Question

A part made from annealed AISI 1018 steel undergoes a 20 percent cold-work operation. Obtain the yield strength and ultimate strength before and after the cold-work operation.

Answer 1

yield strength before cold work = 370 MPa

yield strength after cold work = 437.87 MPa

ultimate strength before cold work = 440 MPa

ultimate strength after cold work = 550 MPa

Step-by-step explanation:

given data

AISI 1018 steel

cold work factor W = 20% = 0.20

to find out

yield strength and ultimate strength before and after the cold-work operation

solution

we know the properties of AISI 1018 steel is

yield strength σy = 370 MPa

ultimate tensile strength σu = 440 MPa

strength coefficient K = 600 MPa

strain hardness n = 0.21

so true strain is here ∈ =
`ln(1)/(1-0.2)` = 0.223

so

yield strength after cold is

yield strength =
`K \varepsilon ^n`

yield strength =
`600*0.223^{0.21)`

yield strength after cold work = 437.87 MPa

and

ultimate strength after cold work is

ultimate strength =
`(\sigma u)/(1-W)`

ultimate strength =
`(440)/(1-0.2)`

ultimate strength after cold work = 550 MPa