The spacing between indentations should be three to five times the diameter of the indentation. This test shall utilize the same specimen used in Part I of this experiment. Each of the hardness testers shall be verified for accuracy by use of a calibration block to be supplied by the instructor. If the test data does not fall within the scale of the particular Rockwell scale selected for the test, select another Rockwell scale and repeat the test. The test shall also be repeated on another Rockwell scale if the hardness values rise above 100 or drop below 20 because these extremes of the hardness scale are not very accurate.
Analysis Determine an average hardness number of each test specimen.
Not all of the scales will correspond with the base hardness number established by test. You may combine both Part I and Part II in the same Letter Report .