Abstract: The studied Cr-Co-Ni-Mo gear steel (/% : 0.05 ~ 0. 15C, 4. 2 ~ 6. 3Ni, 14. 5 ~ 16. 2Co, 4. 2 ~ 6. 4Ct, 3. 8 〜5.3Mo, 0. 8 ~ 1. 5W, 0.1 ~0.4V, ≤ 0.005S,, ≤ 0. 008P, non-adding Nb or adding 0. 01 ~0. 03Nb) is steelmaking by 200 kg vacuum induction melting + vacuum arc remelting process and rolling to Φ50 mm bar products. The testing specimen is solid-solution-treated at 1 050℃ for 1 h and oil cooling, and cold-treated at -80℃ for 2 h , then aging-treated at 560 °C for 7 h. Results show that in steel bearing Nb, Nb microalloy carbon-nitride exists at grain boundary or sub-grain boundary, it has the fine grain strengthening function, as a result with adding 0. 01% ~ 0, 03% Nb the tensile, yield strength and impact energy of steel increase respectively from non-Nb steel 1 850 MPa, 1 598 MPa and 22 J to 2 057 MPa, 1 964 MPa and 33 J.

摘要： 所研究的Cr-Co-Ni-Mo齿轮钢(/%:0.05～0.15C,4.2～6.3Ni,14.5～16.2Co,4.2～6.4Cr,3.8～5.3Mo,0.8～1.5W,0.1～0.4V,≤0.005S,≤0.008P,不加Nb和加0.01～0.03Nb)由200 kg真空感应冶炼+真空自耗重熔冶炼,并轧成Φ50mm的棒材。试样经1 050℃ 1h固溶处理,油冷,-80℃ 2 h冷处理,再经560℃ 7h时效处理。结果表明,加Nb钢中,Nb在晶界或亚晶界以微合金碳氮化物存在,有细晶强化作用,加0.01%～0.03%Nb后钢的抗拉、屈服强度和冲击功分别由无Nb钢的1 850、1 598 MPa和22 J提高至2057、1 964 MPa和33J。