Mechanics of Materials - Statically indeterminate axially loaded members thermal expansion example 1

[@oldwolfp]

Idk why but i cant get that delta L value. Got 0.607 x 10^-3 in. Similiar but dont know where the difference came from

[@cagolisano5551]

I got 4.89*10^-5 and ı've done the whole calculation for 3 times