1. Verification of Alumina formation on AFA Stainless Steels
Goyko Rajak, Violet Ahnen
Dr. Ben Church
Jim myers & josh Pichette, MetalTek International

2. Background and Application
Alumina-forming Austenitic Stainless Steel
New alloy, comparable to traditional HP stainless steel alloy
Thermodynamically stable alumina layer
Ethylene Cracking
HP stainless steel alloy traditionally used
Decoking Maintenance
Less maintenance with AFA material

3. Goal & Objectives Goal​
Design and implement quality assurance specifications which verify the formation of aluminum oxide on the pull-bored surface of each batch of AFA stainless steel reformer tubes at MetalTek International. ​​
Objectives​
Create a specification for the oxidation procedure & SEM analysis.  ​
Perform research on alternative methods for verification.

4. Methodology Oxidation in Pure Steam SEM & EDS analysis XRD analysis
XPS analysis
Constant-current coulometry

5. Results - SEM & EDS

6. Results - XPS
Binding Energy (eV)

7. Results - XRD 2θ

8. Conclusion Method Pros Cons SEM/EDS -Identifies Al, Cr, Fe, Ni, & O
-Visually identifies alumina layer
-Preferred method by customer
-Expensive and potentially time consuming
XRD
-Inexpensive & easy to use
-Alumina peaks weak in intensity
-Penetration depth exceeds alumina layer
XPS
-Electron beam effective depth will penetrate further than the alumina layer
-Very sensitive to contaminants
-Requires calculations to draw conclusions on oxides
-Expensive
Electrochemical Reduction
-Inexpensive
-Thickness of oxide layer can be quantified
-Difficult to show layer continuity