Anisotropic Electroplastic Effects on the Mechanical Properties of a Nano-Lamellar Austenitic Stainless Steel

Effects of electropulsing treatment(EPT)on the microstructural evolution and mechanical properties of a cold-rolled 316 L austenitic stainless steel with nano-lamellar structure were investigated.The EPT experiments were carried out with the electric current direction along the rolling direction(RD)and the transverse direction(TD)of the samples,respectively.Significant anisotropic electroplastic effects for the RD and TD specimens,i.e.,reduced hardness/strength and enhanced ductility,were obtained owing to the different recrystallization behaviors of the RD and TD specimens during EPT.The RD specimens after EPT with larger recrystallized grain size and higher volume fraction of recrystallization show lower strength and higher elongation than that of the TD specimens.The main reason might be attributed to the change of the current direction in the two kinds of samples,which results in the different sensitivity of the microstructures to thermal and athermal effects during EPT.

Features of Electroplastic Effect in Alloys with Martensite Transformation

Influence of different electric current modes （pulse and direct） on occurrence of the electroplastic effect under uniaxialtension in the coarse-grained alloys with martensite transformations is investigated. The materials are shape memoryTi49.3Niso.7 alloy and metastable austenite transformation-induced plasticity （TRIP） steel. The paper contains experimentalresults of current impact on the ＂stress-strain＂ curves of the material. It has been taken an experimental measurement ofthe sample temperature during the test. It is shown that the shape of a stress-strain curves and type of the serrate plasticflow, connected with the martensitic transformation and electroplastic effect, depend on the current modes. Impact of pulsecurrent and direct current suppresses shape memory and TRIP effect.

Electroplastic Tensile Behavior of 5A90 Al–Li Alloys

The electroplastic（EP） tensile properties of 5A90 Al–Li alloys compared with thermal tension were investigated.The microstructural variation at different conditions was observed by SEM and TEM.The current density significantly influences the elongation and the flow stress.With increasing current density,wider and deeper dimples on the fracture surfaces and less dislocation density and pile-ups in the EP tension samples were observed compared with roomtemperature and thermal tension,which indicates the plasticity improvement and flow stress reduction.The EP effect（EPE） mainly results from a comprehensive function of Joule heating and pure EPE.Among them,Joule heating effect is perhaps a dominant factor.

Experimental Investigation on Formability of AZ31B Magnesium Alloy V-Bending Under Pulse Current

In this work, the influence of pulse current parameters on springback and bending force of magnesium alloy duringelectropulse-assisted （EPA） V-bending was investigated. The experimental results showed that pulse current can effec-tively reduce the springback and the bending force compared to the experiments without current. The frequency has a moresignificant influence on bending force and springback than electric current density. Electroplastic （EP） effect begins towork when pulse current parameters reach a threshold value. To explore the mechanism of EPA V-bending, themicrostructure evolution and fracture surface of the bending specimen were studied. It was found that pulse current canpromote the occurrence of dynamic recrystallization （DRX） of magnesium alloy compared to traditional hot formingprocess. The fracture mode of AZ31B under EPA V-bending evolves from brittle fracture to ductile fracture withincreasing pulse current parameters. Based on the discussion of athermal and thermal effects of EP effect, the mechanismof pulse current to promote DRX is studied and athermal effect is proved to exist.