The Influence of Nominal Composition on the Microstructure, Tensile Properties, and Weldability of Cast Monel Alloys

• Published in: Metallurgical and materials transactions. A, Physical metallurgy and materials science Vol. 55; no. 2; pp. 580 - 597
• Main Authors: Farnin, Christopher J., Coker, Eric N., Salinas, Perla A., DuPont, John N.
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.02.2024; Springer Nature B.V
• Subjects: Characterization and Evaluation of Materials; Chemistry and Materials Science; Composition; Copper; Corrosion resistance; Crack initiation; Ductility; Electron probe microanalysis; Eutectic reactions; Fracture mechanics; Heat treating; Industrial applications; Intermetallic compounds; Manganese; Materials Science; Mechanical properties; Metallic Materials; Microstructure; Monel (trademark); Nanotechnology; Nickel base alloys; Nucleation; Original Research Article; Silicides; Silicon; Solidification; Structural Materials; Surfaces and Interfaces; Tensile properties; Tensile tests; Thermal analysis; Thermodynamic properties; Thin Films; Weldability
• ISSN: 1073-5623; 1543-1940
• DOI: 10.1007/s11661-023-07269-5

Cast Monel alloys are used in many industrial applications that require a combination of good mechanical properties and excellent resistance to corrosion. Despite relative widespread use, there has been limited prior research investigating the fundamental composition–structure–property relationships. In this work, microstructural characterization, thermal analysis, electron probe microanalysis, tensile testing, and Varestraint testing were used to assess the effects of variations in nominal composition on the solidification path, microstructure, mechanical properties, and solidification cracking susceptibility of cast Monel alloys. It was found that Si segregation caused the formation of silicides at the end of solidification in grades containing at least 3 wt pct Si. While increases to Si content led to significant improvements in strengthening due to the precipitation of β 1 -Ni 3 Si, the silicide eutectics acted as crack nucleation sites during tensile loading which severely reduced ductility. The solidification cracking susceptibility of low-Si Monel alloys was found to be relatively low. However, increases to Si concentration and the onset of associated eutectic reactions increased the solidification temperature range and drastically reduced cracking resistance. Increases in the Cu and Mn concentrations were found to reduce the solubility limit of Si in austenite which promoted additional eutectic formation and exacerbated the reductions in ductility and/or weldability.