关键词: 60Mn 钢, Φ450mm 圆铸坯, 高温断面收缩率

Abstract: The hot plasticity(reduction  of area)of steel  60Mn-0.61C,0.74Mn,0. 18Cr was  carried  out by  Gleeble-2000 dynanic themmo mechanical simulator using solidifying method. It was obtained that there were two low ductility regions  at high temperature - more than  1300 ℃ and 925~750 ℃.At temperature between 925 ℃ and 750 ℃,the nitride AlN and NbN precipitated at γ grainboundary and the procutectoid α- phase was distributed as net shaped in y+ a two phase region.With optimized process the Als in steel decreased to ≤0.010% from original ≤0.015%,by intensifying VD degas- sing  and  shielding  casting practice  the[N]  decreased to  40×10-⁶  from  60×10-⁶,and with  overheating  temperature  of molten  steel  decreasing  to  ≤35  ℃ from  ≤50  ℃,water ratio  decreasing  to  0.30 L/kg  from  0.40  L/kg,lowering  cast straightening force and keeping surface temperature of billet ≥900 ℃ before straightering,the rating of billet porosity decreased,the equiaxed zone ratio increased to 51.3% from 45.7% before optimized and internal crack ratio decreased to 1.7% from 5.2%,the quality of billet obviously improved.

Key words: Steel 60Mn,Φ450 nm Round Cast Billet,Reduction of Area at High Temperature