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1、武汉科技大学硕士学位论文 第1II页AbstractThe inclusions in the steel had been studied in this paper using the idea of oxide metallurgytechnologyand the The steel was deoxidized by with different combinations of alloys to obtaindifferent type and distribution of inclusions with predominance achieved by oxide metall
2、urgytechnologyIn this paper,the precipitation of oxides during solidificial solidification process inmolten steel in the Ti-0 system，Mg一0 system，Ti-AIO system，Mg一舢一O system，Ti-Mg-Osystem，and Ti-M分越-0 system at 1 873K were systematically calculated and discussedThehigla-temperature melting experiment
3、s Was were carried out in the induction fimace iIl thelaboratory using different combinations of alloys to deoxidizeThe samples that deoxidized bydifferent combinations of alloys were analyzed by scanning electron microscope， energyspectrum analysis and Qwin image analysisThe shape，composition and s
4、ize distribution of theinclusions in the steel which deoxidized by different combinations of alloys were analyzed byscanning electron microscope，energy spectrum analysis and Qwin image analysis were studiedrespectivelyAccording to the results of thermodynamic calculation，when the ratio of the activi
5、ty oftitanium and aluminum ariadWas larger than 1 0 in the FeTi-A1-0 system at 1 873K thetitanium oxide could form in the steelAnd Ti203 could appear in the steel only when keepingthe activity of titanium anlO69When the anlaatl ratio Was larger than 63，the A1-Ticomplex oxide could form in the steelS
6、ingle A1203 inclusions could not exist in the steel at all when dissolved magnesium existedin the steel in the Fe-Mg一灿O systemThe existed inclusion Was MgOA1203 in the steel whenthe aimwas 002 and the aMgl Was in the range of367x105-464x104When afMg464x104，single MgO inclusion could formIn the Fe-Ti
7、Mg-O system，when the content of magnesiumWas very low,it Was easy for the complex inclusions of titanium and magnesium to formWhenthe content of magnesium Was a little higher,the MgO inclusions might formWhile the content of magnesiumM翻is O0003 in the Fe-Ti-Mg-A1-O system at 1 873KTi203 formed under
8、 the condition of keepingriO1Complex inclusions of MgAl204 couldform under the condition of keepingTi008 and its existing scale increasedwith the titanium content decreasingIn order to form MgTi204 inclusions，the aluminum contentmust be controlled below 008，and the titanium content must be adjusted
9、to an appropriate leveltooWhen the steel Was deoxidized by A1-MnSi-TiMg alloy,the mainly type of nonmetallicinclusions formed in the steel Was M92Ti04一MgTi204-MgAl204 complex spinel inclusionsWiththe increasing of aluminum content in steel，the composition of the spinel varied from Mg-Ti-0system to M
10、g-A1一O systemThe experimental results showed as followsMn and S in the steel formed a large number第页 武汉科技大学硕士学位论文of chainlike MnS，and the quantities of inclusions per unit area increased dramaticallySingleMnS always precipitated on the surface of oxides111e content of AI had a significant influenceo
11、n the composition of inclusions of steel which deoxidized by Ti-MgThe quantities ofinclusions in steel increased dramatically when the conten of aluminum increased(when thealuminum content increased from 0023to 0072the quantities of inclusions per unit areaincreased from 23 1 8 aram2 to 4924 amm2)Th
12、e number of the inclusions of MnS and spinelinclusions，and MnTi204 increased when the content of aluminum in the steel increasedTl：屺effects of magnesium to AITiMg complex deoxidized steel mainly showed勰follows11ledistribution and morphology of inclusions were changed with the magnesium content incre
13、asing们1e distribution of inclusions was uniforill in steelThe aluminumcontained inclusions，whichwere replaced by a single MgO and Mg-Ti一0 oxide inclusions in the steel were significantlyreducedWhen the magnesium content Was in a high level(for example【Ti】_01 38，【M羽=0004 1)，the oxides formed in the s
14、teel mainly were MgO and Ti-Mg-O complex oxides，the sulfides mainly were MnS and MgS111e main size distribution of inclusions changed from101xm)，特别是夹杂物含量较低时，明显降低钢的屈服强度，且同时降低钢的抗拉强度；当夹杂物颗粒小到一定尺寸(10sbar的相图与在空气中的相图相似，随着氧分压的降低，液相线温度也有所下降，同时，武汉科技大学硕士学位论文 第23页在炼钢温度及氧分压的范围内，钢中生成的Al-TiO复合夹杂物为A12Ti05；图23是通过计算
15、得到的1600。C下，FeA1TiO系统夹杂物的平衡相图，其中包括了铝钛含量的变化以及在不同的氧含量下的变化，其结果与上文计算的结果相吻合。图2。4【59】为WanYiM等人研究的1873K下FeA1TiO系统内A1203，Ti203，Ti305稳定相。2啪缄190011100pmE”口甚1500爰，枷菩：黧勰Omo2黼tooo伯o T7g瞄兰ffoo，o。毒tO=，伯900柚O2撇伯伯o，leoo暑15i，“曼10卜2，口00eukthr璀IkT蜕H砷(b)图22不同的氧分压下A1203-Ti203rri02系统相图图23 1600下计算得到的Fe-AI-TiO系统夹杂物平衡相图惜错蛳蛳礴错
16、嫩枷辩撇储嘲辨雠p；。-基1F第24页 武汉科技大学硕士学位论文图24 1873K下Fe-A1Ti-O系统内A1203，Ti203，Ti30s稳定区域CONG WANG等唧】人通过实验研究了TiAl比对FeA1TiO系统内夹杂物的成分、形态以及结构的转变行为。实验得到，当TiA1比维持在l4时，A1203为钢液中的唯一热力学稳定的氧化物相，实验结果表明因钛的加入，钢中会形成过渡的钛的氧化物，随着时间的延迟，钢中占主导地位的还是灿203，并且其夹杂物的变形不大，还可形成短暂的少量含钛的复合夹杂物；当TiAI比维持在l1时，A1203仍是钢液中的唯一热力学稳定的氧化物相，但是形成过渡的钛的氧化物更加明显，在实验中还伴随有球形夹杂物向不规则夹杂物转变的不可逆过程；当钢
