INVESTIGATION INTO THE EFFUSION BEHAVIOR OF HYDROGEN IN QUENCHED AND TEMPERED STEELS

The effusion behaviour of hydrogen in quenched and tempered steel was investigated by means of the ultrasonic damping technique (USDT). The material 34CrMo4 was used in three tempering conditions (1: 850 N/mm2, II: 1000 N/mm2 and III: 1200 N/mm2). The influence of effusion behavi our of different media (imidazole, imidazolidine and EDTA) in dependen ce of the exposure time was determined. Additionally volumetric permea tion experiments and the determination of the hydrogen embrittlement-i ndex (VH) were performed. The results revealed, that the USDT basicall y is suitable for the quantitative, non destructive measurement of hyd rogen in quenched and tempered steel. The investigations showed a sign ificant influence of different parameters on the reproducibility of th e results. Especially the influence of media, the microstructure and t he coupling of the testing button on the material surface are importan t for the reliability of the results by using the USDT under practical conditions.