Mild steel is the backbone of fabrication. If you're building gates, frames, brackets, trailers, furniture, or any structural steelwork, you'll be choosing between several different mild steel profiles — and making the right choice from the start saves time, money, and re-work.
This guide covers the most common mild steel sections we supply, what each one is best suited for, and how to choose between them.
Mild steel angle iron
Angle iron (also called equal angle or L-section) has an L-shaped cross-section with two equal legs at 90°. It's one of the most versatile structural steel profiles and is found in almost every fabrication workshop.
Best for
- Corner brackets and frame corners
- Shelf supports and racking
- Gate frames and agricultural structures
- Reinforcing joints between flat surfaces
- Mounting brackets and cleats
The 90° profile makes it naturally rigid against bending in two directions, which is why it's so widely used for framing and support work. Available in 3mm and 5mm wall thickness from 13mm x 13mm up to 50mm x 50mm.
Mild steel box section (square hollow section)
Square hollow section (SHS) has a square cross-section with a hollow centre. The closed profile gives it excellent torsional rigidity — resistance to twisting — which makes it significantly stronger than open sections like angle iron for the same weight of steel.
Best for
- Gate posts and gate frames
- Trailer and vehicle body construction
- Structural columns and posts
- Table and furniture legs
- Any application requiring high strength-to-weight ratio
Available in 2.5mm wall thickness from 20mm x 20mm to 50mm x 50mm, and in 5mm wall thickness in 50mm x 50mm and 100mm x 100mm.
Mild steel rectangular box section (RHS)
Rectangular hollow section (RHS) has the same properties as SHS but with a rectangular rather than square profile. The longer dimension gives greater bending resistance in one direction, making it ideal for horizontal beams and lintels.
Best for
- Horizontal beams and joists
- Lintels and headers over openings
- Trailer chassis and floor frames
- Anywhere greater depth than width is structurally useful
Mild steel flat bar
Flat bar is a solid rectangular section — essentially a thick, narrow plate. It has no hollow section and no angular profile, making it the most straightforward of the mild steel sections.
Best for
- Straps, ties, and bracing
- Connection plates between structural members
- Handles, brackets, and guards
- Decorative ironwork and gates
- Reinforcement plates and gussets
Available in thicknesses from 3mm to 12mm and widths from 20mm to 50mm.
Mild steel tube (circular hollow section)
Circular hollow section (CHS) is the round equivalent of box section. Its circular profile gives it the same strength in all directions, making it ideal for posts, columns, and any application where the load can come from any direction.
Best for
- Posts and columns
- Handrails and balustrades
- Axles and rotating components
- Decorative steelwork
Mild steel square bar and round bar
Square bar and round bar are solid sections (no hollow centre) used primarily for shafts, pins, handles, and decorative applications. They are much heavier than hollow sections for the same cross-sectional size, so they're typically used in smaller dimensions or where the solidity is specifically needed.
Fasteners for mild steel fabrication
When assembling mild steel sections, the right fasteners are just as important as the steel itself. For most mild steel fabrication work in sheltered conditions, BZP hex head set screws with matching nuts and washers are suitable. For outdoor or structural applications, use HDG throughout.
- Hex Head Set Screws — BZP and HDG
- Bolt, Nut and Washer Sets — BZP and HDG
- Threaded Rods — for through-rod connections
- Washers — flat, square plate and spring
