Haynes HR-120 alloy (UNS N08120) is a nickel–iron–chromium alloy that exhibits high strength at elevated temperature and resistance to carburising and sulphidising environments. These properties make this alloy suitable for the production of components of land based turbines, including rings. Manufacture and heat treating of such rings require strict control of the processing variables, such as temperature and deformation ratios, as well as the time and temperature of the solution treatment, due to their effect on microstructure and mechanical properties. It is common practice to treat this alloy at temperatures above 1100°C to promote dissolution of undesired particles and recrystallisation of deformed structures, but it has been found that grain coarsening can occur during treatment. The present work presents the results of a series of solution heat treatments that were performed within a broad range of temperatures on industrial ring rolled pieces. It was found that the increment in time and temperature enhances the dissolution of intergranular precipitates that result in the improvement of mechanical properties, but grain coarsening is observed to occur when the material is treated for long times and high temperatures. The best combination of mechanical properties and grain size was obtained by treating the material for half an hour at 1050°C.
Alloy 909 is a Ni–Fe–Co alloy that exhibits a low coefficient of thermal expansion and high strength at elevated temperatures. These characteristics are suitable for demanding high temperature uses such as turbine components for aerospace and energy generation. The mechanical properties are achieved by heat treatment (solution and aging) that affects the microstructural characteristics such as grain size and precipitation of intergranular and transgranular particles. This work summarises the results of trials conducted to determine the conditions that assure the desired mechanical properties in high temperature ring rolled pieces. Results of tensile, hardness and stress rupture tests are complemented by microstructural analyses. These studies allowed for establishing a robust method for the manufacture of rings; no degradation of the product, either metallurgical or due to properties, has been reported after the method was implemented.
Haynes™ HR-120™ alloy is a solid-solution-strengthened heat resistant alloy. The main characteristics of this alloy are strength at elevated temperature combined with resistance to carburizing and sulfidizing environments. Typical solution heat treatment for this alloy is usually performed above 1100°C. Solution heat treatment promotes non-desired precipitates to dissolve and, if deformation parameters are adequate, re-crystallization after forging procedures. It is reported that the solution temperature can also promote non-controlled grain coarsening. This investigation summarizes results on the effect of solution heat treatment on the microstructure of forgings when it is performed at 1000°C, 1050°C and above 1100°C. The experimental conditions resemble industrial environments. The obtained results include the alloy microstructural evolution by optical microscopy and Scanning Electron Microscopy (SEM) and the effect of these heat treatments on mechanical properties such as tensile, hardness and stress-rupture properties.
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