6 Key Main Differences Between ASTM A380 vs A967 Passivation Processes

The stainless steel passivation process is an important chemical treatment that enhances the corrosion resistance of stainless steel by removing free iron and other contaminants from its surface. Two primary standards govern this process: ASTM A380 and ASTM A967. While both address the passivation of stainless steel, they differ significantly in scope and application. 

In this article, we’ll consider six key distinctions between these standards. 

1. Scope And Focus 

The ASTM A380 standard provides comprehensive guidance on the cleaning, descaling, and passivation of stainless steel. Its primary emphasis is on pre-treatment processes, ensuring that surfaces are adequately prepared before passivation commences. In contrast, ASTM A967 focuses specifically on the chemical passivation treatments for stainless steel parts, detailing the procedures and requirements for effective passivation.

2. Cleaning Methods 

ASTM A380 outlines approximately 11 different methods for cleaning stainless steel, including the use of alkaline solutions, detergents, acids, steam cleaning, and ultrasonic cleaning. ASTM A967, however, does not delve into cleaning methods, but simply focuses on the passivation treatments themselves. 

3. Passivation Treatments 

ASTM A380 offers a condensed section on passivation, recommending specific solutions tailored to particular steel grades, while the ASTM A967 standard provides detailed descriptions of various passivation treatments, notably nitric and citric acid options. 

4. Verification Tests 

Verification tests are crucial for ensuring passivation treatments are effective. Both ASTM A380 and ASTM A967 provide key guidance, with some overlap in their test methods; three of A967's seven tests are also in A380. 

A380 primarily focuses on cleanliness after passivation, assessing surface finish to confirm contaminant removal. In contrast, A967's seven qualitative tests specifically verify successful passivation by accelerating corrosion to identify ferrous contaminants. These tests include salt spray, high humidity, hot water immersion, and ferroxyl testing, all designed to reveal any underlying iron particles that could compromise the passive layer. 

5. Global Recognition 

Quality standards offer greater reassurance when you know that they are respected across multiple countries or industries. ASTM A967 is a globally recognised standard that is adopted across various sectors for stainless steel passivation. While ASTM A380 is also recognised across the world, some countries or regions also have their own equivalent or comparable standards for the passivation of stainless steel. 

Speak To The Experts At Inox Passivation 

Still confused about ASTM A380 vs A967? At Inox Passivation, our experts can help by providing incisive information and support so that you choose the best passivation treatments for your business’s needs. To find out more, please get in touch today.