G. Tang

Study on electropulsing assisted turning process for AISI 304 stainless steel

Abstract Electropulsing was introduced into the turning process of the AISI 304 stainless steel. The results indicate that the main cutting force, microhardness and axial roughness on machined surface are reduced dramatically under appropriate electropulsing parameters. For AISI 304 stainless steel, the electropulsing applied in turning process can improve the plastic deformation ability in cutting area, increase lubricating property and change friction state between the tool and the workpiece in the forming process of the chip. It causes the arising of plastic stripping tear based on pure shear plastic deformation and brings obvious changes on morphologies of the machined surface and the corresponding chip.

Effects of electropulsing assisted ultrasonic impact treatment on welded components

Abstract The effect of electropulsing assisted ultrasonic impact treatment (EUIT) on the mechanical properties and microstructure evolution of S50C steel welded components has been investigated. The present paper presents the application of a relatively new post-weld treatment method to eliminate the residual stress and improve the surface mechanical properties. The results show that EUIT exhibits better surface modification capability than does conventional ultrasonic impact treatment. After EUIT, plastic deformation layer with strengthened grains formed on the sample surface, and residual tensile stress was converted into residual compressive stress.

Improvement of surface properties of 2316 stainless steel with ultrasonic electric surface modification

Abstract An ultrasonic electric surface modification treatment was employed to improve the surface properties of 2316 stainless steel. The surface properties of the specimens after conventional cutting, ultrasonic surface modification treatment and ultrasonic electric surface modification treatment were characterised respectively. A grain refinement layer was formed on the specimens surface after ultrasonic electric surface modification treatment. The average grain size on the top surface was refined into the submicrometre or nanometre scale. This is caused mainly by two aspects: one is the accumulation of initial tiny particles during deformation, and the other is that the ferrite is smashed into pieces due to microfatigue damage. Moreover, it was found out that the specimen after ultrasonic electric surface modification treatment at four times had shown the optimal surface properties.

Mg–3Al–1Zn alloy strips processed by electroplastic differential speed rolling

The effect of reduction per pass on the mechanical properties, microstructure and texture evolution of Mg–3Al–1Zn magnesium alloy strips processed by electroplastic differential speed rolling has been investigated. With increasing reduction per pass, the mechanical properties of the rolled strips increase. Both the shear effect and the current pulses play an important part in modifying the microstructure and texture by promoting dynamic recrystallisation. During dynamic recrystallisation, nucleus tends to nucleate in the vicinity of the shear bands. And as the progress of dynamic recrystallisation, shear bands are gradually consumed by the newly nucleated grains and become nearly indistinguishable. The athermal effect of current pulses plays an important role in promoting dynamic recrystallisation.

The improved plasticity of NiTi alloy via electropulsing in rolling

NiTi alloys were cold-rolled and electroplastic-rolled (EP-rolled) respectively, and the effect of rolling parameters on working plasticity was studied. NiTi alloy is easy to be embrittled and cracked in cold rolling, and the number of edge cracks is increased with higher thickness reduction. Electropulsing can enhance the ductility of NiTi alloy in rolling. In rolling, the resistance of deformation can be decreased, and deformation degree at the same roll gap increases because NiTi alloy develops recrystallisation and the hardness is decreased. GRAPHICAL ABSTRACT

Effect of electropulsing-assisted turning process on AISI 5120 cementation steel

ABSTRACT Electropulsing was used to aid in the cutting process of the AISI 5120 cementation steel. Electropulsing is found, on the one hand, to significantly decrease the main cutting force and reduce the tool wear and, on the other hand, to largely improve the surface quality and surface hardness of the specimen. Electropulsing showed remarkable improvement in plastic deformation ability and cutting properties by inducing lubrication property. This phenomenon can be explained by the enhanced mobility of dislocations that resulted from the electroplastic effect and Joule heating. This paper is part of a themed issue on Materials in External Fields.

Magnetic field induced twins in martensite and their effect on subsequent cementite precipitation in Fe–0.32 wt-%C steels

Abstract Magnetic field induced twins in martensite and their effect on the succedent cementite precipitation in Fe–0.32 wt-%C steels have been studied. Specimens were quenched with and without a magnetic field. In the martensite formed under the magnetic field, many twins were obtained, while few twins were found in the martensite formed without a magnetic field. When the specimens were subsequently tempered without a magnetic field, the magnetic field induced twins influenced the morphology of cementite precipitation. Owing to the effect of magnetic field induced twins and the change in morphology of cementites, the strength of the specimen quenched under magnetic field and tempered was considerably increased, while the tensile ductilities were slightly reduced at the same time.