Effect of Grain Size on Steam Oxidation for Shot-Peened Stainless Steels

摘要

The growth behavior of oxide scale in a laboratory steam environment has been conducted for the shot-peened 18Cr-8Ni stainless steels differing in grain size. Both steels (fine grained and coarse grained) have demonstrated almost the same steam oxidation behavior reacted at 700°C for up to 2000h, which had excellent oxidation resistance due to formation of a protective Cr_O_3 scale. After the exposure of 4000h, however, nodule-like oxide occurred on the coarse grained steel, while the fine grained steel still remained the uniform Cr_O_3 scale. These behaviors well explained in terms of changes of the outward Cr flux due to recovery and recrystallization of the deformed structure. This result has proven that the shot-peened tube composed of fine grain structure is capable of combat against the steam oxidation at high temperatures.