Metals Testing Data

Data sets for the four test specimens $($cast iron, mild steel, high strength steel and aluminium$)$ tested during the labs on Thursday $11$th April $2024$ will be uploaded to canvas. The data will be corrected for slack in the crossheads. The data is presented in tabular form in an Excel spreadsheet as extension in mm as a function of force in kN $(103$ N$).$ Using the data:

$($i$)$ Compute and plot engineering stress versus engineering strain. Label the axes correctly using the correct units $($as appropriate$).(4$ marks$)$

$($ii$)$ Determine the modulus of elasticity. $(2$ marks$)$

$($iii$)$ Determine the yield strength or the proof strength at $0\mathrm{.}1\%$ strain offset. $(4$ marks$)$

$($iv$)$ Determine the ultimate tensile strength. $(2$ marks$)$

$($v$)$ Use the stress$-$strain curve to determine the elastic recovery. Quote the elastic recovery in terms of strain. $(4$ marks$)$

$($vi$)$ Use the stress$-$strain curve to determine the ductility. Quote the ductility in terms of strain. $(2$ marks$)$

$($vii$)$ Place the four metals in order of toughness. Demonstrate the order by calculation. $(2$ marks$)$

Show working and tabulate your data $($tabulate answers $($ii$)$ to $($vi$)).$ Ensure that your answers include the correct units $($unless dimensionless$).$

Note the gauge length of the extensometer is $50$ mm$.$ Use this value to calculate engineering strain for the data in the attach spreadsheet.

Initial Diameter $/$ mm

Mild Steel $12\mathrm{.}25$

High Strength Steel

$(4140$ Steel$)12\mathrm{.}12$

Cast Iron $9\mathrm{.}77$

Aluminium $9\mathrm{.}84$