Effect of grain orientation on the nitriding rate of a nickel base alloy studied by electron backscatter diffraction

An investigation on the microstructure, tribological and corrosion performance of AISI 321 stainless steel carbonitrided by RF plasma process

“…Nitrogen-expanded austenite phase has higher lattice expansion compared to carbon-expanded austenite [14,39]. The detected phases of the carbonitrided sample treated at 818 K are almost the same of the treated one at 723 K. As previously studied, carbonexpanded austenite phase (γ C ) can be detected at the end of the nitrided layer achieved at treatment temperature ≥723 K [18][19][20][21][22][23][24]. Therefore, the disappearance of γ C in the present diffraction patterns is due to low penetration depth of the X-ray at low incidence angle.…”

“…As observed, the thickness of the top layer is treatment temperature dependent and has a maximum value of approximately 2-3 μm at 863 K. The other two sub-layers are mostly composed of nitride and carbide phases mixed with polycrystalline solid solution phases. Czerwiec et al reported the possible achievement of two different metastable solid solutions in AISI 316 [18] and Inconel 690 [22,23]. After that, they observed such distinct nitride and carbide sub-layers with a well defined interface in AISI 316L [21].…”

“…It has been observed that the thickness, mechanical, tribological and corrosion properties of the modified stainless steel layers after a plasma surface treatment depend on the plasma processing parameters as well as on the properties of the untreated substrates [14][15][16][17]. The modified layers on austenitic stainless steel were found to be composed of complex sub-layers and have a large influence on their surface properties [18][19][20][21][22][23][24]. Some authors [25][26][27][28] have found a top layer with amorphous/nanocrystalline structure when nitriding austenitic steel and others have denied it [8].…”

Gaseous processes for low temperature surface hardening of stainless steel

“…For polycrystalline materials the phenomenon of stress-enhanced diffusion of nitrogen is reflected by a variation of the thickness of the expanded austenite zone along with crystal orientation of the austenite crystals [34].…”

Lattice rotation induced by plasma nitriding in a 316L polycrystalline stainless steel

“…The probed depth is $0.1 lm and the uncertainty on the orientation is $0.7°before nitriding. Due to the high degree of plasticity and damage induced by the nitriding process, the Kikuchi patterns after nitriding have a lower quality [28][29][30]. However, their indexation remains possible without any ambiguity for nitriding times up to 1 h. For higher nitriding times the diffraction phenomenon was enhanced by the use of a higher probe current (up to 1 nA).…”