Metallurgy

CASE STUDIES

MAKING A FIRE-RESISTANT STEEL

Company

TU Delft together with steel manufacturers

Challenge

The twin towers collapsed in 2001 because the steel that kept them standing couldn´t resist the fire. The changes in temperature modified the microstructure of the steel and it lost its strength, making the towers crumble. Knowing what happens inside steel (the nucleation process) when it is submitted to high temperatures could help find a better composition for this alloy.

Sample

Steel.

Solution

3D X-ray diffraction on ID11 has proven a unique technique to track the nucleation process inside steel as it is submitted to temperatures of 1000 C. Scientists came up with a furnace that could be compatible with the beamline and that had temperature control. They found that nucleation, which is a key process in metals, happens quicker than literature had predicted: there are special places, like grain corners or edges in the material where nucleation takes place more easily than other areas. Amongst these corners and edges there are ones that are preferred for nucleation.  Controlling the nucleation means controlling the properties of the material.

Also, the crystals in the steel become coarser at higher temperatures, which decreases the material's strength. Scientists are currently testing the replacement of potentially scarce elements in the alloying process of steel by other elements more widely available.

Benefits

A better “recipe” for steel using less alloying elements would make the material more fire-resistant, less expensive and easier to recycle whilst maintaining its properties. 

Sharma H., et al, Scientific Reports, DOI: 10.1038/srep30860