Crater cracks are usually the result of:

Crater cracks in welds are primarily associated with the cooling and solidification processes of molten metal. They typically occur when the welding procedure is not executed properly, which relates closely to the specifics of welding techniques used.

When welds are not adequately controlled in terms of heat input, cooling rates, or technique, localized stress can develop at the end of a weld bead where the molten metal solidifies. This results in small cracks, often referred to as crater cracks. Addressing the welding technique is crucial, as it encompasses factors such as travel speed, electrode angle, and heat intensity—all of which significantly influence the final weld integrity.

While factors like the wrong base metal or improper filler metal can certainly lead to other issues in welding, crater cracks are most directly tied to the specific nuances of welding techniques. Hence, focusing on the welding technique is key to understanding and preventing crater cracks in welded joints.