Anisotropic mechanical and acoustic emission behavior of A533B steels

Abstract

Acoustic emission characteristics of ASTM A533B steels were determined during tensile and fracture testing. Two different heats of thick plates were employed, and the orientation dependence of acoustic emission and mechanical behavior were studied in tensile tests and slow bend Charpy fracture tests. The types of acoustic emission signals, acoustic emission event counts, signal levels and amplitude distribution analysis were investigated. Three distinct types of acoustic emission signals were identified. One is the continuous type due to plastic deformation of the ferrite matrix. Two others are burst emissions, one of which has the characteristic Weibull function as its amplitude distribution and is attributed to the debonding of manganese sulfide inclusions. The other has a power law amplitude distribution which has often been reported in the literature. The exact origin(s) of this emission need(s) to be clarified. In this paper we describe a detailed study establishing the inclusion debonding to be the primary source of acoustic emission during the ductile fracture of A533B steels. This study further suggests that most burst-type acoustic emission in typical structural steels results from non-metallic inclusions in these materials.