What Is Rolled Structural Steel?
Rolled structural steel, commonly designated as SM400B or SM490C, is a type of steel material initially developed for shipbuilding. The ‘SM’ stands for ‘steel marine,’ with the numerical values indicating the minimum guaranteed tensile strength and the letters A, B, and C representing different grades, with C being the highest.
There are 11 types of rolled structural steel for welded structures, categorized based on yield point, tensile strength, and chemical composition.
Uses of Rolled Structural Steel
Primarily used for welded components, this steel was initially predominant in ship hulls. Its applications have since expanded to include architecture, social infrastructure, pipelines, industrial machinery, and power generation plants.
Characteristics of Rolled Structural Steel
The range includes SM400A, SM400B, SM400C, SM490A, SM490B, SM490C, SM490YA, SM490YB, SM520B, SM520C, and SM570. While similar in additive composition to general structural steel (SS material), rolled structural steel is made from killed steel, which is deoxidized with substances like silicon or aluminum to enhance toughness at low temperatures. This makes it suitable for use in temperatures from 14°F to 660°F.
Grades B and C are impact-tested steels with guaranteed low-temperature toughness, while Class A offers weather resistance and strength. Class Y is specifically designed for higher yield points, making it ideal for long-term use in bridges and civil engineering applications.