Study of machined surface roughness parameters and their role in the degradation behaviour of a magnesium-manganese alloy

• B.P. Achar^1,2, U.K. Bhat², N. Bharadishettar², V. Marakini¹, S.P. Pai¹ and B. Sahoo²

¹ Department of Mechanical Engineering, Nitte (Deemed to be University), NMAM Institute of Technology (NMAMIT), Nitte, Udupi, Karnataka, 574110, India
² Department of Metallurgical and Materials Engineering, National Institute of Technology Karnataka, Surathkal, Mangalore, Karnataka, 575025, India

Abstract: The corrosion control of magnesium (Mg) and its alloys has been an issue of concern for its applications in biomedical and electronic components. Manganese (Mn) is an important alloying element that improves corrosion resistance by forming new phases and grain refinement in Mg alloys. Despite several corrosion mitigation techniques, the quest for novel sustainable ways remains an active area of research. In this study, the influence of the machined surface on the corrosion behaviour of the Mg-Mn alloy has been investigated. The results have been compared with a polished surface. Surface geometrical parameters and the wettability of the surfaces have been considered as parameters that influence corrosion. Tests were conducted in 3.5% NaCl solution and artificial human sweat (AHS) media. The investigation reveals that machining a surface with a correct set of parameters induces corrosion inhibition behaviour in the alloy samples in both 3.5% NaCl and AHS media. Potentiodynamic polarization test results have shown that the machined surfaces exhibit a 70.2% and 29.5% lower corrosion rate than the polished surfaces in 3.5% NaCl and AHS media, respectively. Improved surface roughness parameters, such as R_p, R_t, R_z and R_v values, as well as the oxide layer formed on machined surfaces, play a significant role in imparting corrosion resistance. The corrosion attack in the AHS medium is more severe than in the 3.5% NaCl medium on both polished and machined surfaces.

Keywords: Mg-Mn alloy, corrosion, 3.5% NaCl, artificial human sweat, face milling, surface roughness, potentiodynamic polarization

Int. J. Corros. Scale Inhib., 2026, 15, no. 1, 535-558
doi: 10.17675/2305-6894-2026-15-1-28

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