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Knowledge of the properties of the metal is an essential aspect of welding engineer’s ability to be a good welding engineer. This knowledge allows the engineer to choose the most suitable material to improve upon the cost and functioning of the component being designed.

Various metals and non-metals are used in fabrication and construction, they all possess certain specific properties that differentiates them from others to be more desirable for the specific demands of the design to be an engineering material. All these metal properties are assessed and classed in three specific metal properties that are relevant to the engineering evaluations, for the suitability for the project.

Metal properties can be classified as,

1 1. Mechanical properties

2 2. Physical properties and

3 3. Corrosion properties.

These are the primary properties however they can also be classified on the basis of their nuclear and optic properties. Further they can be classified on the basis of, if these properties are structure sensitive, or structure insensitive etc. Some details of these properties given the Table 2.1 below.

Table 2.1 Properties of materials.

General group	Structure-insensitive properties	Structure–sensitive properties
Mechanical	Elastic moduli	• Ultimate strength,• Yield strength,• Fatigue strength,• Impact strength,• Hardness,• Ductility,• Elastic limit,• Damping capacity,• Creep strength,• Rupture strength.
Physical	Thermal Expansion,Thermal conductivity,Melting point,Specific heat,Emissivity,Thermal evaporation rate,Density,Vapor pressure,Electrical conductivity,Magnetic properties,Thermionic emission.	Ferromagnetic properties
Corrosion	• Electrochemical potential,• Oxidation resistance	Corrosion of metals does affect some of the mechanical properties leading to metals failures.
Optical	• Color,• Reflectivity.
Nuclear	• Radiation obsorbtivity,• Nuclear cross section,• Wavelength of characteristic X-rays

The following is the discussion on these material properties.