2.9K views · 138 reactions | Testing the hardness of some 4140 square stock for Rockwell C scale. I’m using it to machine a custom tool for a customer. After machining I’ll use the Hot Shot 360 to heat treat it. #hardnesstester #4140 #abom79 | Abom79 | Facebook

The Rockwell scale is a hardness scale based on indentation hardness of a material. ... The result is a dimensionless number noted as HRA, HRB, HRC, etc., where the last letter is the respective Rockwell scale (see below). When testing metals, indentation hardness correlates linearly with tensile strength. | QA QC Professionals | Facebook