Question

Two samples of a low hardness steel were tested using a Rockwell C hardness tester and the Rockwell B scale at the same lab on the same day . The difference between the average hardness of the two samples was 0.5 Rockwell C. Do you think there is a significant difference in the hardness? Justify your answer. Hint: Use the specification!!

Answer 1

Rockwell hardness tester is used with different scales i.e. B scale and C scale. B scale is used for low hardness materials using a steel ball indenter using 100 kgf load. C scale is used for harder materials using a diamond cone indenter using 150 kgf load. As the above mentioned two samples were of low hardness steel so they must be tested using using Rockwell B scale only. But even if we have tested these samples on both B scale and as well as C scale then we must analyze the relation between the two scales.

As the diiference between the hardness of the two samples was only 0.5 HRC. So it can be said that there is minimum differenece between the hardness of the two samples.

JUSTIFICATION:-

Because if we refer the standard hardness conversion table for steel materials then we can find out that there is no difference in HRB value for a difference of 0.5 HRC. Even up to difference of 1 HRC there is no diffrence in the value of HRB. So it can be concluded with confidennce that there is no significant difference between in the hardness of the two samples in actual.