Title

PLASMA NITRIDING OF A PRECIPITATION HARDENING STAINLESS STEEL TO IMPROVE EROSION AND CORROSION RESISTANCE

PLASMA NITRIDING OF A PRECIPITATION HARDENING STAINLESS STEEL TO IMPROVE EROSION AND CORROSION RESISTANCE

Authorship

Cabo, Amado; Brühl, Sonia P.; Vaca, Laura S.; Charadia, Raúl; Dalibón, Eugenia L.

DOI

10.5151/2594-5327-16961

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Abstract

Precipitation hardening stainless steels are used as structural materials in the aircraft and the chemical industry because of their good combination of mechanical and corrosion properties. The aim of this work is to analyze the structural changes produced by plasma nitriding in the near surface of Thyroplast PH X Supra®, a PH stainless steel from ThyssenKrupp, and to study the effect of nitriding parameters in wear and corrosion resistance. Samples were first aged and then nitriding was carried out in an industrial facility at two temperatures, with two different nitrogen partial pressures in the gas mixture. After nitriding, samples were cut, polished, mounted in resin and etched with Vilella reagent to reveal the nitrided case. Nitrided structure was also analyzed with XRD. Erosion/Corrosion was tested against sea water and sand flux, and corrosion in a salt spray fog (ASTM B117). All nitrided samples presented high hardness. Samples nitrided at 390oC with different nitrogen partial pressure showed similar erosion resistance against water and sand flux. The erosion resistance of the nitrided samples at 500oC was the highest and XRD revealed nitrides. Corrosion resistance, on the contrary, was diminished; the samples suffered of general corrosion during the salt spray fog test.

 

Precipitation hardening stainless steels are used as structural materials in the aircraft and the chemical industry because of their good combination of mechanical and corrosion properties. The aim of this work is to analyze the structural changes produced by plasma nitriding in the near surface of Thyroplast PH X Supra®, a PH stainless steel from ThyssenKrupp, and to study the effect of nitriding parameters in wear and corrosion resistance. Samples were first aged and then nitriding was carried out in an industrial facility at two temperatures, with two different nitrogen partial pressures in the gas mixture. After nitriding, samples were cut, polished, mounted in resin and etched with Vilella reagent to reveal the nitrided case. Nitrided structure was also analyzed with XRD. Erosion/Corrosion was tested against sea water and sand flux, and corrosion in a salt spray fog (ASTM B117). All nitrided samples presented high hardness. Samples nitrided at 390oC with different nitrogen partial pressure showed similar erosion resistance against water and sand flux. The erosion resistance of the nitrided samples at 500oC was the highest and XRD revealed nitrides. Corrosion resistance, on the contrary, was diminished; the samples suffered of general corrosion during the salt spray fog test.

Keywords

PH stainless steel; Plasma nitriding; Corrosion.

PH stainless steel; Plasma nitriding; Corrosion.