SUPERALLOY 706 LARGE FORGINGS BY ESR

Alloy 706 is suitable for large forgings, but its precipitation behavior and mechanical properties are greatly affected by small differences in manufacturing factors. In this study, effects of each manufacturing factor on tensile properties of Alloy 706 were systematically investigated. As a result, it was clarified that tensile properties were determined by five factors: titanium content, niobium content, temperature and time of the 1 st step in double aging treatment, and cooling rate from solution treatment. From the regressive analysis of this laboratory data, a prediction equation for tensile strength with the five factors was presented. Then, six large size trial disks were manufactured from VIM - ESR double-melted ingots with the five process parameters that were selected by using the prediction equation to give desired tensile properties. Tensile tests were performed with specimens taken from rim and core of the trial disks. The tensile strength of trial disks was in good agreement with that from obtained the prediction equation. The whole tensile properties were all acceptable for the specified value and were comparable to those from VIM ESR - VAR triple-melted ingot in literature.