Why can uneven quenching warp a steel plate?

Uneven quenching causes a steel plate to warp because it creates localized differences in cooling rates across the material. When a steel plate is quenched, uniform cooling is essential to ensure that the transformation of its crystalline structure occurs consistently throughout the object.12

If the cooling process is not uniform, different sections of the plate contract at different rates. This disparity generates significant internal residual stresses within the metal. Because these stresses are not balanced across the entire surface of the plate, the material undergoes physical distortion, resulting in warping. To mitigate this, metallurgists carefully select quenching media—such as oil, water, or salt brine—and utilize specific agitation techniques to achieve the desired physical properties while minimizing these internal stresses and deformations. Specialized processes like martempering and austempering are also employed in demanding applications to further reduce the risk of distortion.2