| Cast iron generally means grey cast iron, but is | | | | Iron is generally melted in a small blast furnace called |
| identifies a group of ferrous alloys which solidify with a | | | | cupola. After melting is over the melted iron is ladled |
| eutectic. | | | | from the forehearth of blast furnace. This system was |
| Overview: | | | | developed by the Chinese whose innovative ideas |
| Iron accounts for more than 95% the alloy material, | | | | brought revolution in field of metallurgy. Before that iron |
| while the main alloying elements are carbon and silicon. | | | | was melted in an air furnace, which is a type of |
| The amount of carbon in cast iron is 2.1-4% while | | | | reverberatory furnace. |
| ferrous alloys with less carbon are called carbon steel | | | | Some advantages of cast iron in engineering uses:a) A |
| by definition. Cast iron has appreciable amount of | | | | family of metals having capacity of being used for |
| silicon normally 1.3%. Therefore, these alloys should be | | | | engineering and production needs.b) You can have it in |
| considered ternary Fe-C-Si alloys. | | | | a wide range of mechanical and physical properties.c) |
| In spite of this, the principles of cast iron solidification | | | | Good strength to weight ratio.d) Generally cheaper |
| are understood from the binary iron carbon phase | | | | than other competing metals and lower financial cost |
| diagram, where the eutectic point lies at 1154 °C | | | | per unit of strength compared to other metals.e) |
| and 4.3 wt% carbon. Because cast iron has this | | | | Lesser density and higher thermal conductivity then |
| composition, its melting temperature of 1150 to 1200 | | | | steels at comparable tensile strength levels.f) Easily |
| °C is about 300 degrees less than the melting | | | | mechniable, allows high speeds and feeds and less |
| point of pure iron. Cast iron tends to be brittle, though | | | | energy due to free graphite being presence.g) Many |
| the name of particular alloy may suggest opposite. The | | | | iron castings may be utilized without heat treatment |
| color of a fracture surface may be utilized to identify | | | | (as cast) but when required may be heat treated to |
| an alloy; carbide impurities allow cracks to pass straight | | | | increase overall properties or local property like |
| through resulting in a smooth "white" surface, while | | | | surface hardness.h) Very good damping capability |
| graphic flakes deflect a passing crack and initiate | | | | especially in grey irons.i) Chemical analysis may be |
| countless new cracks as the material breaks, leading | | | | changed to give improved special properties like |
| to a rough surface that looks grey with its low melting | | | | corrosion resistance, oxidation and wear resistance.j) |
| point, good fluidity, castability, excellent machinability and | | | | Quickly changes from design to finished goods.k) |
| wear rising resistance, cast irons have become an | | | | Capable of having highly complex sizes from ounces |
| engineering material with a wide range of uses like | | | | to 100 tons.l) Of flexible pattern and capacity to |
| pipes, machine and auto parts. | | | | improve appearance for sales appeal.m) You can |
| Products: | | | | make intricate shapes as well as very thin to very |
| Cast iron is produced by remelting pig iron, normally | | | | thick sections.n) Capable of redesigning and combining |
| with large quantities of scrap iron and steel and initiating | | | | two or more parts from metals into a single casting |
| steps to remove unwanted contaminants like | | | | thereby lessening assembly cost and time.o) Capable |
| phosphorus and sulfur. Depending on use carbon and | | | | of being cast with inserts of other metals.p) Many |
| silicon content are lessened to the required levels | | | | casting systems for low, medium or high production.q) |
| which may be anywhere from 2% to 3.5% and 1% | | | | Less tendency toward residual stress and warpage |
| 3% respectively. Other elements are then added to | | | | than other competing metals. |
| the melt prior to the final form being made by casting. | | | | |