Early Strain Localization in Strong Work Hardening Aluminum Alloy (2198 T3): 3D Laminography and DVC Measurement

Author(s):  
Ante Buljac ◽  
Lukas Helfen ◽  
François Hild ◽  
Thilo F. Morgeneyer
2021 ◽  
pp. 22-30
Author(s):  
S. A Barannikova ◽  
A. M Nikonova ◽  
S. V Kolosov

This work deals with studying staging and macroscopic strain localization in austenitic stainless steel 12Kh18N9T within a temperature range of 143 K < T < 420 K. The visualization and evolution of macroscopic localized plastic deformation bands at different stages of work hardening were carried out by the method of the double-exposure speckle photography (DESP), which allows registering displacement fields with a high accuracy by tracing changes on the surface of the material under study and then comparing the specklograms recorded during uniaxial tension. The shape of the tensile curves σ(ε) undergoes a significant change with a decreasing temperature due to the γ-α'-phase transformation induced by plastic deformation. The processing of the deformation curves of the steel samples made it possible to distinguish the following stages of strain hardening, i.e. the stage of linear hardening and jerky flow stage. A comparative analysis of the design diagrams (with the introduction of additional parameters of the Ludwigson equation) and experimental diagrams of tension of steel 12Kh18N9T for different temperatures is carried out. The analysis of local strains distributions showed that at the stage of linear work hardening, a mobile system of plastic strain localization centers is observed. The temperature dependence of the parameters of plastic deformation localization at the stages of linear work hardening has been established. Unlike the linear hardening, the jerky flow possesses the propagation of single plastic strain fronts that occur one after another through the sample due to the γ-α' phase transition and the Portevin-Le Chatelier effect. It was found that at the jerky flow stage, which is the final stage before the destruction of the sample, the centers of deformation localization do not merge, leading to the neck formation.


2014 ◽  
Author(s):  
Ruslan R. Balokhonov ◽  
Eugen A. Schwab ◽  
Varvara A. Romanova ◽  
Aleksandr V. Zinoviev ◽  
Sergey A. Martynov

2015 ◽  
Vol 34 (7) ◽  
pp. 643-650
Author(s):  
Guo-zheng Quan ◽  
Jin Liu ◽  
An Mao ◽  
Bo Liu ◽  
Jin-sheng Zhang

Abstract The deep understanding of flow behaviors of as-extruded 7050 aluminum alloy significantly contributes to the accuracy simulation for its various plastic forming processes. In order to obtain the improved Arrhenius-type equation with variable parameters for this alloy, a series of compression tests were performed at temperatures of 573 K, 623 K, 673 K, 723 K and strain rates of 0.01 s−1, 0.1 s−1, 1 s−1, 10 s−1 with a height reduction of 60% on Gleeble-1500 thermo-mechanical simulator. It is obvious that strain rate, strain and temperature all have a significant effect on the hot flow behaviors, and the true stress–true strain curves indicate three types after the peak value: decreasing gradually to a steady state with sustaining DRX softening till a balance with work hardening, decreasing continuously with sustaining increasing DRX softening beyond work hardening and maintaining higher stress level after the peak value with a balance between work hardening and DRV softening. Based on the experimental data, the improved Arrhenius-type constitutive model was established to predict the high temperature flow stress of as-extruded 7050 aluminum alloy. The accuracy and reliability of the improved Arrhenius-type model were further evaluated in terms of the correlation coefficient (R), here 0.98428, the average absolute relative error (AARE), here 3.5%. The results indicate that the improved Arrhenius-type constitutive model presents a good predictable ability.


2013 ◽  
Vol 589-590 ◽  
pp. 117-121 ◽  
Author(s):  
Xiu Li Fu ◽  
Zeng Hui An ◽  
Yang Qiao ◽  
Xiu Hua Men

Work-hardening of machined surface plays an important role in the evaluation of surface quality and performance of wear resistance in the process of machining components. In this study work-hardening of machined surface during milling 7050-T7451 aluminum alloy is investigated using micro-hardness experiments under different cutting conditions. Moreover, the wear resistance of machined surface including wear quantity and friction coefficient are obtained and studied by means of high speed ring-block friction-wear tester. The work-hardening and wear resistance are particularly sensitive to cutting speed. Friction coefficient has marked drop trends and the tendency of wear quantity is ascend in first and descend at last as work-hardening increases. The comparison of wear resistance under different cutting conditions shows that the wear resistance of machined surface can be directly affected by work-hardening and machined surface obtained by high speed milling with higher micro-hardness have more superior in wear resistance performance.


2016 ◽  
Vol 655 ◽  
pp. 212-220 ◽  
Author(s):  
G.M. Owolabi ◽  
D.T. Bolling ◽  
A.A. Tiamiyu ◽  
R. Abu ◽  
A.G. Odeshi ◽  
...  

2020 ◽  
Vol 6 (12) ◽  
pp. 1265i2 ◽  
Author(s):  
Martin Ferreira Fernandes ◽  
Marcelo Augusto Santos Torres ◽  
Maria da Penha Cindra Fonseca ◽  
Carlos Antonio Reis Pereira Baptista

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