STEEL - PROPERTIES AND JOINTS, STAINLESS STEEL

Hi again. 

Before getting into the details of steel, there are some terms that has to be known and how important they are during the selection of the construction materials. 

GALVANIC ACTION : 

Anode and cathode represent the positive and negative energy respectively. When two metals are in contact, the one in the higher side of the galvanic series will become anode and will corrode. Steel is more anodic when compared to copper, bronze, gold. 

CO EFFICIENT OF THERMAL EXPANSION : 

If there is any change in temperature, metals expand and contract. This change is measured with a co efficient which is the ratio between change per length and degree of change. 

SPECIFIC GRAVITY :

It is measured as the ratio between density of the substance and the density of water. 

TENSILE STRENGTH AND YIELD POINT :

Every material undergoes stress and strain. When the material reaches to a point where after that, it would experience deformation, its called the yield point ( high stress ). If the stress is even more, then the tensile strength of material protects it from breaking. After this point, the material experiences necking and finally it fails. 

REFLECTIVITY : 

This shows how much a material can reflect light. 

p(y) = Gr(y)/Gi(y)

p - reflectivity

y - wavelength of light 

Gr - reflected radiation 

Gi - incident radiation

The above properties can be used to differentiate the metals and choose the ones based on requirements and context. Now getting into the joints, there are 2 types : Welding and Mechanical joints 

JOINTS :

Welding / soldering :   using oxygen/acetylene gas mixture or an electric arc

Mechanical joints : Bolt, rivet, pin, mechanical fastener. 

The session ended with the discussion on the types of stainless steel with different properties for different purposes. 

Thanks.

Bye. 

- Nandhini