technical FAQ
The hidden corrosion risk in laser-cut stainless steel
There is no such thing as a bad question - only opportunities for deeper understanding. In Sassda’s training sessions, participants from all levels of the industry regularly raise insightful queries, some of which may seem simple at first but often lead to a clearer grasp of complex, technical concepts. These questions not only benefit those in the immediate training environment but also provide valuable learning for students and professionals across the stainless steel value chain. Over time, we’ve noticed that certain questions come up repeatedly during and after our courses. In this new series we aim to explore some of the most common and thought-provoking questions we receive…
The question? Why do the shiny cutting edges of laser-cut parts corrode preferentially?
The answer... This is not only a frequently asked question during our training courses but a common topic when assisting the industry with technical issues. In this particular instance, the question arose from repeated instances where stainless steel signage for outdoor applications in coastal areas - ordered from reputable laser-cutting service providers - began to show localised corrosion near and around laser-cut surfaces. In all cases, the material used was the austenitic Grade 304, which generally has high corrosion resistance. While Grade 304 might not be the best choice for coastal environments, the fact that corrosion occurs preferentially near the cutting surfaces, is an interesting phenomenon.
The returned pieces were tested, and the material grade was confirmed. A photo sent later, by the student who first raised the question, showed a smooth (2B) finish, eliminating surface finish as a contributing factor to corrosion. This is not an isolated problem; it occurs because the cutting surfaces are not passivated, making them more prone to corrosion. The student countered that the surfaces must have been passivated because they appeared shiny upon receipt of the finished product. When stainless steel is laser-cut, it undergoes a thermal process. The laser beam heats the material to its melting point, although in a highly localised area. This creates a narrow Heat-Affected Zone (HAZ), which is difficult to detect with the naked eye but follows the same principles as
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Issue 1 – 2025
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