Influence of phase composition on Portevin-Le Chatelier effect in Al-Mg alloys

The temperature-strain rate domain of the Portevin-Le Chatelier (PLC) effect has been determined for three ultrafine grained aluminum alloys: Al-3Mg (А1), Al-4,57Mg0,35Mn-0,2Sc-0,09Zr (А2) and Al-5,4Mg-0,52Mn-0,1Zr (А3) (wt.%). The apparent activation energy of the serrated yielding was estimated. It was found that the presence of dispersed particles leads to a decrease in the activation energy and the temperature–strain rate domain of the PLC effect becomes narrowe

Hall-petch relationship in an Al-Mg-Sc alloy subjected to ECAP

Effect of extensive grain refinement on mechanical properties of an Al-Mg-Sc alloy subjected to equal-channel angular pressing (ECAP) at 300°C is considered in detail. It was shown that the Hall-Petch relationship with the coefficient, ky, of 0.2 MPa×m1/2 is valid in a wide strain range despite a great difference in deformation structures. Volume fraction of fine grains with an average size of ~1 μm gradually increases with strain. It is caused by the fact that additive contributions of grain size strengthening and dislocation strengthening to the overall strengthening take place in this alloy. Upon ECAP the extensive grain refinement is accompanied by increasing dislocation densit

The dynamic recrystallization behavior in Al-Mg alloys

The influence of phase composition on the behavior of dynamic recrystallization in alloys Al-3Mg (А1), Al-4.57Mg-0.35Mn-0.2Sc-0.09Zr (А2) and Al-5.4Mg-0.52Mn-0.1Zr (А3) (wt.%) during the equal-channel angular pressing (ECAP) was studied. The ECAP processing of alloy A1 resulted in a partially recrystallized microstructure with the mean size of coarse and fine grains of 20 and 1.4 μm, respectively In contrast, the formation of fully-recrystallized microstructure was observed in the alloys A2 and A

Interrelation between the Portevin Le-Chatelier effect and necking in AlMg alloys

Plastic flow instability caused by the Portevin Le-Chatelier (PLC) effect and its influence on the necking instability were studied in a binary and a precipitation-strengthened AlMg alloy using the digital image correlation (DIC) technique. Coarse-grained structure and two different finegrained states distinctly distinguished by dislocation density were produced in both alloys using similar routes of thermomechanical processin

Portevin-Le Chatelier effect in austenitic steel Fe-18%Cr- 8%Ni

The study of the mechanical behavior of the austenitic Fe-18% Cr-8% Ni steel was carried out in the temperature range of 530°C - 680°C at a strain rate of 1×10-3 s-1, as well as at a temperature of 620°C and strain rates of 1×10-2 s-1 - 1×10-4 s-1. At these conditions, the PLC effect was observed. Type A serrations were observed in the temperature range 530 - 680°С. A decrease in the strain rate at a temperature of 620°C leads to a change in the type of serrations from type A to type

Microstructural evolution of the AlMgMnZr alloy during severe plastic deformation

The effect of severe plastic deformation (SPD) on microstructure of Al-5.4Mg-0.52Mn-0.1Zr alloy was studied. The methods of equal channel angular pressing (ECAP) and cold rolling were used to obtain fine-grained microstructure. The evolution of average misorientation angle and portion of HAB during SPD was determined. The lattice dislocation density was evaluated from EBSD data from the lattice curvature using the via Frank's equatio

On the mechanisms of nucleation and subsequent development of the PLC bands in an AlMg alloy

The nucleation and subsequent development of the Portevin-Le Chatelier bands during tensile deformation in a binary AlMg alloy was investigated by the digital image correlation technique. The following states of the material were employed for the current investigation: coarse-grained (CG), fine-grained (FG) after equal channel angular pressing (ECAP), severely strained (SS) after ECAP followed by cold rolling. Special attention was paid to the nucleation of an embryo band by maximizing the contrast of the deformation image

Characterization of the spatiotemporal behavior of the PLC bands in austenitic steel during deformation at elevated temperature

The digital image correlation technique was used in situ during tensile testing to investigate the behavior of the Portevin-Le Chatelier (PLC) bands in a Fe-18Cr-8Ni-2.8Cu austenitic steel at a temperature of 680◦C. Effect of the strain on characteristics of the PLC bands, namely velocity, its intensity and the distance propagated by the bands was studied. New data of the spatiotemporal behavior of the PLC bands at elevated temperature were obtaine

Characterization of deformation-induced martensite with various AGSs upon Charpy impact loading and correlation with transformation mechanisms

Deformation-induced martensitic transformation (DIMT) during quasi-static loading has drawn much attention in recent years since it is considered as one of the key strengthening mechanisms in advanced high-strength steels (AHSS). However, systematic investigations on martensitic transformation at high strain-rates are scarce due to difficulties in experimental design