Can/Should/How Would I Weld Grader Blade Arm? (Pics)

Shield Arc · Apr 16, 2016

aschwerin said:
what rod size would y'all recommend? (AC/DC stick welder)

1/8-inch 7018!

Jim Timber · Apr 16, 2016

6011's more forgiving to the rust you might not be able to get out with a grinder.

Billrog · Apr 16, 2016

6011 will spit all over grind the rust of real good and it will be easier for you with 7018 which is a good rod to have on hand. 6011 is a good rod for burning through rust and paint but more difficult for a beginner to get a decent looking weld.

Jim Timber · Apr 16, 2016

Bah... It's as easy to run as anything else and if you run it colder it freezes solid in a heartbeat for that out of position stuff.

Arc weld · Apr 18, 2016

Run a 6011 root followed by a 7018 cap and get the best of both worlds, best penetration and best strength. Grind ALL of the old weld off on all pieces.

Jim Timber · Apr 18, 2016

Given that the base is likely A36, I don't think you have a leg to stand on arguing 70Ksi rods are stronger in this application. Base will fail before a 60Ksi weld is even stretched a little.

Shield Arc · Apr 18, 2016

Jim years ago I did some fillet weld break tests, on mild steel flat bar. 6010 5P-plus broke with 10-blows from a 4-pound hammer. 7018 that never seen the inside of a rod oven broke with 18-blows. 7018 right out of the rod oven broke with 23-blows.

Jim Timber · Apr 18, 2016

Ductility of the 6010 is lower than 7018, so I'm not at all surprised by that hammer test outcome. Given the application the OP is asking about, I'd still choose the harder rod that's designed to handle impurities in the base over one which won't. I've welded just enough farm steel to make sure I have the exhaust fan on before striking an arc on it. It's not only usually soaked in oil, chemicals, and dung, but also some of the worst metal poured out of a vat. I'll take the rod that says "Oh boy, my favorite!" instead of one that might turn to swiss cheese under the flux. Adding to that, the ease of running it out of position is a plus. If the OP reinforces the joint so the weld's not directly in shear, then I don't think it'll matter what rod is used.

Just my $0.0135 (it's tax day, gotta give Uncle Sam his cut)

Arc weld · Apr 19, 2016

Jim Timber said:
Given that the base is likely A36, I don't think you have a leg to stand on arguing 70Ksi rods are stronger in this application. Base will fail before a 60Ksi weld is even stretched a little.

The base metal didn't fail, the weld did. Look at the picture. A deep penetrating 5/32" 6010/6011 ran fairly hot followed by a 7018 pass(s) on top would be the strongest way to repair the broken weld. If done right with no craters at the end, would be immensely stronger than the weld that failed. That's how I would repair it and then decide if it needed more reinforcement or gussets. I think having a full strength, full penetration weld wouldn't need any extra reinforcement. That blade looks very cheaply made. Look on the bottom of the pipe were it isn't even a continuous weld. It wouldn't take much to clean up the base metal to nice shiny steel. It's not covered with oil and isn't all pitted so I don't see where that is an issue at all.

CalG · Apr 19, 2016

Considering how little of the original weld was doing anything (per the photo) it wouldn't take much to make a joint ten times stronger with ANY welding filler. If the OP has a welder, he must have some filler rod kicking around. Just use what is on hand.

I would add a wrap of some kind myself, as I tend to be hard on pull behind equipment ;-) Even a 2 inch strap on each side would do.