Differences among Methods A/B/C, the gap between test conditions and actual service conditions, and the limits on how results can be used.
ASTM G48 uses FeCl3 solution to evaluate the pitting resistance of stainless steels, commonly with Method A (6% FeCl3, 24 h, at various temperatures).
Points to note when interpreting results:
- What is reported is the critical pitting temperature (CPT) or the corrosion rate/mass loss.
- The test conditions are strongly oxidizing with high chloride concentration, harsher than most actual service conditions, so service life cannot be directly extrapolated.
- Surface condition (weld seams, oxide scale, roughness) strongly affects results, so specimens must match the actual condition.
- 304/316L show clear differences under Method A, and 2205 is usually significantly better than 316L.
Conclusions should be stated as relative ranking and suitability judgments, not as "how many years it will last."
