Optimization of the Passivation Process for AM 350 and CUSTOM 450 Stainless Steels Using Taguchi Methodology and Gray...

Area of Science:

• Materials Science
• Corrosion Engineering
• Surface Engineering

Background:

• Precipitation-hardening stainless steels (PHSS) like AM350 and CUSTOM 450 are crucial in aerospace.
• Their corrosion resistance is critical but challenging to optimize due to complex passivation processes.
• Nitric acid passivation, while common, has environmental and safety concerns.

Purpose of the Study:

• To optimize passivation parameters for PHSS alloys (AM350, CUSTOM 450) to enhance corrosion resistance.
• To implement a robust multi-response optimization methodology for complex passivation processes.
• To explore alternatives to nitric acid passivation.

Main Methods:

• Design of Experiments using the Taguchi method to study factors like material, passivation solution, concentration, temperature, and time.
• Gray Relational Analysis (GRA) for multi-response optimization.
• Analysis of Variance (ANOVA) to determine the significance of each parameter.
• Corrosion resistance evaluation using H2SO4 and NaCl solutions.

Main Results:

• Optimized parameters identified: PHSS AM350, citric acid/oxalic acid solution (25% v/v), 50°C, 120 min.
• Achieved up to 55% improvement in corrosion resistance.
• Taguchi/GRA integration proved effective for complex, multi-response optimization.

Conclusions:

• The integrated Taguchi, GRA, and ANOVA approach provides an efficient method for optimizing PHSS passivation.
• The developed parameters significantly reduce corrosion rates, offering a viable alternative to nitric acid passivation.
• This research enhances the durability and performance of critical aerospace materials.