Solving Hall-Petch Equation Homework

[TyErd]

Homework Statement

I've attached the question.

Homework Equations

σy = σo + k(d^-(1/2))

The Attempt at a Solution

450 x 10^6 =σo + k / sqrt(17 x 10^-6)-------------1
565 x 10^6 =σo + k / sqrt (0.8 x 10^-6)------------2

σo = 4.18142 x 10^8 Pa and k = 131354

is that right for the first part?

the second part: σy =4.18142 x 10^8 + 131354 / sqrt(0.2 x 10^-6)

σy = 7.11858 x 10^-6 Pa

is that correct?

 

[Spinnor]

Homework Statement

I've attached the question.

Homework Equations

σy = σo + k(d^-(1/2))

The Attempt at a Solution

450 x 10^6 =σo + k / sqrt(17 x 10^-6)-------------1
565 x 10^6 =σo + k / sqrt (0.8 x 10^-6)------------2

σo = 4.18142 x 10^8 Pa and k = 131354

is that right for the first part?

the second part: σy =4.18142 x 10^8 + 131354 / sqrt(0.2 x 10^-6)

σy = 7.11858 x 10^-6 Pa

is that correct?

I got the same numbers for the first part and for the second part I think you are off by a factor of one hundred?

 

[lewando]

I think the strength of titanium is on the order of MPa, not μPa.

 

[Spinnor]

I think the strength of titanium is on the order of MPa, not μPa.

Did not notice the minus sign, the second answer I got was about σy = 7.1 x 10^8 Pa