Developments in disc materials

Appraising Forgeability and Surface Cracking in New Generation Cast and Wrought Superalloys

“…The heat treatment of samples was performed in argon-backfilled quartz ampoules for 20 minutes or 4 hours at 1030 °C, 1060 °C, or 1100 °C. These temperatures were chosen based on previous studies on the subsolvus forgeability of Udimet 720; [12,38] NB the solvus temperature commonly reported in the literature for Udimet 720 is 1143 °C to 1157 °C. [12,19,39] The heat treatment time of 4 hours was selected to represent typical industrial furnace times prior to forging.…”

“…Recently, there has been a growing interest in the widespread use of high c¢ content cast-and-wrought alloys, such as Rene´65, Udimet 720, and Udimet 720Li. [10][11][12][13][14] Alloy Inconel 718 (IN718) is still extensively employed in turbine and compressor discs, but its operation temperature is limited to 600 °C to 650 °C due to the coarsening of the c¢ and c¢¢ phases and the formation of the deleterious d phase. [10,11,[14][15][16][17] High c¢ content cast-and-wrought alloys aim to bridge the gap in temperature design space between Alloy 718 and P/M grades.…”

“…[10] An ideal high c¢ content cast-and-wrought alloy combines hot die forgeability with the highest c¢ volume fraction possible. Udimet 720 is a high strength alloy reinforced by c¢ precipitation and solid solution of Mo, W, Cr, and Co. [12] It is a versatile grade that shows a range of properties depending on thermo-mechanical processing, microstructural control, and grain size. [12,[18][19][20] In fine-grained form it possesses competitive strength levels and a temperature capability of 650 °C to 700 °C.…”

“…Udimet 720 is a high strength alloy reinforced by c¢ precipitation and solid solution of Mo, W, Cr, and Co. [12] It is a versatile grade that shows a range of properties depending on thermo-mechanical processing, microstructural control, and grain size. [12,[18][19][20] In fine-grained form it possesses competitive strength levels and a temperature capability of 650 °C to 700 °C. [10,18,21] Efforts have also been devoted to developing new 718-type alloys, which would benefit from sluggish precipitation kinetics and a non-strengthening high-temperature phase (d) for ease of hot working and grain refinement.…”

“…Udimet 720 is difficult to forge, but previous studies indicate that it can be successfully forged via ring rolling, hot die forging, and superplastic isothermal forging. [10,19,25] Some authors have investigated the isothermal deformation of Udimet 720 [12,19,26] and its variant Udimet 720Li. [27][28][29][30] but studies on its hot die forgeability, by means of mimicking die chilling, are sparse.…”