碳和硼含量对低碳冷镦钢连铸坯高温力学性能的影响

Effect of Carbon and Boron Content on Mechanical Properties of Casting Bloom of Low Carbon Cold Heading Steel at Elevated Temperature

试验的低碳冷镦钢（/%：0.14～0.20C,≤0.20Si,0.3～1.0Mn,≤0.030P,≤0.035S,0～0.001 9B）连铸坯的生产流程为80 t BOF-LF-280 mm×325 mm坯连铸工艺。通过Gleeble-3500热模拟机研究了0.14%～0.20%C和0～0.001 9%B对该冷镦钢600～1 200℃力学性能的影响。结果表明,该钢第Ⅲ脆性区为700～900℃,当钢中C含量较高时,最低塑性的温度较低,硼促使该钢700～950℃脆性区出现两个低谷,但当硼含量增加到0.001 9%时,该钢的高温塑性得到改善。在850～1 200℃,各试验钢的塑性良好,适合较大程度的变形,矫直温度和热加工温度宜控制在850℃以上。

The production flowsheet for casting bloom of test low carbon cold heading steel （/% ： 0. 14 -0. 20C, ≤O. 20Si, 0. 3 - 1.0Mn, ≤0. 030P, ～〈0. 035S, 0 ～ 0. 001 9B） is 80 t BOF-LF-280 mm ～ 325 mm bloom casting process. The effect of 0. 14% ～ O. 20% C and 0 ～ 0. 001 9% B on mechanical properties of the cold heading steel at 600 ～ 1 200 ℃ has been studied by using Glccble-3500 thermal simulation machine. Results show that the III brittle zone of the steel is 700 -900 ℃, as the C content in steel is higher the temperature of minimum plasticity of steel is lower; the boron promotes to occur of two valleys in 700 -950 ℃ brittle zone, but as the B content in steel is up to O. 001 9%, the elevated tempera- ture plasticity of steel is improved. At 850 - 1 200 ℃ each test steel has better plasticity to be suit for larger deformation, therefore straightening and hot-working temperature should be controlled at more than 850 ℃.