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采用化学成分分析、热力学计算、显微观察、硬度测定的方法,研究了稀土铈在氧和硫质量分数均小于0.000 6%的超洁净IF钢中的存在状态,以及铈对钢的Al2O3夹杂物、显微组织和硬度的影响机理。结果表明,当铈质量分数为0.006 1%~0.009 3%时,铈的固溶量为0.004 1%~0.006 7%,约70%的铈以固溶形态存在,其余的铈以夹杂物形态存在,钢中不存在铈铁金属间化合物。铈能够将Al2O3夹杂物转化为尺寸较小的球状Ce Al O3夹杂物,具有变质夹杂物的作用。铈具有改善IF钢的显微组织的作用,钢中铈的固溶量越大,晶粒越细。与不含铈的IF钢相比,当钢中铈质量分数为0.006 1%和0.009 3%时,钢的洛氏硬度分别提高了7.6%和12.7%。
The existence of rare earth cerium in ultra-clean IF steel with both oxygen and sulfur contents less than 0.000 6% was studied by means of chemical composition analysis, thermodynamic calculation, microscopic observation and hardness measurement. The effects of cerium on Al2O3 inclusion , The mechanism of microstructure and hardness. The results show that when the mass fraction of cerium is 0.006 1% to 0.009 3%, the solid solution of cerium is 0.004 1% to 0.006 7%. About 70% of cerium exists in solid solution and the rest of cerium exists as inclusions There is no cerium-iron intermetallic compound in the steel. CeO 2 can transform Al 2 O 3 inclusions into spherical Ce Al O 3 inclusions with smaller size and have metamorphic inclusions. Cerium has the effect of improving the microstructure of the IF steel, the greater the amount of solid solution of cerium in the steel, the finer the grain. Compared with the IF steels without cerium, the Rockwell hardness increases by 7.6% and 12.7% respectively when the mass fraction of cerium in the steel is 0.006 1% and 0.009 3%.