Research On Reduction Rate Control Of Thin-Gauge Grain-Oriented Silicon Steel

In recent years,with the progress of many power transportation projects,the country has gradually increased the energy efficiency rating requirements for transformers.Oriented silicon steel is the most used raw material for transformers,and its iron loss level directly affects the energy efficiency level of the transformer.Low-temperature slab heating to produce oriented silicon steel has the advantages of reducing pollution,lowering energy consumption,reducing production costs,and ensuring product quality.It is a hot spot in the production and research and development of oriented silicon steel in recent years.The iron loss value of oriented silicon steel is related to its thickness,and the thickness reduction can effectively reduce the iron loss level of oriented silicon steel,and can reduce the core volume of the transformer,so as to reduce energy loss and save manufacturing costs.In this paper,thin-gauge low-temperature grain-oriented silicon steel was prepared by simulating mass production in the laboratory.Using hot-rolled normalized plates of different thicknesses from a domestic steel plant as raw materials,they are prepared by using four kinds of one-time high-reduction cold rolling methods,decarburization annealing,nitriding and high-temperature annealing with a reduction rate of more than90.5%in the laboratory.Thin-gauge low-temperature grain-oriented silicon steel with the same thickness of 0.18mm.Using Zeiss Ax10 Axio metallurgical microscope to observe the metallographic structure and collect digital photos,and count the grain size of the sample at each stage,and study the evolution of the structure under different processes.Using the BRUKER D8 ADVANCE X-ray diffractometer 1/8 layer,1/4 layer and 1/2layer in the various stages of normalization,cold rolling,decarburzation and nitriding were analyzed for macro-texture,and the texture changes under different reduction ratios were studied.The EBSD components equipped with Sigma 300 scanning electron microscope were used to study the micro-texture of samples at various stages of decarburization,nitriding and high-temperature annealing.The NIM-2000E silicon steel sheet AC magnetic properties precision measuring instrument is used to measure the magnetic properties of low-temperature oriented silicon steel products.The research results show that when the cold rolling reduction rate is 91.7%,decarburization annealing 855?+120s,nitriding treatment 855?+50s,the best magnetic properties of the finished product can be obtained:B₈₀₀=1.837T,P_17/50=1.204W/kg.The study on the texture evolution law of each preparation process stage shows that the main texture types of cold rolling are mainly?texture,?texture and brass texture;after the initial recrystallization(decarburization,nitriding),?texture texture The texture is weakened,and the main texture types are{114}<418>,{111}<112>textures,{112}<110>textures,and brass textures.The micro-texture analysis of each process section after decarburization annealing shows that the cold rolling reduction rate is 91.7%and the nitriding treatment for 50s,the brass texture component of the test material is the lowest,and Goss is the first recrystallization structure It is not easy to be retained when there are few crystal grains.Moreover,the favorable grain boundary?9 and?13b have higher reduction rates than other grain boundaries,1.04%and 0.42%,respectively,which is conducive to abnormal growth of Goss grains during the secondary recrystallization process.The micro-texture statistics of the finished product In the results,the Goss texture accounted for 94.7%.