Study on nondestructive characterized mixed microstructure of 30Mn2SiV bar using ultrasonic relative phase velocity

An experimental immersion beam focus technique has been developed to measure relative phase velocity of ultrasonic waves through three kinds of non-quenched and tempered 30Mn2SiV Steel for Sucker rod with different mixed microstructure.The microstructures of three kinds of specimens are mixed with lamellar pearlite,ferrite,globular pearlite,upper bainite with different compound and percentage.The relationship between ultrasonic relative phase velocity and mixed microstructure was investigated.