Development of sheet steel production technology. Report 1. High-strength low-alloy steels (HSLA)

The paper provides an overview of the development of sheet steel production technologies. It was the nascent automotive industry of the early 1900s that ushered in the era of alloy steels. In the early years of automobile production, molding ability and costs were the main determinants of the steels used. The strength of steel was not a particular concern at this time, as thickness was added if additional strength was needed. Early generations of automotive steels were simple C–Mn steels produced using a simple thermomechanical process: continuous cooling immediately after hot rolling of steel in a fully austenitic state. Typical mechanical properties of early generation automotive steels are yield strength up to 250 MPa and tensile strength up to 350 MPa. Steel properties have improved significantly over the last century, from low-carbon steel in the early 1900s to high-strength low-alloy alloys (HSLA) in the late 1970s and the advent of the first generations of improved high-strength steel (AHSS) in the 1990s. It is shown that the improvement in the stampability of sheet steels was the result of a strong demand from automotive companies to increase car production. Technologies that make it possible to produce ultra–low carbon steels are vacuum degassing systems (DH).