Mechanical Properties of Nodular Cast Iron

Introduction

Nodular Cast Iron, also referred to as ductile iron or spheroidal graphite iron, is a group of irons in which the graphite forms as nodules (spherical) instead of flakes as in normal cast iron. Nodulizing elements, typically magnesium, are used to allow the solidification of the graphite into nodules. Due to different manufacturing processes a wide range of mechanical properties are observalble, care must be taken when comparing stress-strain or fatigue data.

Stress-strain plots for Nodular Cast Iron

Figure 1: Tension Data. Curve 1: as-cast pearlite nodular iron: 0.1%. Curve 2: high-silicon nodular iron (failed in elastic region at point X). Curve 3: En 4 steel. Curve 4: annealed ferritic nodular iron.

Figure 2: Compression Data. Curve 1: as-cast pearlite nodular iron: 0.1%. Curve 2: high-silicon nodular iron. Curve 3: En 4 steel. Curve 4: annealed ferritic nodular iron.

Fatigue Life plots for Nodular Cast Iron

Figure 2: Fatigue Data. Low hardnness (186 HB). Medium hardness (228 HB). High hardness (270 HB)