Evaluation of toughness characteristics of a die-cast Mg–Al–Mn alloy Am60B under different microstructural conditions

The fracture toughness characteristics of AM60B die-casting Mg–Al–Mn high purity alloy are reported. The material, combining rather good ductility, casting properties, and corrosion resistance, is used for manufacturing large thin-section components for the automotive industry. Center-cracked tension specimens of a thickness of 2.2–3.1 mm were machined directly from components produced on large scale and were tested both in as-die-cast and in aged (heat treated for 18 h at 175 °C) conditions, monitoring stable crack propagation under increasing applied load. Crack growth resistance curves (R-curves) were obtained, and the stress intensity factor leading to unstable crack propagation was found to be about 20 MPa m1/2 for the as-die-cast material and about 19 MPa m1/2 for the aged alloy.