Analysis of the surface cracks and void closure of bloom during hot-core heavy reduction rolling
The hot-core heavy reduction process can eliminate the porosity and shrinkage defects in the core of the bloom,but the stress state of the bloom is complex and variable,and the fracture criterion in accordance with the heavy reduction deformation process is scarce,which restricts the industrial application of the hot-core heavy reduction process.The GCr15 bearing bloom was used as the object of study,the evolution paths of different stress states during material deformation were obtained by desig-ning special-shaped compression specimens to restore the complicated stress states during the heavy reduction of bloom,and then the surface crack criterion was established for the hot-core heavy rolling process.Combined with the numerical simulation,the risk of surface crack and the shape evolution of the void was analyzed by making a void in the core of the bloom.The results show that due to the temperature gradient along the thickness direction of the bloom,the larger reduction rate is,the more obvious im-provement effect on the core region defects is.When the reduction rate is 33.3％,the void in the core of bloom is completely closed.The surface damage value of the bloom is lower than the critical damage value,and thus no new surface cracks are generated.
hot-core heavy reduction rollingsurface crackvoid closurenumerical simulationGCr15 bloom
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