TY - JOUR

T1 - Hot deformation behavior of Mg-2Sn-2Ca alloy in as-cast condition and after homogenization

AU - Rao, K. P.

AU - Prasad, Y. V.R.K.

AU - Suresh, K.

AU - Hort, N.

AU - Kainer, K. U.

PY - 2012/8/30

Y1 - 2012/8/30

N2 - The hot deformation behavior of Mg-2Sn-2Ca (TX22) alloy has been characterized in the temperature range 300-500°C and strain rate range 0.0003-10s-1 using isothermal constant true strain rate tests. A processing map has been developed on the basis of flow stress data obtained as a function of temperature and strain rate, which revealed two windows or domains for hot working the alloy: (1) 300-370°C/0.0003-0.001s-1 and (2) 400-500°C/0.005-1s-1. Microstructural observations indicated that dynamic recrystallization occurs in both these windows with a finer resulting grain size in the first window. Apparent activation energy values of 183 and 178kJ/mole have been estimated in these windows, respectively and these are much higher than that for self-diffusion in Mg suggesting that considerable back stress is being generated due to the intermetallic particles (CaMgSn) present in the matrix. The mechanisms involving basal+prismatic slip and recovery by climb in the first domain and that of second order pyramidal slip and softening by cross-slip in the second domain are suggested to be occurring in these two domains. The processing map obtained on homogenized alloy is identical to that of the as-cast alloy suggesting that there is no benefit of homogenization treatment as regards hot workability and this is attributed to the thermal stability of the as-cast microstructure.

AB - The hot deformation behavior of Mg-2Sn-2Ca (TX22) alloy has been characterized in the temperature range 300-500°C and strain rate range 0.0003-10s-1 using isothermal constant true strain rate tests. A processing map has been developed on the basis of flow stress data obtained as a function of temperature and strain rate, which revealed two windows or domains for hot working the alloy: (1) 300-370°C/0.0003-0.001s-1 and (2) 400-500°C/0.005-1s-1. Microstructural observations indicated that dynamic recrystallization occurs in both these windows with a finer resulting grain size in the first window. Apparent activation energy values of 183 and 178kJ/mole have been estimated in these windows, respectively and these are much higher than that for self-diffusion in Mg suggesting that considerable back stress is being generated due to the intermetallic particles (CaMgSn) present in the matrix. The mechanisms involving basal+prismatic slip and recovery by climb in the first domain and that of second order pyramidal slip and softening by cross-slip in the second domain are suggested to be occurring in these two domains. The processing map obtained on homogenized alloy is identical to that of the as-cast alloy suggesting that there is no benefit of homogenization treatment as regards hot workability and this is attributed to the thermal stability of the as-cast microstructure.

KW - Dynamic recrystallization

KW - Hot deformation

KW - Magnesium alloy

KW - Plastic behavior

KW - Processing maps

KW - Engineering

UR - http://www.scopus.com/inward/record.url?scp=84862981402&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/0361f995-beae-3ba6-9b9b-4a07ac3ea696/

U2 - 10.1016/j.msea.2012.05.068

DO - 10.1016/j.msea.2012.05.068

M3 - Journal articles

AN - SCOPUS:84862981402

VL - 552

SP - 444

EP - 450

JO - Materials Science and Engineering A

JF - Materials Science and Engineering A

SN - 0921-5093

ER -