Consider an $18-8$ Mo steel component $($Animated Figure $9\mathrm{.}41)$ that is exposed to a temperature of $75$Consider an $18-8$ Mo steel component $($Animated Figure $9\mathrm{.}41)$ that is exposed to a temperature of $750C(1023K).$ What is the

maximum allowable stress level for a rupture lifetime of

$($a$)1$ year?

MPa

$($b$)15$ years?

MPa$0^$C$(973$K$).$ What is the maximum allowable stress level for a rupture lifetime of $($a$)1$ year? $($b$)15$ years? MPa