welding to hard surfaced material.

Date 05-08-2009 19:15

im sure you know the answer but don't like it, gouge not only the hard-surfacing off but also down into the diluted (parent metal/hard surfacing) area.
also keeping the wire volts to 28.5 or less will help stop the carbides from forming, way slower but helps stop cracking.
at least your doing this now instead of in the summer when its 40 degrees.
i looked up the t91 and it said that it is equivalent to 7018 fro low hyd and tensile strength.
unless it is a demanded wire because of the wps or cost constraints, i would look into a wire that has 1 to 2 % nickle
it gives it way more flexibility, when we went to it on buckets it made everything less prone to cracking. arctec makes a good wire for this but i am sure many companies do.
im sure you knew all of this as your experience is greater than mine on these issues, but i just wanted to make sure my self that i hadnt forgot how to solve welding concerns.
darren

http://www.arctecalloys.com/app/prodlist.asp?action=3&ptID=5

By makeithot (***)

Date 05-10-2009 22:55

I am also a big fan of artec rods and wire . Sadley they are not readly available on the sunshine coast. I am going to try that lower voltage suggestion I would normally run in the spray transfer mod 32-36 volts.

By Wrench Tech (**)

Date 05-09-2009 13:12

I've been using t450 for the liners in the buckets around here - usually 1/2 inch thick. I'm assuming excavator buckets but I know you are working with front end loaders there too. Also use E71-t9 .045 wire (or 1/16th) with preheat - straight CO2 though. But there is no hard surfacing. I never liked hard surfacing on any bucket. It does very little to add to bucket life, increases the chances of cracking where ever the bucket has to flex ( and they all do flex) and makes it really hard to work on it the next time. It's an old way to do things and best left in the past. But you gotta deal with it and all you can do (like you didn't know!) is air arc it outta there and hope that does the trick. I think the damage is done though. Boy, when I think of some of the ways I've seen hard surfacing used!!! You should tell that company welder in the the shop there to quit that and find some other way to make himself look busy on those rainy winter days. I kinda like bucket work - done lots of it - and made great money doin' it. Sounds like those guys are taking good care of you.(assuming Cewe) BTW...how's the thumb?

By Superflux (****)

Date 05-09-2009 16:07

When I worked in the coal mine, relining buckets from the gardener's little john deere to 134 cu. yd drag lines was a daily event. I agree with E71T as a choice of wire (this is what we/they used when I was QC for ESCO), although when I was in maintenance, we used Innnershield NR 211 for some real savings and ease of application.

I am however a Big fan of Properly applied hardfacing.

To make installation easier even though I'm sure you LOVE to gouge and grind...cut the new liner a 1/2" or so smaller than the existing one. This allows you to weld to some new and undiluted base metal without having to dig down into the parent shell for clean up. Use flat carbons to get the old hardfacing close, quick once over with the grinder to facilitate dross removal, weld on new liner.

Hardface sparingly and transverse to the direction of flow. Study the erosion patterns of the existing liner B4 you start and just use the hardface (Lincore 55) to make small "dams" where nesessary. This stuff is guaranteed to crack if welded in long continuous beads.

By Wrench Tech (**)

Date 05-10-2009 13:43

Well, okay. I knew when I posted that that not everyone would agree and I have to admit in some cases a little judiciuos use of hard surfacing might be in order. I`m taking care of a bunch of excavators and I know Richard is also (and more than a few front end loaders too). Where I`m working there is just no need to hard surface anything. I find it way easier to just arc out the old liner, get a new one formed, wedge it down and weld it in there with preheat. I just find cleaning up hard surfacing to be such a hateful job and it never seems to be put on properly.

Used lots of 211, too. Better in wind, smokey and slow, quicker than sticks.

By makeithot (***)

Date 05-10-2009 22:47

Then I think we're all the same page getting rid of the old hard surface is going to be the the key. I also hate hard surfaceing as it always makes bucket repiar such a drag and on a normal day would rather install wear plates.The thumb is on the mend but still not 100% started going to re-hap last week so that should speed things along a little.