What is the most likely cause of centerline solidification cracking during welding?

Centerline solidification cracking is a common issue encountered during welding processes, particularly in certain alloy types. The most likely cause of this type of cracking is related to the speed and thermal conditions of the welding operation.

When welding at too high a speed, the heat input is insufficient to create the necessary temperature gradient conducive for proper solidification. This rapid cooling can prevent the liquid metal from having enough time to properly settle and fill the joint, leading to internal stresses as the metal solidifies. Consequently, this condition increases the likelihood of forming cracks along the centerline as the weld pool solidifies too quickly without adequate distribution and fusion of the molten material.

In contrast, slower welding speeds typically allow for greater heat input, which facilitates more uniform solidification and reduces the likelihood of stress concentrations that can lead to cracking. While low heat input and high temperatures can also impact weld quality, they do not directly correlate with centerline solidification cracking in the same way that excessive welding speed does. Therefore, the most significant factor contributing to centerline solidification cracking is indeed welding at too high a speed.