The Importance of Passivation for Stainless Steel: Corrosion Resistance & Compliance with Australian Standards

Stainless steel is widely used in various industries due to its excellent corrosion resistance and durability. However, it is essential to understand that even stainless steel is not entirely immune to corrosion. To maintain its long-lasting properties and to comply with Australian standards, passivation is a crucial process that must be employed.

The Need for Passivation

Stainless steel contains a protective layer of chromium oxide on its surface that shields it from most corrosive environments. This passive film is self-repairing when damaged. However, during manufacturing processes like welding, machining, or forming, the passive layer may be compromised, leading to the creation of active sites susceptible to corrosion. These active sites can accelerate corrosion, especially in aggressive environments such as coastal areas with high salt content or chemical-rich industrial settings.

The Process

Passivation is a surface treatment that removes free iron, contaminants, and other impurities from the stainless steel’s surface, restoring the protective passive layer. The process involves several steps, including cleaning, pickling, and rinsing. The cleaning stage eliminates dirt, grease, and oils, while pickling removes impurities and iron residues. Finally, the stainless steel is thoroughly rinsed to eliminate any remaining traces of pickling solution.

Benefits

1. Enhanced Corrosion Resistance: this process ensures the stainless steel maintains its optimal corrosion resistance, extending the material’s lifespan and reducing maintenance costs.
2. Aesthetic Improvement: By removing surface imperfections and stains, it enhances the stainless steel’s appearance, making it more visually appealing.
3. Compliant with Australian Standards: Several Australian standards, such as AS 1627.1, specify the requirements for passivation to ensure the longevity and reliability of stainless steel in different applications.

Why Stainless Steel Corrodes Without Passivation

When the passive layer on stainless steel is damaged or contaminated during manufacturing, the exposed metal becomes susceptible to corrosion. Without proper protection, the active sites on the surface allow corrosion to propagate rapidly. As a result, the stainless steel may develop rust or pitting, compromising its structural integrity and performance.

Passivation plays a crucial role in maintaining the exceptional corrosion resistance of stainless steel and ensuring compliance with Australian standards.

By eliminating surface contaminants and restoring this protective layer, passivation safeguards stainless steel against corrosion, making it a reliable and durable material for various applications.

Engineers, manufacturers, and end-users must recognise the importance of passivation in preserving the longevity and performance of stainless steel in diverse environments, from marine to industrial settings.

Adhering to proper passivation procedures will ensure the continued success of stainless steel as a reliable material in numerous industries.