## Estimating Hardness

If a plain carbon steel test specimen has a tensile strength of 50 MPa, estimate the Brinell hardness.

##
__
__**Hint**

**Hint**

The relationship between hardness and tensile strength is roughly:

$$$TS\:(MPa)\simeq 3.5\:HB$$$

where
$$TS$$
is the tensile strength in MPa, and
$$HB$$
is the Brinell hardness number.

##
__
__**Hint 2**

**Hint 2**

Divide the tensile strength in the problem statement by 3.5.

For plain carbon steels, the relationship between hardness and tensile strength is roughly:

$$$TS\:(MPa)\simeq 3.5\:HB$$$

where
$$TS$$
is the tensile strength in MPa, and
$$HB$$
is the Brinell hardness number.

$$$HB\simeq \frac{50\:MPa}{3.5}\simeq 14.3$$$

Note the units for HB are in psi or kg/mm^2 (Pascals), but the results are usually reported unitless.

$$$\simeq 14.3$$$