Relationship between Minimum Creep Rate and Rupture Life for a Die-Cast Mg-Al-Mn Alloy

Abstract

Creep rupture tests were performed for a die-cast Mg-Al-Mn alloy, AM50, at 34 kinds of creep conditions in the temperature range between 423 and 498 K. The creep curve is characterized by a minimum in the creep rate followed by an extended accelerating stage. The minimum creep rate (\\dotε_m) and the creep rupture life (t_rup) follow the phenomenological Monkman-Grant relationship; t_rup=C₀⁄\\dotε_m^m. It is found for the die-cast AM50 alloy that the exponent m is unity and the constant C₀ is 0.13, independent of creep testing temperature. The values of m and C₀ are compared with those for other die-cast magnesium alloys.