Speaking about this, what, no steel helmets?
And we come to the problem aforementioned. There were steel helmets of all types, and all were used: French Adrian, Czech helmets... But the star and most used was the Trubia m26 helmet, and it's the iconic steel helmet of the SCW. In both armies. You may see it here:
https://www.lne.es/asturias/2010/11/04/trubia-puso-primeros-cascos/989612.html
But, again, there weren't enough to equip all soldiers. It's only a estimation made after seeing hundreds (thousands?) of photos, but I'd say that only 1 in every 4 was equipped with a helmet.