Read this, deuce frames are not spring steel and not heat treated, they are OK to weld on.
TB-9-2300-247-40 Tactical Wheeled Vehicles: Repair of Frames Manual
Interesting read.
It says it is not ok to weld anything that should be riveted to the frame, and that it is not ok to weld on the flanges, corners, or extreme ends of the frame.
(The flange on an automotive frame is that which is not vertical.)
So, let's see how our score card goes thus far: The fillet weld is both on the flange, on a corner, and on the extreme end of the trailer frame.
The manual goes on to talk about the reinforcements necessary to protect the welded area... there are none on this application. I think there should be.
It requires that any welds be done with low hydrogen 7018 rods, using proper technique. This speaks to the hydrogen embrittlement that I discussed early in the thread. They also speak of minimizing the heating of the frame.
Otherwise, it talks about the same talk that is always done for frame repairs.
The whole issue is frames are live structural members. They flex and bend as the truck travels over hill and over dale. They need to be free of stress risers that can cause cracks to form. Welds that are made near edges, or on flanges are virtually impossible to make without creating stress risers, and will usually cause a crack to form... flanges and corners are a high motion area when frames flex.
Frames aren't generally tempered spring steel, or heat treated... and the deuce frame is probably neither. But it is a high tensile strength structural steel alloy, that is work hardened by the act of rolling the sheet steel and bending it into the shape of the frame. This work hardening is incorporated into the strength calculations when the frame is designed. Heating the steel changes the work hardening, and depending on the circumstances can make the heated portion of the frame be anywhere from dead soft to glass brittle.
As the cooks say, the proof of the pudding is in the eating. The way this, and any other, welded frame is used will go a long ways towards deciding whether it is a success or a failure. If the truck becomes a show queen, or a lawn ornament, it may well last forever. If it becomes a rock climber, or a heavy hauler it might stress the joints in ways they cannot handle... A whole lot of testing and research went into what has become the rules of engagement for frames and frame repairs. A lot of frames were broken before the first deuce was deployed.
-Chuck