Research Scientist
VTT
In early September, MASCOT participated in EUROCORR 2024, the prestigious corrosion conference held at the Palais des Congrès de Paris, France.
The event brought together 1200 participants from 53 countries, representing a diverse array of expertise and perspectives in corrosion science and materials engineering. Social events, including receptions and a conference dinner, at Maison de la Chimie in the heart of Paris on 4 September 2024 contributed to scientific networking in a collaborative atmosphere. Researchers, industry leaders, and academics gathered to share the latest advances, and MASCOT’s contribution stood out with insights aimed at closing the loop of raw materials and chemicals with reliable, environmentally conscious metals that can withstand the harshest conditions.
A 15-minute lecture titled “Pitting corrosion of stainless steels in acids: development of open and covered pits”, by authors Andressa Trentin, Ahmad Mardoukhi, Pekka Pohjanne and Elina Huttunen-Saarivirta, was presented on 2 September 2024 to approximately 70 people including academics, researchers, engineers, and industrialists. The presentation focused on the mechanisms of pitting corrosion in stainless steels exposed to different acidic environments, specifically sulfuric, hydrochloric, and formic acids at pHs of 2.5 and 4.0 under high temperatures of 90°C. The work emphasizes MASCOT’s commitment to enhancing the reliability of stainless steel in aggressive conditions.
Key Takeaways from MASCOT presentation at Eurocorr 2024 were:
– The presentation emphasized the importance of the Pitting Resistance Equivalent Number (PREN), which reflects the compositional percentages of chromium (Cr), molybdenum (Mo), and nitrogen (N) in stainless steel. MASCOT’s study confirmed that higher PRENs (43, 44) provide greater resilience to pitting, particularly in environments with high temperatures and chloride exposure.
– Duplex stainless steels were found more prone to pitting than austenitic grades under the same conditions. The reason lies in the phase-specific differences in PREN values between ferrite and austenite phases.
– A “Russian doll” structure of pits (where pits form in layers of concentric cavities instead of as single cavities) was observed. This structure results from partial “repassivation” at certain critical points, leading to covered pits with smaller pits forming under collapsed lacy layers. Understanding this complex pit morphology is crucial for better predicting material lifespans in aggressive environments.
The MASCOT project is a joint effort by several partners, including VTT Technical Research Centre Ltd (Espoo) and Metso Research Centre (Pori), Finland, dedicated to pushing the boundaries of corrosion science to help industries operate more sustainably.
