IS 1865 covers ductile (SG/nodular) iron castings — stronger and more ductile than grey iron (IS 210) due to spheroidal graphite structure. Six grades from 400/18 (ductile, good machinability) to 800/2 (high strength, wear resistant). Used for DI pipe fittings, valve bodies, automotive parts, and manhole covers.
Specification for ductile (nodular/SG) iron castings covering grades based on tensile strength and elongation, chemical composition, heat treatment, and testing.
Key Values
Grade 400/18 tensileMin 400 MPa
Grade 400/18 elongationMin 18%
Grade 500/7 tensileMin 500 MPa
Practical Notes
! Grade designation: first number = min tensile (MPa), second = min elongation (%). So 400/18 = 400 MPa tensile, 18% elongation.
! Grade 400/18 is the most commonly used grade — good combination of strength, ductility, and machinability.
! DI is much stronger and more ductile than grey iron — Grade 400/18 DI has 2× the tensile strength of FG 200 grey iron.
! Nodularity must be >80% — low nodularity means graphite is flake-shaped (behaves like grey iron, loses ductility).
! DI pipe fittings (bends, tees, valves) per IS 9523 are cast from IS 1865 Grade 400/18.