Land Rover Discovery: High Strength Steels

Most modern vehicles are constructed from a number of different steels, partly to obtain an optimized body, (collision, safety, rigidity, fuel economy, etc.).

Steels are divided into several groups according to their tensile and yield strength, that is to say the force necessary to bring about plastic deformation of the material.

Yield Summary

Yield is the strength at which the metal changes from elastic to plastic in behavior, the point of no return.

Tensile Summary

Tensile strength is the breaking strength of a material when subjected to a tensile (stretching) force, the point of no return.

Dual Phase (DP) steel falls into both the VHSS and EHSS classifications, dependent on grade of DP.

Welding Ultra High Strength Steel

Ultra high strength steel requires welding equipment which can achieve the following equipment settings.

Spot Welding

Information to follow.

MIG Brazing

When mig-brazing use the following type of welder meeting the specifications shown: Fronius Trans Plus Synergic 2700 4 R/Z/AL MIG Welder, with CuSi3 (DIN 1733) 1.0mm filler wire with setting parameters 4, which is 92 Amps, Wire feed 4.6 m/min. Shielding gas L1 = pure Argon (DIN 439).

NOTES:

• The addition of Boron, for the side panel reinforcement "ring frame", and DP600 to the rear of the front side member, gives the body greater strength in a front or side impact.
• Steel, (including Bake Hardened (BH) and High Strength Low Alloy (HSLA), these are used in seat belt anchorages, hinge reinforcements and various small brackets and mountings
• The size of the slots are to be 20mm x 8mm and 30mm apart. Slots should be installed in accordance with this spacing. Where this is not possible, due to the indents in the panel, the slot should be made in the location of the original spot weld.
• Mig brazing is carried out at a temperature of 650ºC to 950ºC. To avoid degradation of the ultra high strength steel material properties, the temperature must be below 950ºC.

Dress the surface of the weld cap (brazed slot) with 60/80 grit belt sanders.

ALUMINUM PANEL INFORMATION

The design of the modern motor vehicle attempts to overcome two conflicting needs:

• Fuel economy - lighter, aerodynamic and fuel sensitive technology
• High levels of comfort - this often equates to higher specifications and more accessories

Aluminum alloy is the ideal material to meet these demands; it provides a lighter vehicle body. Aluminum is different from traditional steel, with the correct knowledge and suitable tools it is easily repaired.

There are two aluminum alloys discussed in this manual, the attributes detailed in the following table should be considered when deciding to repair or replace:

PLASTICS AND COMPOSITE

Plastics: Used in the front fender and in front fender support bracket.

Composite: Used in tailgate.

Body Repairs - General Information - IntroductionAccident Damage and Diagnosis

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