Issue 36

F. Z. Liu et alii, Frattura ed Integrità Strutturale, 36 (2016) 139-150; DOI: 10.3221/IGF-ESIS.36.14 146 trapping hydrogen can be estimated qualitatively according to the peak value. The hydrogen effusion peak temperature would change if the heating rate was changed; when heating rate increases and heating time reduces, hydrogen effusion peak moves towards high temperature. The correlation between heating rate and hydrogen effusion peak temperature [21] is: E 2 E Ae a P RT a P RT   (1) In the formula, E a refers to activation energy of hydrogen trap,  refers to heating rate; T p refers to hydrogen effusion peak temperature, A is a constant R is a gas constant. After taking the logarithm of both sides of formula (1) and differentiation, we get 2 ln( / ) (1/ ) a P P E T T R      (2) It can be known from formula (2) that, 2 ln( / ) P T  and 1/ P T was in a linear correlation. Hence Ea could be calculated using linear fitting method. Hydrogen effusion peak temperature of hydrogen effusion curves of experimental samples processed at different heating rates is shown in Tab. 5. The correlation between 2 ln( / ) P T  and 1/ P T could be obtained in Fig. 8. Besides, the value of E / a R was obtained after solving slope with linear fitting, and then the value of activation energy E a was obtained. Heating rate, °C /h State of samples Hydrogen effusion peak temperature of diffusible hydrogen, °C Hydrogen effusion peak temperature of non-diffusible hydrogen, °C 100 Quenching state 152 396 100 °C tempering state 129 411 200 °C tempering state 132 411 400 °C tempering state 126 390 200 Quenching state 201 438 100 °C tempering state 179 430 200 °C tempering state 186 427 400 °C tempering state 160 408 400 Quenching state 260 465 100 °C tempering state 251 455 200 °C tempering state 244 453 400 °C tempering state 222 447 Table 5 : Hydrogen effusion peak temperature of hydrogen effusion curves of experimental materials processed by different heating rate.