Acoustic emissions generated during Lüders band elongation of tempered medium carbon steel

This paper presents studies on acoustic emissions generated during Luders band elongation of tempered medium carbon steel. Tensile testing of water quenched (1223 K for 1 h) as well as water quenched and tempered (923 K for 5 and 25 h) specimens has been carried out, along with monitoring of acoustic emission (AE) signals. The AE rms voltage and predominant frequencies generated during the Luders deformation have been analyzed. An attempt has been made to correlate the peak height (amplitude) of predominant frequencies with tempering time and to explain the observations with the help of dislocation pile-up breakaway and recrystallization of tempered martensite. The understanding of the variation of the amplitude of the frequency components has given enhanced insight into the tensile deformation of the tempered medium carbon steel during the Luders band elongation.