Heavy Melting Steel (HMS) is a grade of recycled steel scrap. It's a key raw material for steel mills, particularly those that use electric arc furnaces. The term "heavy" refers to the thickness of the material, which is typically at least 1/4 inch (6 mm) or more. This type of scrap is a mix of wrought iron and steel and is often sourced from old structures, pipes, railways, and machinery. It's highly valued for its high density and known composition, which makes it easy for mills to manage and melt down to produce new steel.