Magnetic nondestructive technology for detection of tempered martensite embrittlement

A nondestructive eddy current technique is used to evaluate tempered martensite embrittlement in 4340 AISI steels after quench and tempering in the range 240–550 °C. A relation between the responses of the magnetic induction (normalized impedance of the coil) and destructive Charpy impact test results has been established. The study shows that the eddy current method could be used to separate brittle parts due to the microstructure changes.

► Occurrence of tempered martensite embrittlement in 4340 AISI steels was evaluated.
► A reliable relation between EC output and Charpy impact test results was obtained.
► EC technique was used to separate brittle parts due to the microstructure changes.