A curve $y=f\left(x\right)$ satisfies $\frac{d^{2}y}{d{x}^2}= 6x- 4$ and $f\left(x\right)$ has local minimum value $5$ at $x=1$. If $a$ and $b$ be the global maximum and global minimum values of $f\left(x\right)$ in interval $[0,2]$, then $ab$ is equal to