Rockwell C Scale

The Rockwell C test measures hardness with a diamond cone and a high test load. It's meant for hardened and tempered steels, i.e., parts that need to be really tough and hard. If you're welding, use it to check the base material and the heat-affected zone. If the value is too high, it gets critical when welding, cracks may occur. Too soft means the tempering didn't work. Make sure the test surface is clean and flat, otherwise you'll skew the result. If you're unsure, measure at several spots.