Monitoring fracture of high-strength steel under tensile and constant loading using acoustic emission analysis

In the aeronautical industry, many critical components are made of high-strength steels. These steels have high tensile strength but are sensitive to corrosion and to the hydrogen embrittlement phenomenon. This study examines how acoustic emission could be used to detect hydrogen embrittlement of high-strength steels and reduce the duration of the standard test. Acoustic emission (AE) was coupled with sustained load testing at 75% of the material fracture stress for 200h as prescribed in ASTM standard F519. Tensile strength tests were also conducted to determine the mechanical characteristics and acoustic signature of the mechanisms of damage that progress to material fracture. The results show that the time required for sustained load tests can be shortened, based on the emission of acoustic events by the hydrogen-embrittled test coupons from the beginning of the test and after certain lengths of time. Scanning electron microscopy imaging of the fracture surfaces showed a very good correlation with the recorded acoustic event signatures.