Influence of austenitizing and tempering on the corrosion behavior and sensitization of martensitic stainless steel X50CrMoV15

Heat treatments are commonly applied in the martensitic stainless steels to achieve high wear resistance and hardness; however, they can lead to a decrease in corrosion resistance due to the precipitation of chromium-rich carbides. The present work investigates the effect of austenitizing and tempering parameters on the microstructure, hardness, and passivation and reactivation currents of AISI 440C. A double-loop electrochemical potentiodynamic reactivation test is performed to evaluate the dissolution and precipitation of chromium-rich carbides. The volume fraction of phases after heat treatment is estimated by X-ray diffraction. Results show that an increase in the austenitizing temperature leads to an increase in the carbide dissolution, and also in the amount of retained austenite. As a consequence, low passivation and reactivation currents are obtained. When austenite is the main phase, the increase of austenitizing time contributed to an increase in the degree of sensitization due to austenite grain boundary carbon enrichment. However, the presence of austenite after tempering kept part of the carbon in a solid solution resulting in low passivation and reactivation currents.

Section: Corrosion Testmentioning

confidence: 93%

Section: Corrosion Testmentioning

confidence: 99%

Section: Corrosion Testmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Effect of heat treatment on the chromium‐depleted zones of a high carbon martensitic stainless steel

Siqueira

Alves

Luiz

et al. 2021

“…Such inclusions are usually present in martensitic stainless steels and cause pitting. [21][22][23][24]…”

Section: Surface Morphologymentioning

confidence: 99%

Effects of nitric acid passivation on the corrosion behavior of ZG06Cr13Ni4Mo stainless steel in simulated marine atmosphere

Zhang

Wei

Yang

et al. 2020

ZG06Cr13Ni4Mo martensitic stainless steel was nitric acid‐passivated to improve its corrosion performance. The effects of nitric acid passivation on the surface morphology, chemical composition, electrochemical properties, semiconductor behavior, and long‐term corrosion performance of the stainless steel were investigated using various analytical techniques. An in‐depth analysis of X‐ray photoelectron spectroscopy (XPS) showed that the passive film formed after the acid passivation process showed high thickness and a duplex character as it consisted of a hydroxide layer and an oxide layer. The oxide layer affected the corrosion resistance and thickness of the passive film. The thickness of the passive film was calculated theoretically as well as experimentally by fitting the electrochemical impedance spectroscopy and XPS results. The electrochemical tests revealed that the dramatic increase in the corrosion resistance of the stainless steel after the passivation was due to the formation of a thick, low‐disorder passive film rather than Cr enrichment. The removal of inclusions resulted in higher pitting resistance, whereas the increased roughness showed a negative effect on the corrosion behavior of the stainless steel. During the wet–dry cyclic tests, the modification of the passive film was examined. The passivated stainless steel exhibited good corrosion resistance for up to 50 days of exposure in the simulated environment.

DL‐EPR and AFM study of sensitization of a 17%Cr multiphase stainless steel

Tavares

Sampaio

Pérez

et al. 2022

The corrosion behavior of a 17Cr multiphase martensitic stainless steel quenched (1000°C, water cooling) and tempered at different temperatures was determined using the double-loop electrochemical potentiokinetic reactivation (DL-EPR) test. The specimen tempered at 550°C showed the highest degree of sensitization. For the specimen treated at 600°C, a healing process was observed, followed by a second sensitization at 625°C coincident with an increase in the austenite volume fraction. This phase was quantified using the magnetic method and an increase in this phase was observed with the tempering temperature. The DL-EPR results were correlated with surface aspects obtained by atomic force microscopy.