Acoustic and magnetic methods for characterisation of microstructures and tensile deformation in AISI type 304 stainless steel

Microstructural characterisations with non-destructive test techniques is a relatively new and useful method of assessment of the quality of finished components and their degradation during service. In this paper, acoustic and magnetic methods have been applied to characterise the deformation - induced micro structures and the tensile property in mechanically and thermo -mechanically treated AISI type 304 stainless steel. Characterisation of the tensile deformation and changes in the microstructure have been made by ultrasonic technique. Acoustic emission technique has been used to study the characteristics of alpha' - martensite transformation during mechanical and thermo-mechanical treatments. Magnetic methods have been employed to detect the alpha'-martensite phase formed after mechanical and thermo mechanical treatments. Based on these studies, an attempt has been made: to correlate various NDT techniques with the changes in structure and tensile property.