Abstract
The effect of thermal aging at 793 and 873 K of quenched-and-tempered thick-section 9wt.%Cr1wt.%Mo steel on its oxidation behaviour has been studied in air at 773 K for a maximum exposure of 2000 h. The oxidation rate was found to increase with increasing aging temperature. This increase has been attributed to the depletion of free chromium in the alloy matrix during aging with a corresponding enrichment of the chromium content of M23C6 at the boundaries of the lath martensite and proeutectoid ferrite present inherently in the microstructure. The enhancement of the oxidation rate of the quenched-and-tempered material upon thermal aging has been confirmed by acoustic emission (AE) tests. These showed more AE activity for an aged specimen during oxidation as well as during subsequent cooling, indicating thicker scale formation leading to more cracking and/or spalling. The influence of chromium depletion, due to thermal aging, on the oxide scale composition has also been confirmed by scanning electron microscopy and energy-dispersive X-ray analysis of the oxide-alloy interfaces.
| Original language | English |
|---|---|
| Pages (from-to) | 299-306 |
| Number of pages | 8 |
| Journal | Materials Science and Engineering A: Structural Materials: Properties, Microstructure and Processing |
| Volume | 148 |
| Issue number | 2 |
| DOIs | |
| Publication status | Published - 14 Dec 1991 |
| Externally published | Yes |
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