EN-GJV-400 | 5.2201

Vermicular graphite owes its name to the vermicular structure of the graphite. At least 80 % of the graphite must be in vermicular form, the rest in spherical form (no lamellar form!). Vermicular graphite cast iron is standardized in DIN EN 16079:2013. The grades EN-GJV-300 to EN-GJV-450 are classified according to their tensile strength.

The component in question is nominally made of GJV-400, but has different microstructures in different areas depending on the local wall thickness. With a thin wall thickness and correspondingly rapid cooling, both an increased spheroidal content and a higher perlite content are achieved, which locally ensures a significantly higher strength than 400 MPa.

• Position A: thick wall thickness
  In position A, approx. 87 % of the graphite is present as vermicular graphite (form III),
  7 % is in spherical form (form VI) and 6 % is slightly non-uniform spheroidal graphite (form V).
  The matrix consists of about 50 % ferrite and 50 % perlite.
• Position B: average wall thickness
  In position B, approx. 90 % of the graphite is vermicular graphite (form III), 4 % is spherical graphite (form VI) and 6 % is slightly non-uniform spherical graphite (form V).
  The matrix is pearlitic with approx. 20 % ferrite, which surrounds the graphite worms and spheres.
• Position C: thin wall thickness
  In position C, approx. 87 % of the graphite is vermicular graphite (form III), 5 % is spheroidal graphite (form VI) and 7 % is slightly non-uniform spheroidal graphite (form V).
  The matrix is almost purely pearlitic with approx. 5 % ferrite.
• Position D: White solidification at the edge
  White solidification has taken place locally in an edge zone.
  There is very little vermicular graphite between the graphite spheres; instead, the carbon is present in the form of cementite (Fe₃C).