High Temperature Heat Capacity of Alloy D9 Using Drop Calorimetry Based Enthalpy Increment Measurements

Abstract

Alloy D9 is a void-swelling resistant nuclear grade austenitic stainless steel (SS) based on AISI type 316-SS in which titanium constitutes an added predetermined alloying composition. In the present study, the high-temperature enthalpy values of alloy D9 with three different titanium-to-carbon mass percent ratios, namely Ti/C = 4, 6, and 8, have been measured using inverse drop calorimetry in the temperature range from 295 to 1323 K. It is found that within the level of experimental uncertainty, the enthalpy values are independent of the Ti–C mass ratio. The temperature dependence of the isobaric specific heat CP is obtained by a linear regression of the measured enthalpy data. The measured CP data for alloy D9 may be represented by the following best-fit expression: CP (J · kg −1 · K −1 ) = 431 + 17.7 × 10 −2 T + 8.72 × 10 −5 /T 2 . It is found that the measured enthalpy and specific heat values exhibit good agreement with reported data on 316 and other related austenitic stainless steels.