Mild steel products

IS 2062 chemical composition

Sub-grades A, BR, B0 and C differ in impact-test requirements and some limits; sub-grade C has lower sulphur and phosphorus. See IS 2062 for full requirements.

The carbon equivalent limit ensures good weldability; E250 can normally be welded without preheat in common thicknesses.

IS 2062 mechanical properties

Values for plates, sections, flats and bars to IS 2062.

The grade number is the minimum yield strength in MPa for thinner sections. E350 allows lighter structures for the same load, and E410 and higher grades are available for heavier structures on enquiry.

IS 2062 sub-grades

• A – no impact test; for general structures not subject to dynamic loads.
• BR – impact tested at room temperature (optional).
• B0 – impact tested at 0 °C; for structures subject to moderate dynamic loads.
• C – impact tested at −20 °C, fully killed, lower sulphur and phosphorus; for critical and low-temperature structures.

The sub-grade should match the design – for example, B0 or C for crane girders, bridges and cold-climate structures.

Equivalent grades

Equivalents are approximate; strength, impact and chemistry requirements differ between standards, so material should be certified to the standard named in the design.

Where mild steel is used

Mild steel is used for industrial buildings, sheds and warehouses, pipe racks and equipment structures, platforms, stairs and handrails, tanks and silos, machine bases and skids, conveyor and crane structures, transmission towers, base plates and general fabrication. MS pipes are used for water, gas, air, firefighting and structural purposes. Where corrosion or temperature rule out mild steel, stainless steel or pressure-vessel grades such as A516 are used – see the materials page.

Protection and fabrication

Mild steel rusts when exposed to moisture, so it is painted, galvanised or otherwise coated. Hot-dip galvanising gives long life outdoors; paint systems are chosen for the environment. Mild steel cuts, drills, bends and welds easily with standard equipment and consumables, which is why it is the default material for structures and fabrication.

Choosing the right MS product

For structures, the choice of section depends on the load and span: angles for bracing, frames and light members; channels for purlins, girts and bases; beams for floor beams, girders and columns; and flats for base plates, cleats and stiffeners. Plates are used for base plates, gussets, tanks and fabricated members, and sheets for cladding, ducting and enclosures. MS pipes serve both as fluid-carrying pipes (water, air, gas, firefighting) and as structural hollow sections for columns, handrails and scaffolding.

Where structures will be welded and loaded dynamically, or used in cold climates, specify an impact-tested sub-grade (B0 or C). For higher loads, E350 or E410 reduces weight. For pressure equipment such as boilers and pressure vessels, IS 2062 mild steel is not used; pressure-vessel grades such as IS 2002 or ASTM A516 are specified instead.

Mild steel vs stainless steel

Mild steel is far cheaper than stainless steel and easier to cut, drill and weld, but it rusts unless protected. Stainless steel needs no coating and lasts longer in corrosive and hygienic environments. Over the life of a structure, stainless steel can be more economical where repainting is difficult or contamination is unacceptable – for example in food plants, coastal structures and water treatment. Many plants use mild steel for main structures and stainless steel for parts in contact with product or exposed to corrosive spray.

Ordering mild steel

Please give the product, section designation or dimensions, grade and sub-grade, length, quantity, finish (black, primed, painted or galvanised) and any testing or inspection requirement. Material is supplied with mill test certificates showing the heat number, chemistry and mechanical properties.

Documents

Material is supplied with mill test certificates (MTC) showing heat number, chemical composition and mechanical properties. Third-party inspection is available on request.