A rod is rigidly clamped between two fixed walls and its temperature is raised by ΔT. The thermal stress developed (Y = Young modulus, α = expansion coefficient) is:

A typical stress-strain curve: the initial straight line (Hooke's Law region, slope = Young's modulus) ends at the elastic limit; beyond the yield point, deformation becomes permanent, peaking at the ultimate tensile strength before the wire finally fractures.