Link to private group:
https://www.skool.com/machine-shop-launchpad/about
Link for Sandvik ISO Chart:
https://www.sandvik.coromant.com/en-us/knowledge/materials/workpiece-materials
Link other ISO Charts:
https://www.meadmetals.com/blog/iso-classifications-for-workpiece-material
https://www.cobanengineering.com/Metal-Cutting-Technology/Work_Parts_Material-3.asp