For simple bends in gate frames, an easy fix with an angle iron, sledgehammer, and torch can be used. An angle iron is either one or two pieces of metal bent or fused together at a right angle. This piece of equipment is helpful in spreading the hammer force across the bent sections. If the gate is bent in several sections, or the gate is bent inward or otherwise mangled, it may be best to replace the gate.
Lift the gate upwards and off its hinges. Lean the gate on the nearest fencepost with the bent section facing up. The gate should be in an upright position. Heat the bent section with the torch--acetylene works well on thicker or heavy-duty metals, while propane can be used with lighter metals, such as aluminium. The heat softens the bent section so it will be more malleable when hammering it back into place.
Place the angle bar on the bent section of the gate. Hammer with the sledgehammer on the angle bar. This angle bar will disperse the force of the sledgehammer and help the user determine when the bent section is aligned with the straight frame.
Remove the angle bar and set it aside along with the sledgehammer. Pick up the now straightened gate and place it back onto its hinges.
If it is better to have the gate lying down when fixing the bent, place pieces of wood underneath the four corners of the gate to hold up the gate a little from the ground.