Study On Evolution Of Microstructure, Texture And Inhibitor In Grain-Oriented Silicon Steel Based On Strip Casting

Grain-oriented silicon steels (GO) having the preferred crystallographic{110} <001> texture, are widely used as core material of transformers because of low iron loss and high induction along the rolling direction. Currently industrial GO products are mainly produced by conventional process in which the slab were reheated high temperature up to 1400℃ and the Hi-B products were outputted by low temperature process in which the slab reheating less than 1300℃.Both the conventional process and low temperature slab reheating method have shortages on the magnetism of products and meanwhile these processes are too complex.Twin-roll stip casting technology has a short process, near-net-shape characteristics, is very suitable for the preparation of oriented silicon steel. Obtain stable and effective inhibitors and solve cold plastic poor, brittleness problem is to achieve higher grain oriented silicon steel strip casting products precondition, but oriented silicon steel strip casting preparation process and organizational characteristics of the study has been reported rarely.This paper have produced many strips with 3.0-4.0mm using the MnS as inhibitor by twin-roll strip casting which was the most innovation. We have designed a one-step cold rolling manufacturing process for the strips with fine equiaxed grains and a two-step cold rolling process for the strips with coarse columnar grains. The product thickness was0.27mm and 0.23mm respectively, the magnetic induction (Bs) is 1.94T and 1.84T respectively.Goss grains originated in the cast strip in one-stage cold rolling process, cold rolling texture composed strong a fiber texture with{112}<110> as the peak and weak y fiber texture with{111}<110> as the peak after cold rolling with a large reduction. Both a fiber texture and y fiber texture weaked after decarburization annealing and y fiber texture located in{111}<112> component which was very beneficial for secondary recrystallization.The first cold rolling texture consisted of strong a fiber texture and weak y fiber texture although the strips characterized by intense{001}<0vw> texture in the two-step cold rolling process. The y fiber texture increased gradually meanwhile a fiber texture decreased after intermediate annealing. After decarburization annealing, y fiber texture with{111}<110> and{111}<112> became the main components, yet a fiber texture almost disappeared full.The primary recrystallized grain size could be controlled at 13.9μm in one-step cold rolling method with fine equiaxed casting strips; simultaneously the primary recrystallized grain size size in two-step cold rolling method with coarse columnar grain structure can be controlled at 10.3μm.Few coarse MnTiS precipitates were found in the strip due to rapid cooling in strip casting and particularly a large number of MnS precipitates primarily precipitated at both dislocations and gains boundary during hot rolling as well as normalizing annealing followed by. Size of MnS precipitates were 30-50 nm dispersed in the steel and inhibited grain growth in the decarburization annealing.Asynchronous hot rolling could significantly refine grains while eliminated unfavorable{001}<0vw> texture in hot band. Intense shear deformations resulting from asynchronous hot rolling enhanced the Goss texture, and make the Goss grains deep into the central portion.In this paper, high magnetic induction grain-oriented silicon steel with 0.27mm and conventional grain-oriented silicon steel with 0.23mm were successfully produced, while providing microstructure, texture&precipitates and other relevant data. The research results could promote in-depth research and industrial production in future, and could contribute to the formation of independent intellectual property core technology of strip casting.