Identified content errors were corrected on 2026-10-25. Sources and scope for this page: Dura-Bar 80-55-06 product data (accessed 2026-10-25), covering manufacturer-specific example and test conditions; not a universal property of ductile iron. What the 2026-10-25 correction changed is stated with the source above; nothing beyond that scope was re-checked. How sources, methods and updates are recorded.
Last updated 2026-10-25
Graphite form and grade matter
Gray iron contains flake graphite; ductile iron contains predominantly nodular graphite. Nodules reduce the severe stress-raising effect associated with flakes, but do not eliminate stress concentration or make every ductile iron equally ductile.
There is no family-wide elongation of 12–18%. For example, Dura-Bar’s 80-55-06 product sheet gives 6% minimum elongation for its stated longitudinal test specimen taken at mid-radius of the as-cast bar. Do not transfer that number to other grades, castings or test conditions.
Compare like conditions
Specify grade, product form, matrix or heat treatment, section size and test basis before comparing tensile properties. Machinability and damping cannot be ranked from the words “gray” and “ductile” alone.
Basis and scope
Dura-Bar 80-55-06 product data: Manufacturer-specific example and test conditions; not a universal property of ductile iron.