What is a key advantage of proper preheating before welding?

Proper preheating before welding plays a crucial role in minimizing thermal distortion, which is one of the significant advantages of this practice. When metal is welded, the heat input during the welding process causes localized expansion. As the metal cools down, it can contract unevenly, leading to residual stresses and distortion. By preheating the base metal, the temperature gradient across the weld zone is reduced, leading to a more uniform cooling rate. This uniform cooling helps to stabilize the structure and significantly lowers the risk of warping or other forms of thermal distortion, ultimately resulting in a more precise and accurate final product.

Other factors, such as electrical conductivity, welding speeds, and the necessity for post-weld treatments, do not directly correlate with the primary benefits of preheating in addressing thermal stresses and distortion. Thus, preheating is fundamentally about managing heat and ensuring the integrity of the material during and after the welding process.