无取向硅钢中硫化物的析出机理

Precipitation Mechanism of Sulfide in Non-oriented Silicon Steel

结合无取向硅钢中硫化物的析出热力学、动力学计算和扫描电镜(SEM)、透射电镜(TEM)检测,系统研究了硫化物在无取向硅钢中的析出机理,并讨论了硫化物对退火过程中晶粒长大的影响。结果表明,无取向硅钢中硫化物以(Mn,Cu)S复合析出相为主。在凝固过程中,MnS和Cu_(2)S均不具备析出热力学条件。MnS先于Cu_(2)S在晶界形核,随着温度的降低将以位错形核为主。在均热过程中,w(Si+Al)≥2.5%的无取向硅钢中的MnS和w(Si+Al)≤1.6%的无取向电工钢中的Cu_(2)S主要在晶界形核。同时,均热过程中MnS在晶界的析出量远大于Cu_(2)S,Cu_(2)S主要在后续的热处理过程中析出。MnS和Cu_(2)S的Ostwald熟化研究表明,w(Si+Al)≥2.5%无取向硅钢中的MnS和Cu_(2)S对晶粒长大的影响明显大于w(Si+Al)≤1.6%无取向电工钢。

The precipitation mechanism of sulfide and the effect of sulfide on grain growth during annealing in non-oriented silicon steel were systematically studied based on the calculation of thermodynamics and kinetics,combined with scan electron microscopy(SEM)and transmission electron microscopy(TEM).The results indicate that sulfides in non-oriented silicon steel are mainly(Mn,Cu)S composite precipitates.In the solidification process,MnS and Cu_(2)S would not possess the precipitation thermodynamic conditions.MnS would preferentially nucleate at grain boundaries before Cu_(2)S,and dislocation nucleation will dominate as the temperature decreases.In the soaking process,MnS in w(Si+Al)≥2.5%non-oriented silicon steel and Cu_(2)S in w(Si+Al)≤1.6%non-oriented electrical steel are mainly nucleated at the grain boundary.Meanwhile,during the soaking process the precipitation amount of MnS is much larger than that of Cu_(2)S in the grain boundary,and Cu_(2)S would mainly precipitate in the subsequent heat treatment processes.Ostwald ripening calculations of MnS and Cu_(2)S show that the effect of MnS and Cu_(2)S in w(Si+Al)≥2.5%non-oriented silicon steel on grain growth is significantly greater than that of w(Si+Al)≤1.6%non-oriented electrical steel.