High strength steel is used for body panels in order to reduce vehicle weight. Accordingly, precautions in repairing automotive bodies made of high strength steel are described below:

Tensile strength | Major applicable parts
370 - 780 MPa |

- Front side member
- Hoodledge extension
- Hoodledge reinforcement
- Front cowl top assembly
- Upper dash
- Lower dash
- Lower dash crossmember assembly
- Front pillar brace
- Lock pillar reinforcement assembly
- Inner lock pillar assembly
- Outer sill reinforcement
- Inner sill
- Center front floor
- Front floor
  (Component part)
- Rear seat crossmember
- Other reinforcements

980 - 1350 MPa |

- Front floor
  (Component part)
- Inner side roof rail
  (Component part)

Read the following precautions when repairing HSS:

1.Additional points to consider

- The repair of reinforcements (such as side members) by heating is not recommended, because it may weaken the component. When heating is unavoidable, never heat HSS parts above 550°C (1,022°F).
  Verify heating temperature with a thermometer.(Crayon-type and other similar type thermometer are appropriate.)

- When straightening body panels, use caution in pulling any HSS panel. Because HSS is very strong, pulling may cause deformation in adjacent sections of the body. In this case, increase the number of measuring points, and carefully pull the HSS panel.

- When cutting HSS panels, avoid gas (torch) cutting if possible. Instead, use a saw to avoid weakening surrounding areas due to heat. If gas (torch) cutting is unavoidable, allow a minimum margin of 50 mm (1.97 in).

- When welding HSS panels, use spot welding whenever possible in order to minimize weakening surrounding areas due to heat.
  If spot welding is impossible, use MIG. welding. Do not use gas (torch) for welding because it is inferior in welding strength.

- Spot welding on HSS panels is harder than that of an ordinary steel panel.
  Therefore, when cutting spot welds on a HSS panel, use a low speed high torque drill (1,000 to 1,200 rpm) to increase drill bit durability and facilitate the operation.

2.Precautions in spot welding HSS
This work should be performed under standard working conditions. Always note the following when spot welding HSS:

- The electrode tip diameter must be sized properly according to the metal thickness.
- The panel surfaces must fit flush to each other, leaving no gaps.
- Follow the specifications for the proper welding pitch.

  Unit: mm (in)
  Thickness (T) | Minimum pitch (L)
  0.6 (0.024) 0.8 (0.031) 1.0 (0.039) 1.2 (0.047) 1.6 (0.063)
  1.8 (0.071)
  10 (0.39) or more
  12 (0.47) or more
  18 (0.71) or more
  20 (0.79) or more
  27 (1.06) or more
  31 (1.22) or more