Mild steel is one of many different grades of steel which are produced internationally. In fact, the World Steel Association claims there are more than 3500 grades of steel when you take into account all of the unique physical, chemical and environmental properties.

These different properties are brought about by varying the different alloying elements mixed with iron in the production of steel. Alloying elements – even carbon – act as hardening agents, preventing dislocations from occurring inside the iron crystals which allow the lattice layers to slide past each other. This is the reason why steel is harder than iron, and why mild steel – which contains a lower amount of carbon than other steels – is a more ductile variety of the material.

Strength

Although all varieties of steel are harder and display higher strength than pure iron, the structural strength of mild steel is not sufficient for it to be used in structural applications or wherever high levels of stress will be placed on it.

This is due to the low carbon content which makes the steel more malleable, however this fact affords mild steel a greater degree of flex which can be advantageous – particularly in applications where flexibility is required and where stronger steels would be too brittle.

Mild steel is suitable for mechanical engineering and general purpose fabrication. Its strength makes it a terrific choice of material for the construction of cages, frames, fencing and in other applications where it will not be subjected to high stress.

Bright mild steel, which is cold finished for an enhanced aesthetic appearance, has tighter sectional tolerances and increased straightness. It has a marked increase in physical strength over standard mild steel which makes it a better choice for more demanding projects.

Malleability

The reduced carbon content of mild steel makes it easier to shape, drill, weld and cut than other, more brittle varieties of steel. It is this reputation for versatility which has led to its remarkable popularity in many industries from the manufacture of household items to structural applications such as fencing, roll cages and semi-permanent structures.

A high level of demand leads to reduced costs, and mild steel is the most widely produced material in the world thanks to the range of projects which can be completed with this material.

Corrosion

Mild steel has a high proportion of iron to carbon, which means that it is very susceptible to corrosion. Corrosion is brought on by exposure to oxygen, moisture or salt and manifests in brownish red deposits on the surface of the material which is commonly referred to as ‘rust’. This rust comes away from the surface of the metal, exposing more of the material to that which is causing it to corrode. Therefore, if left untreated, corrosion in mild steel will eventually lead to the total decay of the material.

It is therefore not suitable for use in marine environments or in other demanding applications, and wherever mild steel is used outside it is recommended that it is protected with paint or by galvanising it. Galvanising is the preferred method of rust prevention in steel. The process bonds a layer of zinc to the outside of the metal with electrolysis, providing an inert protective layer which will not weaken over time unlike paint which may be undermined by water or other external factors.

Grade Designation Systems Symbols

Non-alloy Structural Steels - EN 10025 : part 2 : 2004

S... - Structural SteelE... - Engineering Steel...235... - Minimum yield strength (Reh) in MPa @ 16mm...JR... - Longitudinal Charpy V-notch impacts 27 J @ +20°C...JO... - Longitudinal Charpy V-notch impacts 27 J @ 0°C...J2... - Longitudinal Charpy V-notch impacts 27 J @ -20°C...K2... - Longitudinal Charpy V-notch impacts 40 J @ -20°C...+AR - Supply condition as rolled...+N - Supply condition normalised or normalised rolled...C... - Grade suitable for cold forming...Z... - Grade with improved properties perpendicular to the surface
Normalised/Normalised Rolled Weldable Fine Grain Structural Steels - EN 10025 : part 3 : 2004
S... - Structural steel...275... - Minimum yield strength (Reh) in MPa @ 16mm...N... - Longitudinal Charpy V-notch impacts at a temperature not lower than -20°C...NL... - Longitudinal Charpy V-notch impacts at a temperature not lower than -50°C...Z... - Grade with improved properties perpendicular to the surface
Thermomechanically Rolled Weldable Fine Grain Structural Steels - EN 10025 : part 4 : 2004
S... - Structural steel...275... - Minimum yield strength (Reh) in MPa @ 16mm...M... - Longitudinal Charpy V-notch impacts at a temperature not lower than -20°C...ML... - Longitudinal Charpy V-notch impacts at a temperature not lower than -50°C...Z... - Grade with improved properties perpendicular to the surface
Structural Steels with Improved Atmospheric Corrosion Resistance - also known as Weathering Steels - EN 10025 : part 5 : 2004
S... - Structural steel...355... - Minimum yield strength (Reh) in MPa @ 16mm...J0... - Longitudinal Charpy V-notch impacts 27 J @ 0°C...J2...  - Longitudinal Charpy V-notch impacts 27 J @ -20°C...K2... - Longitudinal Charpy V-notch impacts 40 J @ -20°C...W... - Improved atmospheric corrosion resistance...P... - Greater phosphorous content (grade S355 only)...+AR - Supply condition as rolled...+N - Supply condition normalised or normalised rolled...Z... - Grade with improved properties perpendicular to the surface
Flat Products of High Yield Strength Structural Steels in the Quenched and Tempered Condition - EN 10025 : part 6 : 2004
S... - Structural steel...460... - Minimum yield strength (Reh) in MPa @ 16mm...Q... - Longitudinal Charpy V-notch impacts at a temperature not lower than -20°C...QL... - Longitudinal Charpy V-notch impacts at a temperature not lower than -40°C...QL1... - Longitudinal Charpy V-notch impacts at a temperature not lower than -60°C...Z... - Grade with improved properties perpendicular to the surface

Post By Marc