Abstract
The simple method for evaluation of fracture toughness in Mg alloys was examined by AE. In this study, fracture toughness (KIAE) in AZ31 (Mg-9Al-1Zn), AZ91 (Mg-9Al-1Zn), and LA141 (Mg-14Li-1Al) was investigated. Specimens (L-S, T-S) were machined from as-rolled AZ31, LA141, and as-cast AZ91. Four-point-bending tests were conducted according to ASTM E-399 with AE measurement, and the crack pass was observed by microscope during the testing. KIC was supposed to be the value of KI when the crack initiates from the tip of the pre-crack. KIAE was defined as the value of KI when the RMS voltage of AE indicated the maximum value before ultimate load. The crack propagation was observed by microscope at the time of RMS peak. The values of KIAE were 12.4-15.0 (AZ31), 11.5-11.7 (AZ91), and 24.7-28.0 (LA141) [MPa m1/2]. Compared with reference data, the fracture toughness in Mg alloys estimated by KIAE was adequate. The possibility of the simple method for evaluation of fracture toughness in Mg alloys by AE was demonstrated.
