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Tuesday, November 1, 2011 - 12:00 PM

New Heat Treatment Temperatures for HR-120 Alloy

O. Covarrubias, Frisa Aerospace SA de CV, Santa Catarina, Mexico; R. Colas, Universidad Autonoma de Nuevo Leon, San Nicolas, Mexico

Haynes HR-120 alloy is a heat-resisting alloy that is characterized by a high mechanical strength and high resistance to oxidizing, carburizing and sulfidizing environments at temperatures up to 1095°C. Like any other alloy, the microstructural characteristics and mechanical properties are consequence of the processing route during the manufacture of a given component and the heat treatment after it. In the specific case of forged rings made from this alloy, parameters like temperature and deformation ratios are critical to promote the microstructure required to achieve the desired properties.

Applications for this alloy include components used in the fabrication of land-based turbines for energy generation. Some of these components can be manufactured by ring rolling procedures, where main parameters to control are related to hot-working conditions as temperature ranges and deformation ratios. After ring-rolling processes, manufactured rings must be exposed to heat treatment conditions to promote desired properties.

Haynes HR-120 alloy can be heat treated at different temperature ranges, depending on their condition; the temperature range of 1175 to 1230°C is favored in as-cast pieces, as homogenization and solution of primary carbides take place at shorter times, however lower temperatures are preferred for wrought pieces. Rapid cooling, such as forced convection or immersion in polymer or water quench tanks, is recommended to assure a fine grain size and avoid precipitation of undesired particles.

The aim of this work is to present the results of a series of solution treatments carried out on samples cut from hot rolled rings made from HR-120®. The study was conducted to optimize the treatment that will allow for the consistent microstructure and mechanical properties that are required by customers.


Summary: HR-120 alloy is a Ni-Fe-Cr alloy that exhibits high strength at elevated temperature and resistance to carburizing and sulfidizing environments, making this alloy suitable for the manufacture of components for land-based turbines for energy generation. Some of these components can be fabricated by ring-rolling procedures, where parameters as deformation ratio and temperature processing are important factors to control. Annealing procedures are needed for promotion of desired microstructural and mechanical characteristics by solid-solution-strengthening mechanisms. This contribution summarizes results when HR-120 alloy is exposed to several annealing conditions: mechanical testing and microstructural evaluations are performed to validate proposed heat treating temperatures in order to promote best mechanical properties and grain size control.