Chapter 20 Elements and Their Properties. Chapter 20 Section 1: Metals.
Metals and Their Properties
-
Upload
mahmoud-eltawab -
Category
Documents
-
view
22 -
download
0
description
Transcript of Metals and Their Properties
Metals and their Properties
Ferrous and Non Ferrous Metals
All metals can be categorized as either Ferrous or Non Ferrous
Ferrous Metals contain ironNon Ferrous Metals do not contain
iron
Examples of Ferrous Metals
Cast IronMild Steel (BDMS)Stainless SteelWrought IronTool Steel High Speed Steel (HSS)
Examples of Non Ferrous Metals
CopperBrassLeadZincAluminiumPewterGold
Pure Metals and Alloys
All metals can be categorized as either a pure metal or an alloy
A pure metal is made of only one type of metal and appears in the Periodic Table of Elements
An alloy is a mixture of metals
Examples of Pure Metals
GoldCopperLeadAluminiumPlatinumZinc
Examples of Alloys
Brass (copper/zinc) Bronze (copper/tin) Stainless Steel
(iron/carbon/nickel/chromium/magnesium Duraluminium (aluminium/copper/manganese) Phosphor Bronze (copper/tin/phosphorous) Bell Metal (80% copper/20% tin) Soft Solder (tin/lead) Pewter (traditionally 80% tin/20% lead) Nickel Silver (copper/zinc/nickel) Naval Brass (63% copper 37% zinc)
Properties of Metals
Tensile Strength Compressive Strength Bending Strength Shear Strength Torsional Strength Elasticity Plasticity Malleability Ductility Hardness Toughness/Brittleness Fatigue Durability
Tensile Strength
Is the ability to resist stretching or pull forces. It is an essential property of all cables chains and ropes
Compressive Strength
Is the ability to withstand a pushing force which tries to crush or shorten
Bending Strength
Is the ability to withstand the forces that attempt to bend a piece of material
Shear Strength
Is the ability to resist strong sliding forces acting opposite to each other
Torsional Strength
Is the ability to withstand twisting forces under torsion or torque
Elasticity
Is the ability to flex and bend when subject to loads and forces, and regain normal shape and size when these are removed (like an elastic band).
Most structures need to possess some degree of elasticity
Plasticity
Is the ability of a material to be changed permanently in shape, by external blows or pressure, without cracking or breaking (e.g. plasticine)
Some materials are more ‘plastic’ when heated
Malleability
Is the extent to which a material can be changed by hammering, pressing or rolling.
Ductility
The ability to undergo deformation by bending, twisting but most usually by stretching into wire
Hardness
Is the ability to resist abrasive wear and indentation
It is an important property of cutting tools like files
Toughness/Brittleness
Is the ability to withstand sudden shock, and the resistance to cracking when subjected to bending and shear forces.
Fatigue
Is caused by repeated stress cycles, bending or tension.
It is found in structures such as aircraft wings
Fatigue is also affected by corrosion
Durability
Is the ability to withstand wear and tear, weathering and corrosion