The mechanical properties of steel are described below.
Yield Strength
The point at which steel begins to permanently deform under load. Any deformation beyond this point is permanent.
Points (a) and (b) above show the upper and lower yield strength. It is difficult to define the exact yield strength, so the minimum yield strength is generally defined based on a 0.2% strain offset as shown in the figure above.
※ What is the Yield Strength of Steel? How is it Measured? Difference with the Tensile Strength
Tensile Strength
This is the maximum possible strength that the steel can resist/achieve before deforming further and failing. In the graph above, it would be defined as point (c).
※ What is the Tensile Strength of Steel? How is it Measured? Difference with the Yield Strength
Elasticity
The ability of steel to return to its original shape after being deformed. This is quantified using the Elastic Modulus (also known as Young's Modulus), defined as the steel stress divided by the strain, as it just the slope of the initial line from (0,0) to point (a).
※ What is the Elasticity of Steel?
Poisson's Ratio
When a steel cylinder is loaded in compression, it doesn't just shorten in length, but also expands sideways. The ratio of the sideways expansion to the shortening in length is known as the Poisson's Ratio. For structural steel, it is generally taken as around 0.3.
※ What is the Poisson's Ratio? Explained in 1-minute
※ What is the Poisson's Ratio of Steel?
Ductility
The ability of steel to deform without failing. This can be described as the area underneath the steel stress-strain curve, as shown above.
※ What is the Ductility of Steel? How is it Measured?
Hardness
The resistance of steel to deformation or wear.
※ What is the Hardness of Steel? How is it Measured? Difference with Toughness
Toughness
The ability of steel to absorb energy and resist cracking or breaking.
※ What is the Toughness of Steel? How is it measured? Difference with Hardness
Fatigue Strength
The ability of steel to withstand repeated loading without failure.
※ What is the Fatigue Strength of Steel? How is it measured?
Impact Resistance
The ability of steel to withstand sudden impacts without breaking.
※ What is the Impact Resistance of Steel? How is it Measured? Difference with Hardness and Toughness
Elongation
< coming soon >