Ce对0.2C-0.5Si-1.5Mn钢液洁净度与夹杂物变性的研究

为提高低合金高强度钢的强、韧性能并扩大其应用范围,以应用广泛的0.2C-0.5Si-1.5Mn系低合金高强度钢为研究对象,采用Q345H型钢板为原料,在真空感应炉熔化后添加稀土元素(Ce),制备了4种不同Ce含量的低合金钢试样。通过实验分析和热力学计算,研究了Ce含量对0.2C-0.5Si-1.5Mn系低合金高强度钢液的净化度和夹杂物变性的影响规律。结果表明,钢液中Ce的质量分数在0.001%～0.045%时,钢的洁净度显著提高;当Ce的质量分数为0.012%时,可把钢中O、S脱除到0.000 9%、0.001 0%;同时,Ce使夹杂物球化、细化,可将15μm带棱角的Al2O3-SiO2夹杂物和原长条状、大体积的MnS夹杂物转变为1～2μm,甚至纳米级稀土复合夹杂物。同时还探讨了Ce元素在钢液中的洁净化和夹杂物变性机理。

Effect of Rare Earth Ce on the Purifying Degree and Inclusion Modification of 0.2C-0.5Si-1.5Mn Molten Steel

In order to improve strength and toughness of high strength low alloy steel and expand its application scope,the 0.2%C-0.5%Si-1.5Mn% steels were chosen as the research object.Low alloy steels with different content of Ce were prepared in vacuum induction furnace by refining after adding rare earth to Q345 H beam steel.Influence of Ce content on the purifying degree and inclusion modification of 0.2%C-0.5%Si-1.5Mn% Steel was investigated.The results show that when the content of Ce was 0.001%~0.045%(mass fraction),the cleanliness of steel increased significantly.When Ce content was 0.012%,O and S reduced to 0.000 9% and 0.001 0%,respectively;Inclusions were spheroidized and refined.Adding Ce,15 μm angular Al2O3-SiO2 inclusions and MnS of long strips and large volume were changed into RE compound inclusion of 1~2 μm or even nanometer size.At the same time,the mechanism of Ce on the purifying degree and inclusion modification of molten Steel was discussed.