Aging behavior of 17-4 PH stainless steel studied using XRDLPA for separating the influence of precipitation and dislocations on microstrain

The aging behavior of precipitation hardenable 17-4 PH stainless steel is studied by analyzing the changes in microstrain, crystallite size, and dislocation density derived from the modified Williamson-Hall (mWH) method and the Fourier analysis of XRD profiles. Aging treatment of this steel at 380, 430, and 480 degrees C for 0.5, 1, and 3 h durations leads to changes in the microstrain due to precipitation and substructural changes caused by dislocation annihilation. The microstrain estimated from the mWH method is dominated by the precipitate-induced effects. The influence of precipitates and dislocations on the mean squared strain <epsilon(2)(L)> are separated by fitting the variation of <epsilon(2)(L)> with an expression P-0 + P-1/L + P-2/L-2, where the parameter (P-0)(0.5) and P-1 are shown to be related to the precipitate-induced and dislocation density-induced microstrain, respectively. The study shows that the XRD profile analysis can be used to separate the combined effects of precipitation and dislocation annihilation.