Microstructure Evolution Of 50W600 Cold Rolled Non-oriented Siliconsteel During Batch Annealing Based On CSP Process

As a kind of soft magnetic alloy with excellent properties,non-oriented electrical steel is widely used in electric power,electronics,military and magnetic materials.In recent years,the CSP process has been applied to the production of high value-added steel products.However,there is no report on the production of non-oriented electrical steel based on thin slab continuous casting and rolling(CSP)process and batch-type annealing process.The study of microstructure of non-oriented Electrical Steel based on CSP process during batch-type annealing is of great practical significance to extend the hot rolled products from thin slab continuous casting and rolling process to high-end products in China.In this paper,50W600 non-oriented silicon steel ingots with different silicon contents of 1.6% and 1.4% were smelted in laboratory.Two kinds of cold rolled base materials were obtained by hot rolling,coiling and cold rolling with Compact Strip Production process.Two annealing processes of non-oriented electrical steel,hot spot status and cold spot status,were simulated in a box furnace in the laboratory.ZZeiss optical microscope,X-ray diffraction(XRD),scanning electron microscope(SEM)and transmission electron microscope(TEM)were used to observe the microstructure,texture and second phase of the batch annealed samples,and electron back scattering diffraction(EBSD)was used to observe the grain orientation of different parts of the thickness direction of the samples.The experimental steels with different silicon content begin to recrystallize at 520 ?and complete recrystallization at 590 ?.The average grain size of the two steels is 50?m at the end of the hot spot heating stage The average grain size is 100?m when the batch annealing is completed.At the end of heating stage,the average grain size is 57 ?m.However,the average grain size is 97 ?m.It is slightly smaller than the hot spot.0.12% Si content has little effect on the grain size of non oriented electrical steel during batch type annealing.After batch annealing,the average grain size of the hot spot steel with faster heating rate and longer holding time is slightly larger than that of the cold spot steel;The annealing process of experimental steel is accompanied by ? The texture strength of orientation line decreases,? The texture strength of orientation line increases,? The orientation line texture increases.The results show that the main textures of the finished sheet with different silicon content are {111} <112> and {111} <110>;The results show that the precipitates are mainly tic and Al N after batch type annealing.The surface density of precipitates is slightly lower in the experimental steel with higher silicon content,and the size of precipitates in hot spot is larger than that in cold spot.The second phase size of non oriented electrical steel after annealing is small,but its area density is low,and its effect on grain boundary pinning is weak.This makes the average grain size of the finished plate reach 100 ?m.The new {111} <112> grains nucleate in the deformed {111} <110>grains and the new {111} <110> grains nucleate in the deformed {111} <112> grains at the initial stage of recrystallization in the cold and hot spots of batch type annealing of non oriented electrical steel.It is proved that the nucleation mode of batch type annealing is directional nucleation,i.e ?-{111} texture nucleate first and grow rapidly,swallowing the grains with other orientations.From the above experimental results,it can be seen that there is no significant difference in the average grain size of the finished product in the hot and cold spot state of the non-oriented electrical steel during the bell annealing process,both are 100?m;the main textures are both {111}<112> and { 111}<110> and the peak intensity is similar;the average particle size and distribution density of the second phase also have no significant difference.Therefore,the different heating states of the non-oriented electrical steel during the cover annealing process have no obvious effect on its grain size,texture and second phase.Its grain size,texture type,and size and distribution of precipitated phases are basically the same as those of the traditional process.Consistent,so it is feasible to produce non-oriented electrical steel based on the CSP process and the bell annealing process.