Study On Electroplastic Deformation Mechanism And Rolling Process Of 304 Stainless Steel Strip

304 stainless steel strip has excellent mechanical properties and surface quality,which can meet the manufacturing needs of key parts in many miniaturized products,and is widely used in many high-end fields.However,when the thickness of the thin strip reaches the micron level,the practical application puts forward very high requirements for its machining accuracy and production quality.At present,there are some problems in the production of 304 stainless steel strip by traditional cold rolling process,such as difficult plastic deformation,poor forming quality and so on.Pulse current can reduce the deformation resistance of materials and improve the ability of plastic deformation,which is called electroplastic effect(Electroplastic effect,EPE).The combination of electroplasticity and multi-roll rolling process is expected to improve the deformability and forming quality of stainless steel strip.In this paper,the tension and rolling process of 304 stainless steel strip assisted by pulse current were studied on the self-designed and modified test platform,and the evolution of mechanical properties and microstructure of 304 stainless steel strip under the action of pulse current were analyzed.the influence mechanism of pulse current on the plastic deformation mechanism of 304 stainless steel strip was explained,and the electroplastic rolling process was explored.The results of pulsed current-assisted tensile test showed that compared with conventional tension,electrified tension decreased the flow stress and fracture elongation of304 stainless steel strip at the same time,and the fracture mode of electrified tension changed from full dimple fracture to partial shear fracture.According to the microscopic analysis,it is found that the lattice distortion of austenite is weakened,the lattice constant of austenite is reduced,and chromium carbide is formed on the grain boundary on the surface of the sample due to the existence of pulse electric current.the plastic deformation mode of the sample changed obviously compared with the conventional tension,which was dominated by dislocation slip,while the twinning and martensitic transformation were suppressed,which is one of the main reasons for the early fracture of the sample.The existence of electric current promotes the low temperature recovery and recrystallization process of 304 stainless steel strip,but this microstructure evolution can not make up for the decrease of elongation caused by other mechanisms.According to the study of pulse current-assisted rolling process,it is found that compared with cold rolling,pulse current-assisted rolling process significantly reduces the tensile deformation resistance of rolled strip,reduces its yield strength,and increases its elongation at the same time,and the Vickers hardness of electrorolled ultra-thin strip is decreased.The main reason is that the martensitic transformation of 304 stainless steel strip is inhibited during electric rolling,which means that more retained austenite is retained in the strip after electrorolling,which contributes to more martensitic transformation in the subsequent drawing process,and the fracture of the rolled piece is delayed by TRIP effect.