X-ray diffraction characterization of ion-implanted austenitic stainless steel

Abstract

The effect of ion implantation surface treatment in an austenitic stainless steel, AISI 304, with nitrogen and argon ions is presented in this work. The study concerns phase analysis, crystallographic texture, and in depth residual stress profile characterization by X-ray diffraction. In order to determine the residual stress depth profiles, a combination of the conventional X-ray diffraction technique, with several wavelengths radiation, and the pseudograzing incidence X-ray diffraction are used. Experimental data leads to the conclusion that the ion implantation did not create any new phase and did not influence the crystallographic texture observed before the implantation. However, concerning the residual stresses study, the results show that the initial compression residual stress profile observed in the nonimplanted surface samples changes to a tensile residual stress profile after implantation. A very important residual stress gradient is induced in the implanted surfaces and becomes more significant with the increase of ion beam fluence. In this surface layer, the tensile residual stress average value increases with the total fluence of ion beam. Ar ions seem to increase the residual stress profile more than N ions. The diffraction peak width evolution with depth is similar in nonimplanted and in implanted zones for both types of implanted ions. The peak width is much larger in the first micron of the surface layer, decreasing at a greater depth, reaching the corresponding peak value of the recrystallized material (6000-7000 nm).