What is a common method for controlling expansion when welding a joint?

Placing tack welds along the joint is a widely adopted technique for controlling expansion during the welding process. Tack welding involves applying small welds at intervals along the joint before the final welding is performed. This method helps to hold the materials in place and allows for the gradual distribution of heat, which mitigates the stresses associated with thermal expansion. By doing this, tack welds can effectively prevent warping or distortion of the workpieces as they heat up and cool down during the welding process.

Using a hammer on the weld, while it may help to correct slight misalignments after the fact, does not directly control the expansion during welding. Welding in cool environments can potentially make the base materials more brittle and may not always be practical or able to adequately address the thermal expansion issues. Utilizing thicker weld beads could result in increased heat input, potentially aggravating the problem of expansion rather than controlling it. Thus, tack welding stands out as the preferred method for managing this aspect during the welding operation.