Carbon Steel, Alloy & HSLA Steel Plate Supplier Leeco Steel is a supplier of carbon steel, HSLA and alloy steel plate from the premier mills worldwide. Our inventory of extra-high-strength and abrasion-resistant steels is one of the nation's largest, including nonstandard lengths and thicknesses in both metric and imperial measurements. For over a century we've built our valued reputation as a carbon steel, alloy & HSLA steel plate supplier on availability of inventory, exceptional quality control, efficient large-scale processing capabilities, expert service, and on time delivery. Our stocking facilities are strategically located on riverways and rail lines, close to producing mills and our customers, which reduces freight costs and enables just-in-time delivery.