What's the expansion rate of stainless steel outdoor planters in direct sunlight?

Stainless steel outdoor planters are popular for their durability and sleek appearance, but their performance under direct sunlight raises questions about thermal expansion. The expansion rate of stainless steel depends on its grade, but generally, it expands at approximately 16.0–18.0 µm/m·°C (micrometers per meter per degree Celsius).

When exposed to intense sunlight, stainless steel planters can heat up significantly, causing measurable expansion. For example, a 1-meter-long planter exposed to a 30°C temperature increase may expand by 0.48–0.54 mm. While this expansion is minimal, repeated heating and cooling cycles can stress welded joints or fasteners over time.

To mitigate risks, choose high-quality 304 or 316 stainless steel, which resists warping and corrosion. Proper design, such as allowing slight movement or using expansion joints, can also enhance longevity. Understanding these factors ensures your stainless steel planters remain functional and visually appealing in outdoor settings.