Fluid steel or fluid compressed steel is a different breed of cat.

The problem is to offset the thermal contraction as steel passes from a liquid to the solid state.

If you pour molten steel into a cruicible, then let it cool, the steel forms a funnel shaped vortex in the center of the cast mass. Aside from the void in the center, the steel has an open crystalline structure because of the thermal contraction.

It was learned in the 19th century that if you pour the molten steel into a crucible with collapsible sides, and as the steel solidifies, you compress the sides of the crucible with hydralic cylinders, the steel is compacted so as to have no void, and the crystalline structure is more dense. The result is a much stronger steel. This was "fluid compressed steel".

The concept caught on throughout the advanced world, and it remains in practice today.

Curl