Nb对Cr-Co-Ni-Mo系超高强度齿轮钢组织和力学性能的影响

Effect of Nb on Structure and Mechanical Properties of Cr-Co-Ni-Mo Series High Strength Gear Steel

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℃7 h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33 J。

The studied Cr-Co-Ni-Mo gear steel （/%： 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, non-adding Nb or adding 0. 01 - 0. 03Nb） is steelmaking by 200 kg vacuum induction melting ＋ vacuum arc remehing process and rolling to Ф50 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 ℃ 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.