GM Service Manual Online
For 1990-2009 cars only

This information provides repair recommendations and general guidelines for steel classified as Ultra High Strength Steel, also know as UHSS. This type of steel normally has a tensile strength greater than 700 MPa.

This includes the common steel names of

    â€¢ Ultra High Strength Steel (UHSS)
    â€¢ Martensitic Steel (MS)
    â€¢ Press Hardened Steel (PHS)
    â€¢ Boron Steel

General Motors recommends the following when repairing or replacing this type of steel during collision repair.

Important: 

   â€¢ Repair of this type of steel is not recommended.
   â€¢ This type of steel should be replaced only, at factory joints. Sectioning or partial replacement is not recommended.
   â€¢ The use of heat to repair damage is not recommended for this type of steel.
   â€¢ Stitch Welding is not recommended for this type of steel.
   â€¢ This type of steel can not be used as a backing reinforcement or a sleeve for a sectioning joint.

Recommended Repairs

    â€¢ Squeeze Resistance Spot Welding can be used to replace factory spot welds, where applicable.
    â€¢ MIG plug welding can be used to replace factory spot welds.
    â€¢ MIG Brazing can be used to replace factory spot welds.