关键词: 42CrMoTiB钢, 稀土, 夹杂物, 力学性能

Abstract: The test steel 42CrMoTiB and RE microalloying steels 42CrMoTiBRE (/% : 0.41 -0.43C, 0. 36 ~0. 38Si, 0.59~0.72Mn, 0.018 ~ 0.020P, 0.005 ~0.010S, 1.08-1. 13Cr, 0. 16~0. 19Mo, 0. 06 ~ 0.08Ti, 0. 003 ~ 0.004B, 0~ 0. 020Ce or Sm, 0.001 3 ~0.001 5 T [O]) are melted by an 150 kg vacuum induction furnace, casting average cross section 165 mm x 165 mm ingot then forged to 120 mm x 120 mm billet. The effect of Ce or Sm on inclusions and mechanical properties of steel 42CrMoTiB forged billet is studied. Results show that as compared with non-adding RE steel 42CrMoTiB, the inclusion amount in steel 42CrMoTiBRE with adding 0. 18RE ( RE content in steel- 0. 019% ~0. 020% ) decreases obviously ,the inclusion rating units of heavy series A, B and D respectively decrease from 0. 5, 2. 0 and 0. 5 to 0, 0 ~ 0. 5 and 0, and that of thin series respectively decrease from 0. 5, 1. 5 and 2. 0 to 0, 1. 0 and 1. 0; The morphology of inclusions in steel is modified by adding RE to form spherical RE oxysulfide ； and the plasticity and toughness of steel markedly increase by adding RE, as compared with non-adding RE steel 42CrMoTiB the transverse reduction of area (Z) and Charpy V-notch impact energy of steel 42CrMoTiBCe increase respectively from 22% and 17 J/cm² to 30% and 28 J/cm².