Past 50-Year Development of Constructional Steels

A number of significant advances have been made during the past 50 yr in the technology of steels for constructional applications. Carbon steels have been developed with improved strength, toughness, and weldability. Economical high-strength low-alloy steels are now available with yield strengths in the range of about 42,000 psi to 65,000 psi (290,000 kN/sq m to 449,000 kN/sq m). Steels with superior atmospheric corrosion resistance have been successfully used in the bare (unpainted) condition in major structures. Heat-treated constructional alloy steels have been developed for applications where yield strengths on the order of 100,000 psi (690,000 kN/sq m) are desired. Specialty alloy steels have been developed for applications which require superior combinations of strength and toughness. Careful consideration must be given to selection of steels for a particular application because of the wide range of mechanical properties and metallurgical characteristics now available for structural steels.