The high-temperature tension tests for Monel 400 specimens were conducted at 600°C, 700°C, 800°C, 900°C, 1000°C, and 1100°C. The elongation, reduction of area, and fracture surface at elevated temperatures are illustrated respectively.

Elongation & Reduction of Area Chart for Monel 400

When the test temperature increases from 600°C to 700°C, the elongation value decreases from 13.26% to 11.22% while the reduction of area decreases from 24.26% to 20.47%. The ductility of Monel 400 decreases as the temperature goes up in this range. As the test temperature increases from 700°C to 900°C, the elongation value increases from 11.22% to 20.05% while the reduction of area increases from 20.47% to 60.05%. The ductility of Monel 400 increases as the temperature goes up in this range. As the temperature rises up from 900°C to 1100°C, the ductility decreases again. Monel Alloy 400 exhibits hot brittleness between 600°C and 800°C.

The Fracture of Monel 400 Specimens at Elevated Temperatures

From the macrostructure after fracture, obvious necking of Monel 400 is observed at temperatures between 800°C to 1000°C and it achieves maximum at 900°C. It proves that Monel 400 has improved ductility at this temperature range.

The microstructure of the fracture surface of Monel 400 at 600°C, 700°C and 800°C are attained by SEM method. Both pictures A and B exhibit quasi-cleavage fracture in river pattern. It indicates the brittle fracture. Some dimples are observed in Picture C except for cleavage fracture. It proves that the ductility shall be improved at 800°C.