Effect Of Rare Earth And High Temperature Annealing On Microstructure And Properties Of Oriented Silicon Steel

Oriented silicon steel is widely used in electronics,power and military industry.It is an indispensable soft magnetic material.Its manufacturing process is rigorous,complex,long process and high energy consumption,which represents the representative of a country's special steel manufacturing level.The addition of rare earth elements in iron and steel materials can purify and refine grains.Therefore,the addition of rare earth elements in iron and steel materials has become an important means to develop high quality rare earth microalloyed steel.For oriented silicon steel,the primary recrystallization annealing and high temperature annealing are important links in its production.Through these two links,the grain orientation of oriented silicon steel can be formed into a single Gauss grain orientation,and the oriented silicon steel has good magnetic properties.Therefore,it is of great theoretical and practical significance for the production of oriented silicon steel to explore the evolution of microstructure and micro-orientation in these two processes.In this paper,the primary recrystallization annealing and high temperature annealing process of oriented silicon steel hot rolled sheet containing copper and trace rare earth are studied.The primary and secondary factors affecting the decarburization effect of oriented silicon steel and the optimal primary recrystallization annealing process are found out by orthogonal test.The primary recrystallization and secondary recrystallization of oriented silicon steel are studied by metallographic microscope and scanning electron microscope.Microstructure evolution during secondary recrystallization.The results show that the optimum initial recrystallization annealing process is:temperature is 830?,atmosphere?N₂:H₂?is 3:1,time is 7 minutes.The order of influence of each factor on Decarburization effect of the initial recrystallization annealing is annealing atmosphere>annealing time>annealing temperature>rare earth elements.During the initial recrystallization annealing stage,the grain size of the samples containing rare earth elements is smaller than that of the samples without rare earth elements,and the structure is more homogeneous;after adding rare earth elements,the sum of the four propitious Gauss oriented grains{111}<112>,{111}<110>,{411}<148>,{012}<001>and the volume fraction of CSL grain boundaries??3,?5,?9?increase.The proportion of Gauss orientation is not high,and the orientation difference is mainly between 20 and 45 degrees,which is beneficial to the abnormal growth of Gauss grains during secondary recrystallization of oriented silicon steel.In the process of high temperature annealing,the starting time of secondary recrystallization of the samples without 3%,6%and 9%of REE is 900?,the starting time of secondary recrystallization of the samples with 9%of REE is 930?,the starting time of secondary recrystallization of the samples with 3%and 6%of REE is between 930?and 950?,and the second recrystallization occurs during the process of high temperature annealing.During secondary recrystallization,the proportion of CSL grain boundary decreases,and the proportion of medium deviation angle grain boundary decreases from 20 to 45 degrees.