Quasi-in-situ Analysis Of The Recrystallization Of Deformed Metals

After plastic processing of metal parts,recrystallization annealing is often required to eliminate deformation hardening to obtain uniform equiaxed grains and good overall performance.The recrystallization of deformed metals is an important physical metallurgy phenomenon of metal materials.Due to its important role in the organization and properties,it has received extensive attention and in-depth research.However,the changes in the microstructure of the recrystallization process are complex and still need further clarification.The mechanism of crystal orientation evolution in the process of recrystallization of deformed metals is a difficult and key point in the study.The texture of ferritic stainless steel has a great influence on the forming performance,and the influence of the grain boundary structure of Hastelloy C-276 on performance is also very large.Therefore,a series of experiments were carried out for the recrystallization process of the two materials.The evolution mechanism of the crystal orientation of the ferritic stainless steel and the evolution of the grain boundary structure of the Hastelloy C-276 were investigated.The quasi-in-situ observation method was designed to analyze the recrystallization process of super ferritic stainless steel and finally got the following conclusion.(1)By observing the optical micrographs and counting the recrystallization ratio,The kinetic JMAK equation of super ferritic stainless steel at 700°C was fitted.(2)The recrystallization process was tracked by electron backscatter diffraction(EBSD),the orientation relationship between the deformed matrix and the recrystallized crystal nucleus,and the orientation change during recrystallization nucleus growth was observed and analyzed continuously.It is found that the nucleation in the shear zone is less than the grain boundary nucleation when the static recrystallization nucleation occurs,which is different from the previous researcher's view that the contribution of the intracrystalline shear band and the grain boundary to the nucleation is equivalent.(3)By quasi-in-situ observation of the orientation relationship between the deformed matrix and the recrystallized nucleus,it is presumed that the formation of the recrystallized texture of the cold-rolled ferritic stainless steel is more likely to be affected by the selective growth mechanism.Meanwhile,this research designed a cold rolling and annealing experiment on Hastelloy C-276,and then analyzed with EBSD.It was found that when the recrystallization is not completed completely,the increase in annealing twins leads to an increase in the special grain boundary of lanthanum 3 and the <101> orientation in the deformed structure as the holding time increases.It is the crystal orientation which is the most difficult to recrystallize,and the presence of this oriented crystal makes the completion of recrystallization very slow.