Heat-to-Heat Variations in Creep-Rupture Properties of Annealed 2 1/4 Cr-1 Mo Steel

Abstract

The creep and creep-rupture properties of 13 heats of annealed 2 1/4 Cr-1 Mo steel were determined at 510 and 566°C (950 and 1050°F). The microstructures of all heats were primarily polygonal ferrite (75–80 percent); the balance was mostly bainite with 1–2 percent pearlite and scattered carbides. At each temperature the results indicated considerable data scatter for the high-stress (short rupture life) tests. As the stress was lowered, the creep and stress-rupture properties converged, which resulted in a decrease in the data scatter. Much of the variation and change in the properties could be attributed to the carbide precipitation reactions that occur in the steel.