Alloy 115 (T115) is a highly creep resistant ferritic steel containing a chromium content of 11 wt%. A
chromium content of this amount not only gives excellent high temperature creep properties (up to 650°C
[1202°F]), but also provides sulfidation resistance. The ferritic microstructure provides increased thermal
conductivity and lower thermal expansion characteristics, compared to higher-alloy austenitic materials,
which offers advantages in high temperature applications. While increased chromium content provides
better creep and high temperature oxidation resistance, the manufacturing and welding procedures are
comparable to those of Grade 91 (9 wt% Cr). Alloy 115 was developed by Tenaris, primarily for supercritical
and ultra-supercritical boiler applications, but is being considered for use in petrochemical industry
(including oil refinery) fired heaters, given its creep and sulfidation resistance. Tenaris provided the
Materials Properties Council (MPC) of Welding Research Council, Inc. (WRC) with available creep and
rupture data for analysis. E2G | The Equity Engineering Group, Inc. analyzed the results on behalf of WRC
and developed high temperature material properties based on the methodology outlined in WRC Bulletin
546. This WRC Bulletin records the data provided by the supplier, as well as the analysis performed and
resulting material properties. Material properties provided include Larson-Miller method Properties and
MPC Omega method properties for base materials. For applications outside of fired heaters, where
longitudinally welded product forms may be utilized, guidance is provided in this Bulletin for adjustments to
base material properties. This is achieved by either substitution of a weld Larson-Miller constant, ,
for the Larson-Miller constant , or by adjustments to the MPC Omega method strain rate and
creep ductility adjustment factors (respectively, ΔΩSR and ΔΩCD). In most cases, data and properties are
expressed in both US customary and metric units. It is anticipated that additional test results will be reported
in the future, potentially justifying expansion of the useful temperature range or increases to the material
creep strength.