Cast Iron

Cast iron is a ferrous alloy; the carbon content is greater than the maximum solubility in austenite at the eutectic temperature.

It tends to be brittle, except for malleable cast irons. With its low melting point, good fluidity, castability, excellent machinability and wear resistance, cast irons have become an engineering material with a wide range of applications, including pipes, machine and car parts.

Iron (Fe) accounts for more than 95 %wt of the alloy material, while the main alloying elements are carbon (2.1 to 4 %wt) and silicon (1 to 3 %wt).
Material properties:

Density kg/m37000 to 7400
Modulus of elasticity E GPa83 to 170
Modulus of elasticity G GPa32 to 69
Poisson’s ratio v0.2 to 0.3

Note: These properties should be used for indication only as material properties vary from sample to sample.

Cast iron has many uses: flywheels, cylinder liners, pistons, bedplates.

BS1452 Grade 220 – A continuous cast iron bar, it has a fine grain structure combined with the fine graphite flake size and dense homogeneous structure.

BS1452 Grade 250 – Good combination of wear resistance and strength, reasonable machinability and excellent surface finishes.

BS1452 Grade 260 – A fine grain structure, combined with the fine graphite flake size and dense homogeneous structure. Good wearing characteristics and when components require a combination of strength and wear resistance superior to those of other softer cast iron grades.

Uses: Pistons, moulds, dies, bearings, cams, bushes and gears.

Austenite

Non-magnetic face-centered cubic iron. Also iron and steel alloys that have the face-centered cubic crystal structure.

It is produced by heating steel above the upper critical temperature and has a high solid solubility for carbon and alloying elements. This temperature or temperature range is called the austenitizing temperature and must be attained to obtain the proper microstructure and full hardness of steel in heat treating. The austenitizing temperature varies for the different grades of carbon, alloy and tool steels.

Austenite can dissolve up to 2 percent carbon. Austenite is relatively soft, ductile and nonmagnetic.

Angle Iron

An iron or steel structural member that has been cast, rolled, or folded so that its cross section is L-shaped.

Cast Iron Dust

cast iron dust

Breathing cast iron dust can be harmful, some simple precautions such as a face mask are sensible.

Gears

All types of cast iron, from gray to ductile, reduce noise because of the inherent damping properties of the metal.

Gears that are subject to high impact forces may not be suitable for ductile iron. Converting to ductile iron is not recommended in cases where added strength is required because of fatigue failures.

Iron

One of the most important and used on the largest scale of any metal.

  • Symbol: Fe from the Latin name ferrum
  • 1400BC iron working is developed in the Middle East.
  • One of the most abundant metals, 41000 ppm in the earth’s crust.
  • Produced in the blast furnace.
  • Essential element for all life forms, the average human body contains 4g of the element.

Pure iron can exist in three forms:

  • Alpha iron is a polymorphic form of iron which is stable below 906°C. Has a body centred cubic lattice (bcc) and is magnetic up to 768°C.
  • Gamma iron is a polymorphic form of iron which is stable between 906°C and 1403°C. Has a face centred cubic lattice (fcc) and is nonmagnetic.
  • Delta iron is the polymorphic form of iron which is stable between 1403°C and the melting point. Has the same lattice structure as alpha iron.

6mm tungsten carbide glanze lathe tool

Machining Cast Iron

Machining cast iron can be quite easy with the right tools, but you do have to be careful with cast iron that might have sand still in the surface and so I thought a page giving hints and tips would be useful.

Pig Iron

The intermediate product of smelting iron ore with a high-carbon fuel such as coke, usually with limestone as a flux. Generally applied to a metallic product that contains over 90% iron. Typically it contains approximately 3% carbon, 1.5% silicon and lesser amounts of manganese, sulfur and phosphorus.

Pig iron along with scrap metal is the base material for both cast iron and cast steel.

Rust

A corrosion product consisting of hydrated oxides of iron. This term is only applied to ferrous alloys. Resulting from exposure to humid atmosphere or chemical attack.

Wrought Iron

The purest commercial form of iron, nearly free of carbon. Contains less than 0.3% carbon and 1.0 or 2.0% slag, giving it ductility and toughness. Other properties are more rust resistant than steel and more easily welded.

About Nigel 326 Articles
I've been making models since I was around 7 years old and using a lathe from the age of 11, a self taught engineer with a passion for making model engines.

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