Influence Of Normalization Process And Rare Earth On Microstructure And Precipitation Evolution Behavior Of High-grade Non-oriented Silicon Steel

Silicon steel is a very important soft magnetic alloy material in power electronics and military industry,and it is also one of the widely used metal materials.Among them,high-grade non oriented silicon steel is mainly used to make iron cores of large and medium-sized motors working under rotating magnetic fields,such as generators and motors.Its product quality is often considered as one of the symbols to measure the manufacturing level of a country’s special steel.In the process of producing silicon steel,steel mills should not only adopt high-purity and purified steelmaking process,but also have strict normalization process and annealing process.In addition,the Bayan Obo area in Baotou,Inner Mongolia,is rich in rare earth minerals,mainly lanthanide rare earths.The addition of Trace Rare Earths in silicon steel can improve its properties.In this paper,the non oriented silicon steel with 2.6% silicon content is taken as the research object,and the effects of normalizing process and the addition of rare earth Ce on the microstructure,texture and precipitates of hot rolled plate are mainly studied.The microstructure,texture,precipitates and inclusions of the hot rolled samples with the change of normalization process parameters were characterized by metallography,SEM,XRD and other detection methods.The results show that:(1)the recrystallization grain size of non oriented silicon steel with 2.6% silicon content is small and uneven at 940 ℃normalization temperature;The recrystallized grains grow unevenly at 1000 ℃normalization temperature,and large-size grains appear in the central layer;970℃ × The tissue grew evenly when normalized for 5min.(2)After normalizing,the texture type of hot-rolled plate changes little,and the strength of each texture changes.The {110}<001>texture of 1/4 layer of hot rolled plate decreases,and the {100}<001> texture gradually increases with the increase of normalization temperature;1/2 layer {110}<001> texture enhancement,{001}<110> texture and γ The texture is weakened.(3)After normalization,Mn S precipitation in hot-rolled plates can increase to more than 200 nm,and part of Mn S will adhere to Al N to form Mn S+Al N composite precipitation.(4)Under the same normalizing process,the recrystallization grain size of rare earth hot rolled plate is relatively small,and can further improve the heterogeneity of structure;At the same time,Ce and harmful elements such as oxygen and sulfur in molten steel form rare earth compounds with high melting points,which inhibit fine precipitation in silicon steel and reduce the number of inclusions.In addition,under the combined action of rare earth,the{100} and {110} planes in the thickness direction of the longitudinal section of the rare earth hot-rolled plate are beneficial to enhance the texture,and the {111} plane is unfavorable to weaken the texture strength.