Distortion on welded components is a common problem for welders. This occurs after the welding process, when the metals shrink as they cool. The welded metal cools faster than the thicker base metal. The metal stretches at the point of attachment to accommodate the difference. Welders can practice techniques that ensure smooth results during the welding process and eliminate the need to fix problems later.
Weld with as little weld metal as possible. A thick layer of weld metal on the component increases shrinkage in the work. The authors of “Industrial Machinery Repair” recommend relying on the penetrating force of the torch's electric arc to fuse the metals instead of adding more weld metal.
Minimize the welding time and weld intermittently with fewer passes. Welding a work point for long periods creates a higher heat input. This causes a longer cooling time, which leads to a higher level of distortion in the metals.
Place welds near a neutral axis. The level of shrinkage and distortion lessens when the weld is close to a point that is not subject to stress or strain.
Match the components you plan to weld to ensure a good fit. Components snug when fit together have limited shrinkage as the metals cool and gaps close.
Weld components together with thermal welding methods. Heat sink welding and thermal welding reduce distortion during the welding process, according to Zhili Fang in “Processes and Mechanisms of Welding Residual Stress and Distortion.” Heat sink welding uses a cooling source to draw heat from the welding point. Thermal welding using a heating source to redirect heat from the weld point.
Tips & Warnings
- Plan the order in which you will weld the components together. Planning the welding sequence can help you avoid potential problems, eliminate unnecessary movements and complete the work faster. An organized work sequence also minimizes the amount of heat applied to the weldment. Welded components shrink less with a lower level of heat.
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