锰质量分数对Fe-Mn-C钢热物性参数的影响

Effects of w(Mn) on thermal properties of Fe-Mn-C steels

为促进Fe-Mn-C钢连铸技术的发展,对不同锰质量分数的Fe-Mn-C钢铸锭的热物性参数进行了研究。结果表明,0Mn钢的导热系数高于3Mn钢。低于750℃时,6Mn钢的导热系数最低;高于900℃时,6Mn钢的导热系数最高。3个钢种的平均线膨胀系数为1.0×10^(-5)~1.6×10^(-5)℃^(-1)。以Z<60%作为判据,6Mn钢的第Ⅲ脆性区为600~800℃,3Mn钢和0Mn钢的第Ⅲ脆性区分别为600~850℃和600~900℃。在6Mn钢和3Mn钢中,大量生成的形变诱导铁素体(DIF)导致低温区热塑性的恢复。然而,由于连铸矫直过程的应变速率较低,不能生成大量的DIF。因此在连铸过程中,低温区6Mn钢和3Mn钢的热塑性不能恢复。

The solidification structures and the thermal properties of Fe-Mn-C steel ingots containing different Mn mass fraction have been investigated to assist the development of the continuous casting technology of Fe-Mn-C steels. The re- suits show that the thermal conductivity of the 0Mn steel is higher than that of the 3Mn steel. The thermal conductivity of the 6Mn steel is the lowest in the three kinds of steels below 750 ~C and the highest above 900 ~C. The 0Mn steel has the highest value of the proportion of equiaxed grain zone area in the three kinds of steels, whereas the 3Mn steel has the lowest value of it in the steels. Mn has the effect of promoting the coarsening of grains. The mean thermal expansion co- efficients of the steels are at the range from 1.0 ~ 10-5~ 1.6 ~ 10-5 ~C-~. Using Z 〈60 % as the criterion, the third brittle temperature region of the 6Mn steel is 600 ~C to 800 ~C, whereas those of the 3Mn steel and the 0Mn steel are 600 ~C to 850 ~C and 600 ~C to 900 ~C, respectively. In the 6Mn and 3Mn steels, the deformation-induced ferrite（DIF） forming in sufficient quantities causes the recovery of the ductility at the low temperature end. However, since low strains are pres- ent when straightening, sufficient quantities of DIF cannot be formed. Thus, the ductility of the 6Mn and 3Mn steels can- not be improved during the continuous casting process.