稀土对V微合金重轨钢高温塑性的影响

Effect of RE on Hot Plasticity of V Microalloying Heavy Rail Steel

U76CrRE钢(/%:0.71～0.80C、0.50～0.80Si、0.80～1.10Mn、0.04～0.10V、0.25～0.35Cr、0.02RE)和U75V钢(/%:0.70～0.78C、0.50～0.70Si、0.75～1.05Mn、0.04～0.08V)的冶炼工艺流程为铁水预处理-150 t复吹转炉-LF-VD 280 mm×380 mm连铸,LF精炼后通过喂稀土包芯线加入稀土。对钢的铸坯进行热塑性试验结果表明,加入稀土主要在第Ⅲ脆性区提高V微合金重轨钢的高温塑性,950～1225℃U76CrRE钢和U75V钢的平均断面收缩率Z值分别为83.34%和65.17%,1250℃U76CrRE钢和U75V钢的Z值分别为58%和12%。为防止铸坯出现裂纹,铸坯的矫直温度应≥900℃。

Steelmaking flow sheet for steel U76CrRE （/% ： 0. 71 - 0. 80C, 0. 50 - 0. 80Si, 0. 80 - 1.10Mn, 0. 04 0.10V, 0.25 -0.35Cr, 0.02RE） and steel U75V （/%： 0.70 -0.80C, 0. 50 - 0. 70Si, 0.75 - 1.05Mn, 0.04 -0. 08V） is hot metal pretreatment-150 t top and bottom combined blown converter-LF-VD-280 mm × 380 mm bloom cast- ing, and RE is added in steel by feeding cladding RE wire after LF refining. The simulation test results on hot plasticity of steel casting bloom show that the hot plasticity of V microalloying heavy rail steel is increased by adding RE mainly in m brittle zone, at 950 -1 225 ℃ the average reduction of area Z value of steel U76CrRE and steel U75V is respectively 83.34% and 65.17% , and at 1 250 ℃the Z value of steel U76CrRE and steel U75V is respectively 58% and 12%. In order to prevent forrnin crack of casting bloom, the strengthening temperature of castin~ bloom should be ≥900 ℃.