Metals Unit 212/255 – Principles of Fabrication and Welding Technology

Ferrous Metals Ferrous metals contain iron (Fe). Pure iron is a relatively weak material and not suitable for modern engineering products. The addition of small amounts of carbon (C) produces steel. Steel is the most widely used engineering material.

Steel Steel is an alloy (mixture) of iron and carbon. The percentage of carbon influences the properties of the steel. Other metals can be added in small amounts to change steel properties further. This group of metals are known as alloy steels.

Steel Low carbon steel (LCS): –contains up to 0.29% carbon –is easily welded by a range of processes –is easily formed into a range of shapes –is sometimes known as mild steel.

Steel Medium carbon steel (MCS): –is harder and stronger than LCS –contains from 0.3% to 0.54 carbon –can be welded by a range of processes –can be formed into a range of shapes –may require post-production heat treatment.

Steel High carbon steel (HCS): –Hardest of the carbon steels –Hardness levels lead to a brittle material –Contains from 0.55% to 1.2% carbon –Difficult to weld –Can not be formed due to brittleness. –May need to be annealed prior to machining –Post production hardening and tempering may be required

Galvanised Steel Galvanising is a coating of zinc applied to steel. Most commonly applied by a hot dip method where the steel is submerged in a tank of molten zinc Galvanising prevents rusting of the steel component.

Stainless Steels Stainless steels are commonly used for their corrosion resistance properties. Stainless steels contain a minimum of 10.5% chromium Other metals can be added to improve properties including: Nickel Molybdenum Titanium Copper.

Austenitic Stainless Steel Austenitic stainless steels have good ductility and high strength compared to carbon steels. Welding causes little or no effect on the material properties. Austenitic stainless steels contain nickel. Non magnetic.

Aluminium Pure aluminium is a light metal, approximately ⅓ the density of steel Non magnetic Corrosion resistant due to a naturally produced oxide layer. Good conductor of heat and electricity The addition of copper as an alloy can increase the strength of aluminium to that approaching steel

Forms of Supply Metals are supplied in a wide range of forms. Forms usually describe the shape of the metal.

Forms of Supply Plates or sheet –Usually supplied in rectangular forms –Common sizes are: 2 m x 1 m; 2.5 m x 1.25 m Sheets have thickness up to 3 mm Plates have thicknesses above 3 mm

Forms of Supply Angle iron –Available in equal or un-equal leg lengths

Forms of Supply Hollow section –Available in a range of shapes. Rectangular hollow sectionSquare hollow section

Forms of Supply Hollow section –Available in a range of shapes. Square hollow section Rectangular hollow section is available in a range of sizes. Rectangular hollow section

Forms of Supply Hollow section –Available in a range of shapes. Round hollow section Round hollow section is also known as pipe or tube. Tubing is a structural member. Its outside diameter and wall thickness is important. Pipe is used to convey fluids or gases so the internal diameter is important.

Forms of Supply Channel Steel beams Tee section Flat bar