TY - JOUR

T1 - Optimization of thermo-mechanical processing for forging of newly developed creep-resistant magnesium alloy ABAX633

AU - Pitcheswara Rao, Kamineni

AU - Dharmendra, Chalasani

AU - Venkata Rama Krishna Prasad, Yellapregada

AU - Hort, Norbert

AU - Dieringa, Hajo

PY - 2017/11/21

Y1 - 2017/11/21

N2 - The compressive strength and creep resistance of cast Mg-6Al-3Ba-3Ca (ABaX633) alloy has been measured in the temperature range of 25 to 250 ℃, and compared with that of its predecessor ABaX422. The alloy is stronger and more creep-resistant than ABaX422, and exhibits only a small decrease of yield stress with temperature. The higher strength of ABaX633 is attributed to a larger volume fraction of intermetallic particles (Al, Mg)2Ca and Mg21Al3Ba2 in its microstructure. Hot deformation mechanisms in ABaX633 have been characterized by developing a processing map in the temperature and strain rate ranges of 300 to 500 ℃ and 0.0003 to 10 s−1. The processing map exhibits two workability domains in the temperature and strain rate ranges of: (1) 380 to 475 ℃ and 0.0003 to 0.003 s−1, and (2) 480–500 ℃ and 0.003 to 0.5 s−1. The apparent activation energy values estimated in the above two domains (204 and 216 kJ/mol) are higher than that for lattice self-diffusion of Mg, which is attributed to the large back-stress that is caused by the intermetallic particles. Optimum condition for bulk working is 500 ℃ and 0.01 s−1 at which hot workability will be maximum. Flow instability is exhibited at lower temperatures and higher strain rates, as well as at higher temperatures and higher strain rates. The predictions of the processing map on the workability domains, as well as the instability regimes are fully validated by the forging of a rib-web (cup) shaped component under optimized conditions.

AB - The compressive strength and creep resistance of cast Mg-6Al-3Ba-3Ca (ABaX633) alloy has been measured in the temperature range of 25 to 250 ℃, and compared with that of its predecessor ABaX422. The alloy is stronger and more creep-resistant than ABaX422, and exhibits only a small decrease of yield stress with temperature. The higher strength of ABaX633 is attributed to a larger volume fraction of intermetallic particles (Al, Mg)2Ca and Mg21Al3Ba2 in its microstructure. Hot deformation mechanisms in ABaX633 have been characterized by developing a processing map in the temperature and strain rate ranges of 300 to 500 ℃ and 0.0003 to 10 s−1. The processing map exhibits two workability domains in the temperature and strain rate ranges of: (1) 380 to 475 ℃ and 0.0003 to 0.003 s−1, and (2) 480–500 ℃ and 0.003 to 0.5 s−1. The apparent activation energy values estimated in the above two domains (204 and 216 kJ/mol) are higher than that for lattice self-diffusion of Mg, which is attributed to the large back-stress that is caused by the intermetallic particles. Optimum condition for bulk working is 500 ℃ and 0.01 s−1 at which hot workability will be maximum. Flow instability is exhibited at lower temperatures and higher strain rates, as well as at higher temperatures and higher strain rates. The predictions of the processing map on the workability domains, as well as the instability regimes are fully validated by the forging of a rib-web (cup) shaped component under optimized conditions.

KW - Compressive strength

KW - Hot forging

KW - Hot workability

KW - Magnesium alloy

KW - Processing map

KW - Engineering

UR - http://www.scopus.com/inward/record.url?scp=85035352054&partnerID=8YFLogxK

U2 - 10.3390/met7110513

DO - 10.3390/met7110513

M3 - Journal articles

AN - SCOPUS:85035352054

VL - 7

JO - Metals

JF - Metals

SN - 2075-4701

IS - 11

M1 - 513

ER -