In Situ Thermogravimetric Analysis of Curved Surfaces During High-Temperature Oxidation

Area of Science:

• Materials Science
• Metallurgy
• Surface Engineering

Background:

• Hot-finished, welded conveyance tube manufacturing is energy-intensive, leading to rapid surface oxidation on curved sections.
• Existing computational and theoretical studies on curved surface oxidation face validation challenges due to experimental limitations in replicating industrial conditions.
• Accurate assessment of oxidation in industrial settings is crucial for optimizing manufacturing processes and material performance.

Purpose of the Study:

• To investigate the challenges of in situ thermogravimetric analysis (TGA) for assessing surface oxidation in cylindrical conveyance tubes.
• To compare experimental TGA results with computational predictions and industrial normalization data for an as-welded conveyance tube.
• To identify limitations in current methods for validating computational models of oxidation during tube manufacturing.

Main Methods:

• Utilized thermogravimetric analysis (TGA) on an as-welded conveyance tube under controlled conditions.
• Employed a refractory dummy sample to quantify thermal buoyancy and flow-induced vibration effects during TGA.
• Compared TGA oxide mass gain and thickness (via electron microscopy) with computational model predictions and industrial data.

Main Results:

• A strong agreement (5% discrepancy) was observed between the oxide mass gain predicted by the computational model and the TGA experimental results.
• Significant discrepancies were found in oxide thickness gain measurements between industrial and experimental results, as assessed by electron microscopy.
• The study identified key factors influencing these discrepancies, including transient heating, oxide porosity, atmospheric variations, and thermomechanical operations.

Conclusions:

• Thermogravimetric analysis (TGA) shows promise for validating computational models regarding oxide mass gain in conveyance tube manufacturing.
• Further research is needed to refine computational models to accurately predict oxide thickness, accounting for transient effects and process variations.
• Improved experimental and computational approaches are essential for accurate simulation and optimization of surface oxidation during industrial conveyance tube production.