ASTM E18-2020 pdf free.Standard Test Methods for Rockwell Hardness of Metallic Materials.
Rockwell superficial hardness test-same as the Rock-well hardness test except that smaller preliminary and total testforces are used with a shorter depth scale.Rockwell hardness nunber-a number derived fromthe net increase in the depth of indentation as the force on anindenter is increased from a specified preliminary test force toa specified total test force and then returned to the preliminarytest force.Rockwell hardness machine—a machine capable ofperforming a Rockwell hardness test and/or a Rockwell super-ficial hardness test and displaying the resulting Rockwellhardness number.Rockwell hardness testing machine—a Rockwellhardness machine used for general testing purposes.Rockwell hardness standardizing machine—a Rock-well hardness machine used for the standardization of Rock-well hardness indenters,and for the standardization of Rockwell hardness test blocks. The standardizing machine differsfrom a regular Rockwell hardness testing machine by havingtighter tolerances on certain parameters.Rockwell hardness testing machine that is designed to betransported, carried, set up, and operated by the users,and thatmeasures Rockwell hardness by the Rockwell indentationhardness test principle.
The Rockwell hardness test is an empirical indentationhardness test that can provide useful information about metallicmaterials.This information may correlate to tensile strength,wear resistance, ductility, and other physical characteristics ofmetallic materials， and may be useful in quality control andselection of materials.Rockwell hardness tests are considered satisfactory foracceptance testing of commercial shipments，and have beenused extensively in industry for this purpose.Rockwell hardness testing at a specific location on a partmay not represent the physical characteristics of the whole partor end product.Adherence to this standard test method provides trace-ability to national Rockwell hardness standards except as statedotherwise.
Rockwell Hardness Test Principle The general prin-ciple of the Rockwell indentation hardness test is illustrated inFig.1. The test is divided into three steps of force applicationand removal.
The indenter is brought into contact with the testspecimen,and the preliminary test force Fo is applied.Afterholding the prcliminary test force for a specified dwell time,the baseline depth of indentation is measured.
The force on the indenter is increased at acontrolled rate by the additional test force F,to achieve thetotal test force F. The total test force is held for a specifieddwell time.
The additional test force is removed, returning tothe preliminary test force.After holding the preliminary testforce for a specified dwell time, the final depth of indentationis measured.The Rockwell hardness value is derived from thedifference h in the final and baseline indentation depths whileunder the preliminary test force.The preliminary test force isremoved and the indenter is removed from the test specimen.ASTM E18 pdf download.