Study on Creep Crack Growth Properties for 2 1/4Cr-1Mo Steel

Abstract

The effect of heat treatment on the creep crack growth properties of 21/4Cr-1Mo steel was determined and then compared with the creep crack behaviour of actual weld joints. The results obtained are summarized as follows:
(1) Creep crack growth properties are remarkably changed by heat treatment.
(2) The creep crack growth rate increased with decreasing ductility, in the following order. Simulated HAZ>Water Quenched>Normalized-tempered>Annealed.
(3) The J-da/dt curve on a high ductility condition is different from that on a low ductility condition even for the same steel.
(4) Creep cracks advanced in the coarse grain heat affected zone in actual weld joints of 1Cr-1/2Mo steel. Creep crack resistance is improved by reduction of hardness due to stress relieving.