The addition of boron to steel allows the achievement of higher strength after hardening by heat treatment, but offers a workable material to the fabricator or manufacturer when in the “as-delivered” condition.
Boron is often added to medium carbon steels to achieve an in-service performance comparable to high carbon and more costly low alloy steels (rather than increasing their carbon and manganese content or adding chromium and molybdenum – with the attendant penalty of reduced ductility during fabrication).
The amount of boron which is added to achieve these characteristics is very small – in the range 0.0005-0.005%.
Traditional applications for boron steels are in wear applications such as shovels/spades, caterpillar tracks, plough shares, punches, but also some spring steels, and more recently in automotive car bodies. Here they have been developed into high strength sheet steels for parts of the body shell and chassis – such as door sills, door pillar reinforcement, cross members, safety beams and bumper reinforcements.