How do I weld a crack on backhoe boom?

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Hi, I'm new here and thought this would be the best place to find my answers.  I have a Case 580 Backhoe.  There is a crack along the factory weld at the boom pivot casting.  I can see that the other side has been welded and built up before and has held.I read on a Case  forum that the casting is cast steel. not Iron.  Is this true?My plan on fixing this is to groove out the cracked weld with a burl (How deep?) and then use a welder (Mig?)  or (Stick?) to build it back up and add to the size of the original weld, like was done on the other side.  The casting is about 3/8 thick, and the boom is 1/4 steel. I'm not an expert welder but will practice until I think I can do thisIs my Plan Valid?What Welder?What welding material?Better way of doing it?It's all yours....and thanks in advance.
Reply:Save it for a pro that can weld it for you.  But if you are going to do it i would use 7018 stick rod .
Reply:As a rule of thumb on something like this where there will be a lot of stress to the weldment if you have to ask how, you shouldn't be making the repair. Don't take that the wrong way it's just that no one here wants to see you or anyone else get hurt by a faulty repair. As for repairing it you first need to gouge out the crack all the way to the bottom of it and for the eintire length of the crack. Then "V" it out ( make it into a v-groove) then proceed to fill in the crack but preheating the weld area before welding it would likely be preferred. As stated above I would use 7018 for the electrode choice but make sure the affected area is clean of any debris or foreign material first then chip and wire wheel after each pass.1973 Lincoln SA 200, Already replaced shunt coils, Idle board (SOLD)1984 Miller Dialarc 250HF, Miller water cooler, 250 AMP water cooled torch, you know the worx.
Reply:I would post a picture. Even though you explained it, some may not reply because of misunderstand and do not want to  give false info.
Reply:Before applying any heat, first thing I'd do is drill a hole at each end of the crack.Don’t pay any attention to meI’m just a hobbyist!CarlDynasty 300V350-Pro w/pulseSG Spool gun1937 IdealArc-300PowerArc 200ST3 SA-200sVantage 400
Reply:oh boyBacked my CATMA over your CARMA oops clusmy me  What would SATAN do ?? Miller Trailblazer 302 AirPakMiller Digital Elite  Optrel Welding HatArcair K4000Suitcase 12RC / 12 VSHypertherm PM-45Rage 3 sawRusty old Truck
Reply:Thanks cep I forgot to mention that.1973 Lincoln SA 200, Already replaced shunt coils, Idle board (SOLD)1984 Miller Dialarc 250HF, Miller water cooler, 250 AMP water cooled torch, you know the worx.
Reply:Originally Posted by killdozerd11oh boy
Reply:Many newer pieces of equipment are using high strength alloys. While they can be welded, the procedure varies depending on the alloy used and if they heat treated or tempered the unit to gain the strength. This can be especially true if you then go and need to weld this material to a cast piece.Preheat / post heat, using the right alloy filler and keeping the weld heat within tolerances will probably determine if this is successful or not.Older pieces of equipment aren't a fussy about procedures, but newer ones can be. Put too much heat into a high strength alloy or cast piece and chances are it will be unrepairable as you'll destroy the base material. Don't put enough in, and it will crack again.What sucks is getting the information on doing this right really needs to come direct from CASE. Most dealers however aren't very forthcoming about repair procedures. They'd rather either do the work themselves and charge an arm and a leg, or sell you a new part or better yet a new machines and rape you that way.Good luck..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:What he said ^. Case (Burlington, IA. hoes) started in the late 80's using boron enriched steels that behaved much like USS-X1050 with way better fatigue properties but using lower carbon (a lot of  off road SAE folks went this way). Anyway this is the major player in any of the new HSLA steels. They do not like slow quenches and such required from older traditional constructional alloys. And if welded require a better filler match than the old stuff and much tighter heat inputs ( I hate the S#iT, they are less robust, and take the art out of the build).The upside was they were (and are) more predictable in manufacture, the downside is when they are used up (fatigued) they cannot gain anything near the properties of the original product (thanks Caterpillar for figuring it out) either from welding or in fact, if not broken then even from heat treat (wonderful)....I think a search (here) may reveal someone who puked his guts as to how many hours in sandy soil etc, the dipper & such may be expected to work.Good LuckMatt
Reply:Case 580 likely and older machine, got a birthday on her?"Si Vis Pacem Para Bellum"Lincoln Idealarc 250 AC/DCMillermatic 251   Syncrowave 300   30A spoolgunLincoln MP210Hypertherm 45(2) LN 25(2) Lincoln Weldanpower 225 CV(4) SA200   1 short hood    SA250    SAM 400
Reply:Hi Again, and thanks for all the wisdom so far.  I like what I'm seeing.I will post a detailed picture tomorrow, that was an excellent idea.Also the age of the machine is 1971.  I restored this machine to like-new condition about 10 years ago and it still looks that way.  I don't know who welded the mirror side or when.  But like I said, that (amateur looking) job held.The reason  why I don't have the local "Pro" weld it, is because he showed up with a Harbor Freight flux wire  welder that was capable of  90 amps in the trunk of his car.   He unrolled his 16 gauge 120 foot extension cord and asked me where to plug it in.   I said I changed my mind.  Two other "Pro's"  can't do it until August or Later.  I want to do it myself.  For Mig I have a Hobart  Ironman 230 MIG Welder   Argon/CO2 Tank and Straight Argon tankFor Stick I have a Lincoln AC-225 welder.I also have Oxy/Acelylene for the pre-heating that was discussed.IF THIS IS ANY HELP----A few years back A crack started on one of the loader arm factory joints. This too was between a cast  piece and 1/8 rolled steel.   I grooved the old weld out with a burl to about 1/4 inch wide and then drilled an 1/8 hole at each end of the crack.I built it back up with the 7018 rod that was mentioned, and it has never given trouble. I did not pre-heat anything.   I would think the metallurgy of the machine would carry the same traits through-out?
Reply:Whats wrong with the 90 amp harbor freight, hes a pro from craigslist im sure.....And how dare you make fun of that 16 gauge cord, he paid more money for that than he did his welder...... Where the hell do u even get 120 foot cords at? I want one.I forgot how to change this.
Reply:Originally Posted by dswthe information on doing this right really needs to come direct from case.
Reply:Get ahold of Tozzi..He does this stuff all the time and is MOBILE....zap!I am not completely insane..Some parts are missing Professional Driver on a closed course....Do not attempt.Just because I'm a  dumbass don't mean that you can be too.So DON'T try any of this **** l do at home.