JASO M 609:2024 Webinar Recap
Blog
Last Updated 2025
Our final webinar of 2025 explored the latest updates to the Japanese automotive corrosion testing standard JASO M 609:2024. This release represents a major and comprehensive revision to the widely-used JASO M 609-91, a pioneering standard that originally introduced cyclic corrosion testing with salt fog, humid, and drying phases, plus rapid transitions between steps.
The History of JASO M 609-91
Originally developed in 1991 by the Japanese Automotive Standards Organization, JASO M 609-91 was designed to evaluate the corrosion resistance of steel sheets used in automotive applications. At the time, existing cyclic corrosion tests did not consistently correlate with real-world exposure, leading to wide variation in testing practices across companies.
To address this, JASO conducted an extensive interlaboratory study involving more than 4,000 specimens. The resulting test method was designed to be accelerated while maintaining correlation to in-service performance, capable of evaluating both cosmetic and perforation corrosion, inclusive of salt fog, drying, and wetting phases, suitable for international interlaboratory comparison, and compatible with commonly available laboratory equipment.
The test cycle incorporated fog, dry, and humid stages with rapid transitions. These fast transitions required more heating capacity than most corrosion test chambers could support at the time. In response to this challenge, Q-Lab introduced Rapid Ramp Heaters in 2020 to enable compliance with the test requirements.
Despite its strengths, JASO M 609-91 had limitations related to reproducibility, repeatability, and long-term correlation. While corrosion standards in the United States and Europe continued to evolve, the Japanese standard remained largely unchanged for over 30 years, making a revision necessary.
JASO M 609:2024 A Modernized Approach to Automotive Testing
The updated standard is based on extensive data collected from real-world outdoor corrosion exposure. Test protocols were evaluated against this data to determine the most representative approaches for inclusion in the new standard.
JASO M 609:2024 introduces three distinct test methods - Methods A, B, and C - all of which differ significantly from the 1991 version. Salt solution concentrations of 5 percent, 1 percent, and 0.5 percent are now all specified. Test cycle temperatures have been revised, and additional exposure techniques are permitted, including shower application in Method B and both shower and immersion in Method C. Method C also specifies an 85 percent relative humidity requirement - the first controlled RH value (not fully dy or fully humid) in a JASO M609 test.
The standard provides expanded guidance on specimen preparation prior to testing, as well as detailed evaluation procedures following exposure for both cosmetic and perforation corrosion. While the new version retains familiar elements such as fog, humid, and dry steps, the overall structure and execution of the test are substantially different. As a result, it is no longer sufficient to reference JASO M 609 alone. The specific version and test method must now be clearly identified.
To stay current on JASO M 609:2024 and other accelerated and outdoor corrosion test standards, visit our Test Standards Page and explore our Standards Search Tool. Contact our team to learn how these updates may impact your testing programs and equipment needs.