Use of higher strength steel grades
These requirements have led a succession of improvements in existing steel grades but also to the development of new steel grades. For example improvements in steel cleanness have meant that wheel bearings, which used to have to be replaced at regular intervals, now can be expected to last for the life of the vehicle.
However it is the steels used in car bodies where the most striking developments have occurred. Early attempts at reducing vehicle weight go back as far as the Model T Ford with the use of higher strength steels alloyed with vanadium. Over about the last 50 years, the strengths of steels used in automobile bodies have increased by nearly a factor of ten. This had to be achieved whilst maintaining sufficient ductility to allow the materials to be formed into the complex shapes required by designers.
These developments made full use of our understanding of the relationships between microstructure and mechanical properties and are probably the best demonstration of the versatility of the iron-carbon system which forms the basis of steel.