... of facial hair and light rolling 1,the hardness of the uniformity between concentrated in the 1-3HSD, basically in line with normal ... distribution. 2,Away from the roller surface 40 - 65mm depth range, the hardness of landing roll not more than ... hardness drop, even if used in the late, still has goodwear resistance, through the wear test, the wear resistance of high speed steelmaterials to ...