Read the Following Precautions When Repairing HSS:

• The repair of reinforcements (such as side members) by heating is not recommended since it may weaken the component. When heating is unavoidable, do not heat HSS parts above 550°C(1,022°F).

  Verify heating temperature with a thermometer.

  (Crayon-type and other similar type thermometer are appropriate.)

  Fig 1: Heating HSS Parts

  Courtesy of NISSAN MOTOR CO., U.S.A.
• When straightening body panels, use caution in pulling any HSS panel. Because HSS is very strong, pulling may cause deformation in adjacent portions of the body. In this case, increase the number of measuring points, and carefully pull the HSS panel.
  Fig 2: Straightening Body Panels

  Courtesy of NISSAN MOTOR CO., U.S.A.
• 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 (1.97in).
  Fig 3: Cutting HSS Panels

  Courtesy of NISSAN MOTOR CO., U.S.A.
• 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 M.I.G. welding. Do not use gas (torch) welding because it is inferior in welding strength.

  Fig 4: Welding HSS Panels

  Courtesy of NISSAN MOTOR CO., U.S.A.
• The spot weld 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.

  Fig 5: Identifying Spot Welding On HSS Panels

  Courtesy of NISSAN MOTOR CO., U.S.A.

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.
  Fig 6: Identifying Precautions In Spot Welding HSS

  Courtesy of NISSAN MOTOR CO., U.S.A.
• The panel surfaces must fit flush to each other, leaving no gaps.
  Fig 7: Precaution For Panel Surfaces

  Courtesy of NISSAN MOTOR CO., U.S.A.
• Follow the specifications for the proper welding pitch.
  THICKNESS SPECIFICATION
  
  

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

  Fig 8: Proper Welding Pitch Specifications Chart

  Courtesy of NISSAN MOTOR CO., U.S.A.