氧含量20MnCr5齿轮钢的旋转弯曲疲劳性能、断口和夹杂物尺寸。结果表明，钢中总氧含量越高，最大夹杂物尺寸也越大，疲劳强度越低，当[O]≤0.0010%时，随[O]降低，疲劳强度升高幅度较小；试验钢在表层不产生疲劳裂纹的临界夹杂物尺寸为21μm,距表面深度30～430μm的浅层区域为相对安全区域，其中的夹杂物很难引起疲劳开裂。

关键词: 氧含量, 20MnCr5 齿轮钢, 疲劳强度, 夹杂物临界尺寸