Heat treatment of panels (Freelander 2)

It is usually inevitable that some parts of the body panels will show excess material as a result of mechanical deformation. If there are any areas of excess material, this will cause local buckling due to the differences in material tension. These local buckling areas can be stabilized by heat treatment.

NOTE: This does not apply to high strength mild steel, ultra high strength steel and aluminum panels.

Rule: Straightening panels by heat treatment reduces the amount of excess material to a greater extent than the initial stretching.

Various heat treatment methods

NOTE: Depending on the amount of excess material, different heat treatment methods are used.

Straightening using a torch.

• If the excess material is observed in a large area, a welding torch is used (torch size 0.5 - 1.0 mm). Use a weak flame.
• The metal surface is briefly heated in spots and then immediately cooled with a damp sponge.
• Requirement: Ability to properly handle a welding torch and knowledge of steel annealing colors.
• Advantage: No damage to the metal surface.

Correction using a hammer burner and a dummy stamp.

NOTE: Straightening efficiency is increased by accelerating heating and cooling.

If the excess material is concentrated, then the straightening efficiency can be increased by carefully using an aluminum or wooden hammer after heating.

Requirement: Ability to recognize the stress state of a material by observing the surface to be straightened.

Straightening using a carbon electrode.

• If areas of the panel are only accessible from one side or the panel is only slightly buckled, carbon straightening is the preferred straightening method.
• Requirement: Bare metal surface.
• Disadvantage: Presence of scratches and hardening of the surface.

Straightening using a copper electrode.



Small, sharp dents that face outward can be removed using a copper electrode.

Correction using a torch and body files.

NOTE: When used correctly, this method can be used without removing all attached components (headliner, wiring harnesses, etc.).

Small dents (with only slight stretching): When processing the edges of the dent in a spiral inward direction, the dent is heated with an oxyacetylene torch (torch size 1 - 2 mm, excess gas flame) to a temperature of approximately 250°C.

Quick work with a body file removes heat from the boundary zone and so on until the dent is straightened out. It is preferable to alternate work with two files. This increases the amount of heat that can be removed.