Nodularity Measurement of Ductile Iron

Learn how to use image analysis for materials characterization of cast iron.

High ductility makes ductile iron suitable for the manufacture of safety-critical parts such as axles, crankshafts, hubs, brake calipers, transmission parts, and valves. To achieve high ductility, the as-cast structure of ductile iron contains graphite particles in a small, rounded form, often referred to as spheroidal, globular, or nodular. 

The mechanical and physical properties depend on the graphite being predominantly or wholly in the spheroidal (nodular) shape. While visual estimation of nodularity and nodule count has been a long-standing practice, it suffers a major setback of poor reproducibility and repeatability. Image analysis per ASTM E2567-16a provides accurate and repeatable results regardless of the operator, with results obtained in a few minutes.

Key topics covered in this webinar include:

- How the percentage of graphite in the form of nodules (% nodularity) in the matrix of ductile iron (nodular cast iron) controls the mechanical properties of ductile iron
- How to qualify the heat by using percentage of nodularity instead of waiting for mechanical property results
- Using image analysis to measure nodularity and deliver results to the shop floor in a timely manner
- Employing the method’s special features to remove human bias and ensure repeatability