Fatigue properties and toughness in flame-resistant magnesium alloys and influences of welding

Abstract

This study investigates the fatigue properties, Charpy impact energy, and fracture toughness of three flame-retardant magnesium alloys with the different amount of aluminum solid solution. These properties strongly depended on the amount of aluminum dissolved in the magnesium alloy. Micro-strain analysis was used to evaluate the degree of damage during fatigue tests. This method could successfully evaluate the degree of damage by focusing on the principal slip plane rather than the crystallographic planes. In addition, we examined the influence of welding, wherein AZX811 filler metals containing Ga were used, on Charpy impact energy and fracture toughness. The Charpy impact energy of the welded joint was lower than that of the base metal with the same amount of aluminum solid solution. However, the fracture toughness value of the welded joint was almost the same as that of the base metal. This was because the welding defects decreased the Charpy impact absorbed energy. However, they did not affect the fracture toughness value owing to the microscopic elastoplastic behavior of the crack tip. Furthermore, a proportional relationship between the impact-absorbed energy and fracture toughness value was determined for both the base metal and welds.