Stress Calculation: The Landau Test Steel Plate - tempered from 1900º F to room temperature Here we see stress after 300 seconds. The plate first cools at the border and tries to contract there. As this contraction is hindered by the hotter material in the center, there is tensile stress at the border and a compressive stress at the center. The red colour indicates the tensile stress and the green colour indicates compressive stress. After 40 minutes, as the cooling spreads to the interior, the tensile stress is moved to the center, as now this region tries to contract. This produces the compressive stress in the center as well as the inversion in the now cooler border region. After 120 minutes, the shrinking of the center area is hindered by the plastical distortion of the border, as cooling moves on to the center. Shown here is the stress distribution after the complete temperature equalization. It is a reverse of the first picture. The compressive stress is now at the border and the tensile stress is in the interior. This is the result of the thermal or residual stress. Comparison between measured and calculated stress. Location means X-distance from the center point.