布氏硬度计洛氏硬度计维氏硬度计三用的洛氏硬度示值允许误差表 ？

硬度标尺

标准块的硬度范围

硬度计示值允许误差

HRA

20_～≤75HRA

±2HRA

>75_～≤88HRA

±1.5HRA

HRB

20_～≤45HRB

±4HRB

>45_～≤80HRB

±3HRB

>80_～≤100HRB

±2HRB

HRC

20_～≤70HRC

±1.5HRC