During World war I and World war II, head protection was provided by thin steel helmets. Steel was universally used. The technology was simple and cost was low. Although steel Helmets could provide good Impact protection in a variety of situations, then could only provide below marginal or low protection against fragments for their weight. The composite helmets on the other hand offer a lower weight and nearly a 100% improvement in ballistic performance. Composite fibers are upto 6 times as strong as steel on an equal weight basis.
Other comparisons between Steel and Composite Helmets can be noted as below:
helmets 
