Question

A company specification calls for a steel component to have a minimum tensile strength of 1240 MPa. Tension tests are conducted on selected samples, but all components are also subjected to Vickers hardness testing. (A) What HV (in Kgf/mm2) is the minimum acceptable value? (B) If hardness is measured using Rockwell C hardness test, what is the minimum HRC value that is acceptable?

Answer 1

Answer:

HV = 372.4 KGf/mm^2

$HR_C = 39.445$

Explanation:

given data:

minimum tensile strength = 1240 MPa

we knwo that $\sigma_{vrs}$  and brinell hardness number (HB} relation given as

$\sigma_{vrs} = 3.4 \times H.B$

$H.B = \frac{1240}{3.4} = 364.7$

1) relation betwen H.B and Rockwell is

 $HR_C = 6.96 + 0.089 HB$

 $HR_C = 6.96 + (0.089\times 365} = 39.445$

2) relation between HB  and Vickers hardnes HV is given as

 $HB \times 1.05 = HV + 10.5$

$HV = HB\times 1.05 - 10.5$

HV = 372.4 KGf/mm^2