A group of commodity steel shapes that consist of rounds, squares, flats, strips, angles, and channels, which fabricators, steel service centers and manufacturers cut, bend and shape into products. Merchant products require more specialized processing than reinforcing bar.

Most pig iron is produced in blast furnaces for subsequent steelmaking at integrated steelworks, and is transferred as molten iron from BF to nearby oxygen converters. But a much smaller tonnage is produced for sale as a steelmaking or foundry raw material. This merchant pig iron is mostly made in coke or charcoal fuelled BFs and sold as ingot. Pig iron is a supplement to ferrous scrap in the EAF, and may be used instead of, or in addition to direct reduced iron or hot briquetted iron in order to make higher grades of steel that may not be achievable using only scrap.

Mild steel is a low carbon steel that is also often referred to as soft steel. It usually has a carbon content which is under 0.25%.

Mill scale forms on the surface of steel when oxygen reacts with very hot metal to form iron oxides. This occurs immediately after casting, and during reheating and hot rolling. The scale, which can range in size from a few microns to several centimetres across, has to be removed, otherwise it will damage the surface finish of the steel during any subsequent rolling. High pressure water jets are used to blast away the scale, and on a hot strip mill this occurs as the steel passes down the run-out table from the roughing mill.

Normally defined as steel mills that melt scrap metal to produce commodity products. Although the mini-mills are subject to the same steel processing requirements after the caster as the integrated steel companies, they differ greatly in regard to their minimum efficient size, labour relations, product markets, and management style.

An alloying element used as a raw material for some classes of stainless steel. Molybdenum in the presence of chromium enhances the corrosion resistance of stainless steel.