Light-weight, roll-bonded heavy duty truck frame member

1. A frame assembly for a vehicle, comprising:

two frame rails that extend parallel to one another, wherein each of the two frame rails are C-shaped in cross-section and each comprises a vertically-extending web, a horizontally-extending top flange extending from the web, and a horizontally-extending bottom flange extending from the web;

wherein each of the frame rails has a first outer steel layer, a second outer steel layer, and an aluminum core layer metallurgically roll-bonded between the first outer steel layer and the second outer steel layer to form a C-shape in cross-section;

wherein in cross-section, the first steel layer and the second steel layer are coextensive with the aluminum core layer over the frame rails with exception to a first portion and a second portion at ends of the C-shape that are not enclosed the first steel layer and the second steel layer;

a plurality of cross-members that extend transversely between and are fixedly attached to the two frame rails.

2. The frame assembly of claim 1 wherein the plurality of cross-members are formed with the first outer steel layer, the second outer steel layer, and the aluminum core layer.

3. The frame assembly of claim 1 wherein the first outer steel layer and the second outer steel layer are formed of one of high strength heat treatable steel, high strength low alloy, stainless steel, and metastable austenitic stainless steel alloys.

4. The frame assembly of claim 1 wherein the aluminum core layer is formed of one of high strength aluminum alloy and heat treatable aluminum alloy.

5. The frame assembly of claim 1 wherein the thickness of the aluminum core layer is at least twice as thick as the thickness of the first outer steel layer in cross-section.