High Strength Steel (HSS) Used In NISSAN Vehicles

Fig 1: Precautions in Repairing High Strength Steel - Reference Chart

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

SP130 is the most commonly used HSS.

SP150 is used only on parts that require much more strength.

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 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 2: Repairing Reinforcements (Such As Side Members) By Heating Is Not Recommended

     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 3: Cautiously Pulling HSS To Avoid Deformation In Adjacent Portions Of Body

     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 4: Cutting HSS Panels Using A Saw To Avoid Weakening Surrounding Areas Due To Heat

     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 5: Welding HSS Panels Using Spot Welding In Order To Minimize Weakening Surrounding Areas Due To Heat

     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.

   • SP150 HSS panels with a tensile strength of 785 to 981 N/ mm² (80 to 100 kg/mm² , 114 to 142 klb/sq in), used as reinforcement in the door guard beams, is too strong to repair. When these HSS parts are damaged, the outer panels also sustain substantial damage; therefore, the assembly parts must be replaced.
     Fig 6: Cutting Spot Welds On A HSS Panel Using A Low Speed High Torque Drill (1,000 To 1,200 Rpm)

     Courtesy of NISSAN MOTOR CO., U.S.A.
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.
     Fig 7: Sizing Electrode Tip Diameter Properly According To Metal Thickness

     Courtesy of NISSAN MOTOR CO., U.S.A.
   • The panel surfaces must fit flush to each other, leaving no gaps.
     Fig 8: Fitting Panel Surfaces Flush To Each Other Leaving No Gaps

     Courtesy of NISSAN MOTOR CO., U.S.A.
   • Follow the specifications for the proper welding pitch.
     Fig 9: Specifications For Proper Welding Pitch (1 Of 2)

     Courtesy of NISSAN MOTOR CO., U.S.A.
     Fig 10: Specifications For Proper Welding Pitch (2 Of 2)

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