Class 2 (2nd Engineer) MEKG 📅 Apr 2024

Exam Question

Cast iron is most widely used metal after steel in Marine Engineering. Most cast irons consist of graphite in steel like matrix. Discuss the variation of properties that may arise with reference to pearlitic grey cast iron and spherical grey cast iron. Describe briefly the treatment necessary to produce these two types of Irons. (16)

Reference Answer

### **Introduction**
Cast Iron is a ferrous alloy with a carbon content typically between 2.11% and 4.5%, along with significant amounts of silicon. Its properties are primarily determined by the form and distribution of carbon in the final microstructure. In most cast irons, the excess carbon precipitates as graphite within a steel-like matrix (ferrite, pearlite, or a mixture). The morphology of this graphite—specifically its shape, size, and distribution—is the single most important factor influencing the mechanical properties of the iron. This answer will compare Pearlitic Grey Cast Iron, characterized by flake graphite, with Spherical Graphite (SG) or Ductile Cast Iron, characterized by nodular graphite.
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### **Pearlitic Grey Cast Iron**

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