Study On The Effect Of Cooling Rate On Solidification Structure And Segregation Behavior Of 40Cr Steel

In continuous casting,thermal conductivity of steel affects the segregation behavior of slab,in the same time,solidification structure of slab and distribution of alloy elements affect thermal conductivity of steel.Studying on the influence of different cooling rates on solidification structure of chromium steel can provide a basis for further research on correlation between solidification structure and thermal conductivity of chromium steel.It also can provide the theoretical foundation of optimizing cooling schedule optimization of the continuous casting process in chromium steel.For these purpose,through thermal simulation experiment,chemical analysis and energy spectrum analysis,this paper has analyzed the influence of cooling rate on solidification structure of 40 Cr steel,grain size,macrosegregation and microsegregation of chromium(Cr).The main conclusions of this paper can be concluded as follows:(1)Under the condition of natural cooling,the solidification structures of 40 Cr steel are all equiaxed grains.The Edge and top of steel sample have many fine equiaxed grains.In condition of argon blowing,coarse columnar crystal appeared in solidification structure of steel sample.With the further increasing of argon blowing,shrinkage in casting slab become bigger.Solidification structure trend to be typical three layers solidification structure.(2)With the increasing of the initial cooling temperature of liquid steel,solidification structure of 40 Cr steel has coarsening behavior and the grian size is enlarged.(3)Under the condition of the experiment,the gathering phenomena of pearlite appears in the edge and intragranular of steel sample.(4)In all equiaxed grain,from the surface to the center,the phenomenon of the concentration of alloying element in surface is low and in center is high which exist in typical three layers' solidification structure not appears.(5)Under the condition of natural cooling,in the course of the cooling rate increases,microsegregation ratio of Cr in surface of sample goes down,the middle and central microsegregation ratios are no significant change.With the increasing of argon blowing rate,the surface,middle and central microsegregation ratios increase.(6)The starting cooling temperature affects microsegregation ratios of Cr.When the starting cooling temperature is 1550?,in the half-height cross section of steel sample,the microsegregation ratios of Cr is little bigger than which is under 1560? and 1570?.