The Effects Of Nb On The Precipitation Behaviors Of The Inhabitors In The Grain-oriented Silicon Steel During Hot Rolling

Hi-B oriented silicon steel is a kind of high performance silicon steel sheet,it has low iron loss,high magnetic induction strength is generally used in the field of ultra high pressure.Because of MnS+Al N as inhibitors of traditional Hi-B steel by high temperature slab heating technology,resulting in low product yield and manufacturing cost higher shortcomings,in order to realize low temperature slab reheating oriented silicon steel,the second phase particles of other scholars both at home and abroad as inhibitors of feasibility study,it is also a new focus in the research and development of steel industry at present.This article in view of the different content of Nb,Als Sn containing silicon steel,the thermodynamic calculation software study Nb content on Nb deposition of solid solution:precipitation,pilot production are adopted to simulate the low temperature rolling process,and the cross section of the product organization,the distribution of the hot rolled texture and the analysis of precipitates were observed.In order to verify the thermodynamic law of Nb second phase particle precipitation.The main contents of the study are as follows:（1）The formation mechanism of precipitates in oriented silicon steel and the total solid solution temperature of precipitates were analyzed by thermodynamic calculation.Nb（C,N）solid solution temperature is 1227℃,AlN in solid solution temperature is1094℃,MnS in solid solution temperature is 1158℃,Si₃N₄ in solid solution temperature is 846℃,can obtain the steel to a certain extent,can satisfy the requirement of 1250℃low temperature oriented silicon steel to inhibitors.Using thermo-calc thermodynamic software,the samples were firstly precipitated out of Nb（C,N）,followed by MnS,then AlN and Si₃N₄ and then precipitated out,the relationship between the temperature of the equilibrium phase between the sample and the sample was Nb（C,N）>MnS>AlN>Si₃N₄.（2）The distribution of microstructure in Nb low-temperature-oriented silicon steel was studied by using pilot production simulation.Oriented silicon steel microstructure of hot rolled plate under the metallurgical microscope to see scattered in the thickness direction is uneven,the surface layer of fine grain structure,subsurface for the ferrite grain size slightly larger,central region is composed of relatively large deformation of grain,grain presents a strip,and the parallel to the rolling direction.The average grain size of the grain was measured,and when the content of Als was equal,the grain size of the hot rolled surface would become smaller with the increase of Nb content,and the grain size of the subsurface would become larger.As the content of the Nb increases,the size of the subsurface grain size will increase with the increase of Als content.（3）The characteristics and precipitate behavior of the precipitates in the hot-rolled plate of oriented silicon steel were observed.The morphology of the precipitates in nb-oriented silicon steel hot-rolled plate is mainly spherical,blocky and irregular,mainly composed of Nb（C,N）,MnS and AlN complexes.When the content of Als is at the same time,as the content of Nb increases,the size of the precipitate will become smaller,and the number of precipitates will increase.As the content of the Nb increases,as the content of Als increases,the size of the precipitates will become larger and the number of precipitates will decrease.（4）Distribution EBSD analysis of hot rolled texture in hot rolled plate of oriented silicon steel.When the content of Nb increases,the grain size of the second phase particle will become smaller,the volume fraction will be larger,and the inhibition force of the subsequent initial recrystallization grain will be larger.At low temperature 2#high Nb sample Goss texture{110}<001>will be higher and more accurate than 1#low Nb sample,and will produce more small dispersive auxiliary inhibitors and stronger gaussian texture.