Oxidation Behavior of Maraging 300 Alloy Exposed to Nitrogen/Water Vapor Atmosphere at 500 °C

Mauro Andres Cerra Florez,Marcelo José Gomes Da Silva,Jorge Luiz Cardoso,Moises Bastos-Neto,Joan Josep Roa Rovira,Hamilton Ferreira Gomes De Abreu,Antonio Manuel Mateo García,Gemma Fargas Ribas

doi:10.3390/met11071021

Mauro Andres Cerra Florez, Marcelo José Gomes Da Silva + Show 6 more

Open Access

https://doi.org/10.3390/met11071021

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Abstract

Aging heat treatments in maraging steels are fundamental to achieve the excellent mechanical properties required in several industries, i.e., nuclear, automotive, etc. In this research, samples of maraging 300 alloy were aged using a novel procedure that combines different steps with two atmospheres (nitrogen and water vapor) for several hours. The oxidized surface layer was chemical, microstructural and micromechanically characterized. Due to the thermodynamic and kinetic conditions, these gases reacted and change the surface chemistry of this steel producing a thin iron-based oxide layer of a homogeneous thickness of around 500 nm. Within the aforementioned information, porosity and other microstructural defects showed a non-homogeneous oxide, mainly constituted by magnetite, nickel ferrite, cobalt ferrite, and a small amount of hematite in the more external parts of the oxide layer. In this sense, from a chemical point of view, the heat treatment under specific atmosphere allows to induce a thin magnetic layer in a mixture of iron, nickel, and cobalt spinel ferrites. On the other hand, the oxide layer presents an adhesive force 99 mN value that shows the capability for being used for tribological applications under sliding contact tests.

Highlights

Maraging steels are known for their ultra-high-strength (UHS), which is attributed to the combination of a martensitic matrix with precipitates induced by an aging heat treatment, leading the material to be known as maraging steel [1]
The spectrum is in agreement with those reported in [20]
This of the oxidation maraging 300amounts alloy in of water vaporknown and nitroat 500 showed that, althoughbehavior there areofconsiderable elements for gen 500 °C showed that,the are considerablephenomena amounts ofdid elements known theiratcorrosion resistance, kinetic there and thermodynamic not allow the for their corrosion kinetic phenomena didimposed not allow formation of oxidesresistance, that could the protect the and steelthermodynamic from the chemical degradation by the formation of oxides that could protect the steel from the chemical degradation imthe exposure conditions

Summary

Introduction

Maraging steels are known for their ultra-high-strength (UHS), which is attributed to the combination of a martensitic matrix with precipitates induced by an aging heat treatment, leading the material to be known as maraging steel [1]. Their fantastic properties are mainly attributed to their alloying elements. In this sense, these steels presents a solid solution of nickel (Ni), cobalt (Co), molybdenum (Mo), titanium (Ti), low carbon content (C), and aluminum (Al) [1,2]. Al raises the tensile strength by hardening the martensitic phase [3,5,6]

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