Quenching and tempering effect on the corrosion resistance of nitrogen martensitic layer produced by SHTPN on AISI 409 steel

SURFACE & COATINGS TECHNOLOGY

卷:395

Article

Berton, Elisiane Maria¹  Klein das Neves, Julio Cesar¹  Mafra, Marcio¹  Borges, Paulo Cesar¹ 

[1] Univ Tecnol Fed Parana, Mech Engn Dept, UTFPR, Grp Res Mat Tribol & Surfaces GrMaTS, BR-80230901 Curitiba, Parana, Brazil

关键词: SHTPN;    AISI 409;    Nitrogen enrichment;    High nitrogen stainless steel;    Nitrogen martensite;    Corrosion resistance;   

DOI  :  10.1016/j.surfcoat.2020.125921

来源: Elsevier

【 摘 要 】

This work presents the application of Solution Heat Treatment after Plasma Nitriding (SHTPN) followed by requenching and tempering to the AISI 409 stainless steel aiming to increase hardness with no compromise of corrosion resistance. The SHTPN process consists of applying solution treatment to a previously plasma nitrided surface, promoting the dissolution of nitrides and the formation of a nitrogen-rich layer, in which nitrogen is in solid solution. When applied to ferritic stainless steels, SHTPN allows the obtention of a high-nitrogen martensitic layer. It is presented an evaluation of the effects of requenching (from 950 and 1050 degrees C) and tempering (at 250, 450 and 650 degrees C) processes on the microstructure, hardness, and corrosion resistance of the nitrided layer of samples previously treated by SHTPN. Corrosion resistance was assessed through cyclic potentiodynamic polarization tests carried out in NaCl 0.5 mol/L, according to ASTM G150. Optical and scanning electron microscopy, wavelength dispersive spectroscopy, and X-ray diffraction were applied to microstructural and phase characterization. Surface hardening was evaluated by Vickers microhardness tests. Results have shown that the requenching of SHTPN samples promoted a deepening of the nitrided layer and microstructure refinement. The process with requenching from 1050 degrees C and tempering at 250 degrees C led to increasing both hardness and corrosion resistance. These results confirmed that nitrogen in solid solution increases the hardness and the potential for pit nucleation in the AISI 409 stainless steel.

【 授权许可】

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