Study On The Effects Mechanism Of Deformation Modes On The Microstructure And Corrosion Behavior Of 316L Stainless Steel

In this paper,the effects of two cold deformation modes(torsion/rolling)on the microstructure evolution of 316L stainless steel were investigated using X-ray diffraction(XRD)and electron backscatter diffraction(EBSD)techniques,and the influence of grain boundary engineering on the microstructure evolution as well as the distribution of special grain boundaries in the two cold deformation modes were studied.The corrosion resistance of the samples after grain boundary engineering(deformation+annealing)treatment was evaluated using oxalic acid electrolytic corrosion,HNO3-HF corrosion and electrochemical corrosion,and the mechanism of special grain boundaries to improve the intergranular corrosion performance was investigated.The microstructure evolution of 316L stainless steel was investigated by cold deformation in different deformation modes.It was found that the grain deformation in the torsion samples was heterogeneous,decreasing significantly from the edge to the center,and no martensitic transformation occurred during the deformation process.Unlike torsion,deformation-induced martensitic transformation have occurred in the samples when the reduction rate exceeded 10%during rolling.It was worth noting that significant dynamic recrystallization occurred during both torsion and rolling.The samples were annealed after deformation to study the effect of grain boundary engineering on the distribution of special grain boundaries of 316L stainless steel based on the two deformation modes.The results show that the grain boundary engineering in both deformation modes tailors the distribution of special grain boundaries inside the sample.In the samples subjected to torsion and annealing with different times,the content of ?CSL as well as ?3 grain boundaries first increased from 35.29%and 29.40%to 62.03%and 51.84%,respectively,and then decreased to 45.36% and 39.89%.Among them,the ?CSL and ?3 content of GBE-3 h sample was significantly higher than that of other samples.Through studying the samples with rolling and annealing,it was found that the samples with low deformation(5%in reduction)with high temperature annealing were more likely to obtain a high percentage of special grain boundaries ?CSL(63.4%)and ?3(57.0%).As the content of ?CSL and ?3 boundaries increases,the connectivity of the large-angle random grain boundary was interrupted more obviously.The effect of the distribution of special grain boundaries on the corrosion resistance of 316L stainless steel was investigated.It was found that the special grain boundaries mainly include ?3,?9 and ?27,but not all the special grain boundaries showed significant corrosion resistance,only ?3 showed excellent corrosion resistance,samples with a high proportion of special grain boundaries ?3 had stronger corrosion resistance than those with low ?3 content,and the corrosion resistance of random high-angle grain boundaries that stimulates ?3(twins)boundaries was also improved.