What is one method to control expansion when welding a joint?

Tack welding is one effective method to control expansion when welding a joint. This technique involves applying small welds at strategic points along the joint to temporarily hold the pieces together while the full welding process is completed. By doing so, it helps to minimize distortion caused by heat expansion during the welding process.

As the welds are completed, the tack welds provide a guideline for alignment and reduce the risk of the parts shifting due to thermal expansion. This method is particularly useful because it allows the welder to manage and compensate for the expansion that occurs as the metal heats up, thereby helping to maintain the integrity and shape of the workpiece after the welding is finalized.

Other methods, such as cooling the workpiece beforehand, may seem practical but can introduce other issues like affecting the mechanical properties of the metal or leading to inadequate fusion. Using a thicker welding rod may increase the amount of metal being added but does not directly address the control of thermal expansion. Applying a lubricating agent does not relate to thermally-induced expansion and is not a technique utilized in welding practices.