PSI - Issue 82

L.F. Guedes et al. / Procedia Structural Integrity 82 (2026) 199–205 Guedes et al. / Structural Integrity Procedia 00 (2026) 000–000

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Fig. 8. Tensile specimens after test: (a) N350; (b) N400; (c) N570.

(a) (b) Fig. 9. Microstructure near the fracture surfaces of specimens: (a) N350; (b) N400.

(a) (c) Fig. 10. Tensile Specimen N570: (a-b)Secondary cracks; (c)Fracture surface (NL= nitrided layer). (b)

4. Conclusions The specimens of supermartensitic stainless UNS S41426 for tensile testing which submitted to plasma ion nitriding presented nitrided layers containing microcracks. During tensile tests, the failure of the nitrided layer influenced the overall result, provoking a moderate embrittlement effect in specimens nitrided at 350 o C and 400ºC. Despite several microcracks nucleating in the nitrided layer, the specimens still presented in overall ductile fracture. In samples nitrided at 570 o C the nitrided layer was thicker, with two sub-layers. The layer was very brittle, with secondary cracks nucleating in stress concentrators created by the turning machining. As a consequence, the tensile test of the material nitrided at 570 o C i typical of a brittle material. Acknowledgements The authors acknowledge Conselho Nacional de Desenvolvimento Científico e Tecnológico - Brasil (CNPq 308244/2022-2; 308930/2025-8), Fundação de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ E-