What are the differences in thermal expansion between cast iron and stainless steel?

Thermal expansion is a critical property in materials engineering, especially when selecting metals for high-temperature applications. Cast iron and stainless steel exhibit distinct differences in their thermal expansion behaviors due to their unique compositions and microstructures.

Cast iron, primarily composed of iron and carbon, has a lower coefficient of thermal expansion (CTE) compared to stainless steel. The CTE for cast iron typically ranges between 10-12 × 10⁻⁶/°C, making it more stable under thermal stress. This property makes cast iron suitable for applications like engine blocks and heavy machinery, where dimensional stability is crucial.

Stainless steel, an alloy of iron, chromium, and other elements, has a higher CTE, usually between 16-18 × 10⁻⁶/°C. This higher expansion rate is due to its austenitic or ferritic structures, which are less resistant to thermal deformation. Stainless steel is often used in environments requiring corrosion resistance, such as kitchen appliances or chemical processing equipment, where thermal expansion must be carefully managed.

Understanding these differences helps engineers and designers select the right material for specific thermal conditions, ensuring performance and longevity.