Is there a fundamental unit associated with Rockwell hardnes

Is there a fundamental unit associated with Rockwell hardness number? Explain How may one determine if the specimen was too thin to be checked with a particular Rockwell scale? List three factors that may cause inaccuracy of a hardness test. What are the advantages of Brinell hardness testing over Rockwell hardness testing?

Solution

solution

1) No , there is no fundamental unit associated with rockwell hardness number

3) flatness and surface finish have already been mentioned above but it is worth re-emphasising the point that flatness is most important - a maximum angle of approximately ± 1° would be regarded as acceptable.To achieve the required flatness tolerance and surface finish surface grinding or machining may be necessary. The correct load must be applied and to achieve this there must be no friction in the loading system otherwise the impression will be smaller than expected - regular maintenance and calibration of the machine is therefore essential. The condition of the indentor is crucial - whilst the Vickers diamond is unlikely to deteriorate with use unless it is damaged or loosened in its mounting by clumsy handling, the Brinell ball will deform over a period of time and inaccurate readings will result. This deterioration will be accelerated if a large proportion of the work is on hard materials. The length of time that the load is applied is important and must be controlled.

4) Main advantage of brinell hardness testing is it uses bigger penetrator than rockwell machines and rockwell hardeness tester uses smaller penetrates than the brinell testers.