Study on critical damage factor and the constitutive model including dynamic recrystallization softening of AZ80 magnesium alloy

• Published in: Science of sintering 2013, Vol.45 (2), p.199-208
• Main Authors: Xue, Y., Zhang, Z.M., Wu, Y.J.
• Format: Article
• Language: English
• Subjects: AZ80 magnesium alloy; constitutive model; critical damage factor; dynamic recrystallization; strain softening
• ISSN: 0350-820X; 1820-7413
• DOI: 10.2298/SOS1302199X

Quantities AZ80 magnesium alloy billets were compressed with 60 % height reduction on hot process simulator at 473, 523, 573, 623, 673, 723 K under strain rates of 0.001, 0.01, 0.1, 1 and 10 s-1. In order to predict the occurrence of surface fracture, the critical damage factor based on the Cockcroft-Latham equation were obtained by analysing the results of the corresponding finite element calculation. The results show that the critical damage factor at 523, 573, 623, 673 K under strain rates of 0.001, 0.01, 0.1 and 1 s-1 is not a constant but varies in a range from 0.1397 to 0.4653. Meanwhile, a constitutive model with a few parameters is used to characterize the dynamic recrystallization strain softening of AZ80 alloy, which comprehensively reflect the effects of the deformation temperature, strain and strain rate on the flow stress. Poluge legure magnezijuma AZ80 presovane su sa 60 % redukcije na toplom procesnom simulatoru na 473, 523, 573, 623, 673, 723 K pri brzinama deformacije od 0,001; 0,01; 0,1;1 i 10 s-1. U cilju pracenja pojave preloma povrsine, kriticni faktor ostecenja baziran na Kokroft-Latamovoj jednacini odredjen je analizom rezultata koji korespondiraju sa obracunom konacnih elemenata. Rezultati pokazuju da kriticni faktor ostecenja na 523, 573, 623, 673 K pri brzinama deformacije od 0,001; 0,01; 0,1 i 1 s-1 nije konstantna vrednost vec varira u intervalu od 0,1397 do 0,4653. U medjuvremenu, upotrebljen je konstitutivni model sa nekoliko parametara za karakterizaciju dinamicke rekristalizacije slabljenja deformacija legure AZ80, koji sveobuhvatno odrazava efekte temperature deformacije, deformacije i brzine deformacije na protok stresa.