Why is alloy steel that responds to heat treatment generally less suitable for welding?

Alloy steel that responds to heat treatment may contain certain elements that enhance its strength and hardness when properly heat-treated, but these same attributes can lead to challenges during welding. When welding such materials, the localized heat from the welding process can alter the microstructure of the alloy steel in the heat-affected zone. This can result in increased brittleness and a loss of ductility, which are critical properties for materials expected to perform under stress or impact.

The weld zone and the adjacent areas that were affected by the heat of the welding process can transform into a structure that is prone to cracks and failures. This is particularly relevant because brittle materials are less capable of absorbing energy without fracturing, which can lead to catastrophic results in applications where the welded joint must endure dynamic loads or severe conditions. Therefore, the potential for embrittlement and loss of ductility at the weld makes alloy steel that responds to heat treatment generally less suitable for welding.