12x12 Square Solid Bar is a hot rolled mill finish Square shaped solid Mild steel with relatively low tolerance coarse finish bar with mill scale. Mild Steel Square Solid Bar / Rods can be used in all manner of construction and fabrication applications. At THE METAL WAREHOUSE we stock a wide range of mild steel Square bars in 300 grade mild steel. mill scale. Common Uses: - Screens – Grates & Pits – Pins & Axles – Trailers & Truck Bodies – Rustic Furniture & Much More