Is this the proper way to weld a patch?

[flusher]

The truck upfitters use fish plates a lot when modifying a chassis (lengthening, shortening, offsetting). The ones I've seen usually are welded completely around the perimeter of the plate and have a few plug welds in the fish plate.

 

[Travelover]

sort of... Tension and compression stresses are at a maximum at top and bottom when bending but shear stress due to bending is maximum in the center of the section. Still need to size the 'web' appropriately.

This is true but for a beam of the relative dimensions the OP asked about shear is not the dominant likely failure mode. It would be for a short, thick beam.

 

[jwmorris]

If you want to weld all the way around your fishplate is correct if it were a square plate, you would have only wanted to weld parallel with the beam and plug welded inside the plate.

A vertical weld would only cause a "stress riser" and subsequent failure at that point.

One can weld too much and make a structure more prone of failure.

I have a book I give to new welders called Welding Secrets by Hal Wilson, that illustrates that point as well as others.

In short if you do it wrong you create a "notch" that focuses the stress into the material where it is most prone to fail.

Other than that looks like you didn't clean the weld area well enough leaving rust in the beam that would lead to inclusions in the weld and didn't allow the fillet to completely tie the plate to the beam. It also looks like you were too "cold" from 6 o'clock to 3 o'clock, better at the tip around 7 o'clock but that is the main problem with MIG welding, being that if you are not there watching as it is being laid down, it might look great but have little penetration. Why we have X-ray, dye penetrant, etc to test them after the fact.

 

[Shield Arc]

The secrete to getting good penetration with the Mig process, is very simple. Pure power!
224-amps, 29-volts.

 

[4570Man]

The secrete to getting good penetration with the Mig process, is very simple. Pure power! 224-amps, 29-volts.

What gauge wire do you run for that kind of juice?

 

[dragoneggs]

The secrete to getting good penetration with the Mig process, is very simple. Pure power!
224-amps, 29-volts.

Hard to argue that (except for your spelling)... and purdy weld too!

 

[dragoneggs]

Hard to argue that (except for your spelling)... and purdy weld too!

Or is 'secrete' a clever play on words? :laughing:

 

[jwmorris]

Amperage, wire speed, diameter of the wire, how clean the weld area is, shielding gas/flow and where it is all directed all have effects on penetration.

The second photo above (#14) is less than 50% into the parent material looking into the "pie".

 

[Shield Arc]

What gauge wire do you run for that kind of juice?

I think that was .035" wire. I ran that with my Lincoln V350-Pro inverter.

 

[LD1]

I have no idea how many amps I was running. My welder dont show that. Nor does it show wire speed.

My heat settings consist of heat range 1 thru 4. Then the finer settings called heat control which go low, then 1 thru 6, then high. Wire speed is just 1-10

Its a 225A welder. Running 035 wire. I was on heat range 4 and heat control 5. Only 2 settings hotter is max. So I would guess it to be in the ~200A range. And wire speed was 7.5-8 on the dial. These settings are spray welding. Using these same settings welding 1/4" stuff and I have to be careful not to burn through. Its penetrated in there well I can assure you. IT aint coming apart.