Welding Across the Chord of a Beam

I am not a welder or a mechanical engineer so any possible solutions I offer will be nothing more than a novice's speculations. I do think that this is a situation that a few pictures will be worth a million words. Can you take a couple of digital pictures and post them here so that the mechanical engineers here can get a better look at your situation.

Hi redfred,

Don't cut yourself short. You have quite a few #1's your self.

Your honesty is honorable.

You say "...right at the point of the cast steel hinge joint connection...". Is this the joint in the middle of the stinger, or at the bucket? Is it a bolt on hinge, or pinned joint?

redfred is right...

Manufacturer and model may help as well.

I sort of suspect the stinger has been rotationally torqued, and the boom holds some memory of that in a pinned joint somewhere. If bolted hinges, it will be should be simple to confirm or reject this as cause.

I wonder what jerk voted this as OT.

435853 you have been hitting to much vino my son.

In preparing it did you drill out the ends of the crack. You need to find the ends of the crack and drill a holes though to terminate the end. Not sure what your definition of gouging is. I would grind in to the crack until I was sure I could get thru penetration with the first pass then back fill the groove I ground. Also if possible I would fish plate over the crack.

After the repair is made I would check my hydraulic relief pressure. It may have drifted or has been changed over stressing the boom.

As with the previous post, I wonder what jerk voted this as OT.

As you know machines in the field don't have time to go to a shop for oven use.

fix it now.

Who is the lawyer?

I would need to know how thick material is. Does the crack go all the way through the steel.

Say the steel is 1/2"thick, and thecrack wentall the way through.

I dont think it is the heat,I would heat it just enough until the moisture came to top of steel, evaporated. Idon,t know how wide you gouged,I am assuming air carbon arc,Make sure all slag is out of weld joint. I would have welded with the 1/8 7018 dcrp rod all the way out. don't grind right away stress relieve it by peening with ballpeen hammer for a short time and flame cool it. Do not let any breeze blow on it. when it cools to ambient temperature inspect for cracks,if none appear dont grind if you dont have to. Weld should be no more than 1/16 above base metal.( A little grindin a little paint makes a welder what he aint.) I'm sure that will help if no oil or grease inside.

Apart from what others have suggested, I feel it could be a fatigue failure with increased no. of stress cycles, excessive load on the job or stress fluctuations. It happens in most of the heavy equipments used in the field. Further the material is a cast steel and stress factor will be on a higher side.

But you have not mentioned of the arm thickness. I assume it, to be more than 20 mm. Procedure is more important in in any repair welding.

The repair procedure requires a preheating temperature of min. 350⁰C and use of a high strength alloy electrode and with a good ductility. Use of E 7018/ E7016 will not solve the problem and should be avoided as the weld metal will not with stand the stress concentration on heavy thick cast steels and cracks up immediately. The post weld may also require stress relieving which is not practical in those areas.

On the other hand you can substitute it with crack resistance friendly electrodes like E 18Cr-8Ni-5Mn (E18.8-Mn B45) or 30Cr-10Ni (E312) type electrodes or even 25Cr-20 Ni (E310) for your any type repair jobs.

These electrodes give a higher weld metal tensile strength and has a ductility more than 35-40 % and lasts longer than a joint done with E 7018.

They also work wonders and produce crack free joints in any type cast steel, difficult to weld steels, any high alloy steels or even unknown steel material compositions.

On safer side you have to pre-heat the joint to be welded to min. 200⁰C to burn off any oil, grease stains or hydro carbons accumulated on the surface or underneath of the material.

Welding could be continued there onwards using a DC rectifier with a positive (+ve) polarity for the electrode. Use 4.00 size electrode with a heavy current (10% more) for the first pass and moderate currents for the balance runs. But make sure that the electrode coating should not be over heated.Check for any defects in the first pass and continue further and finish the repair weld.

No post stress relieving is required in general and I am sure the weld will withstand more stresses than the base metal.

Sridhar.

To many if's and's or but's. It could be this it could be that,if the material is fatigued it should be replaced and not welded. Lets get right to the point,Lets not assume anything.

If you want to use 7018,7016.Use them, you have to many procedures.You have Stainless family, mild steel, all over the place.

I myself would bevel crack down to a feather edge clean slag ,grinding dust, which ever you prefer.

Heat about 200 degrees fahrenheit, we dont know whats inside. Tig weld at 60amp D.C.S.P 98% Argon 1/8 Inconel wire. write or wrong to the point!

As I stated before If the material "could" be fatigue faliure it should be replaced. once a piece is fatigued which does happen in all heavy equiptment Machinery. from fatigue the material gets soft, grain structure begins to loose Its properties,by this I mean It is not the material it used to be.Inside the tube is always oil grease, I know I have done plenty of these.

As far as stress cycles,and excessive load,and stress fluctuations should tell you that the metal is stretched beyond it's limits. As far as the material being cast steel,cast steel welds better than cast Iron. You would have to do a small test to prove if it is cast iron or cast steel.All it takes is a grinder.I replaced a plate on the tube welded some gussets inside to the piece through a hole I cut in the side,plenty of grease inside,Had to clean that.then back to welding with a 1st pass 5p+ Then 5p+ Hot pass, Then all the way out with a 7018. 7018

Does work well on cast steel we in the pipefitters use 5p+ and 7018 on gas lines and high pressure steam. 435853.

Thanks y'all. I knew how I should have done it. You know human nature. When you haven't done it in quite while and you are pushing to get it done quickly. You question the nescessity of the extreme measures. I have temp sticks for aluminum but I knew they were wrong, but couldn't remember the right temp.

Thanks again.

I hope that in time, I may contibute at least twice that which I have taken.

Try here Liberty...

http://www.heavyequipmentforums.com/Forum/

Lots of what your looking for.

Skies.

Jay.

I have been so busy fixing and patching along with trying to finish jobs and going away every other week to get smarter than I need to be, I haven't finished the job as yet. The crack is on the upper end of the boom that connects to the dipper stick. The crack is from one side to the other on the top side(cylinder side) right at the end of the fabricated portion connects to the cast steel end portion where the hinge pin couples to the dipper stick. The bucket is on the opposite end of the dipper stick. The crack is fully in the steel sheet that forms the boom. So we aren't welding in the cast portion. There is a formed (concave) rib that is in the center of the top (axially), which the crack crosses. The thickness is about 3/16"-1/4". I have some nickel rods that has been recommended that I use like a 7018. I wish I could post a picture. My camera disappeared about the same time I picked up a young couple walking in the rain. My brain(bag I carry files and stuff in) was behind my seat and open when I got home. No good deed goes unpunished, I guess. The boom is on a Ford/New Holland 575-E tractor loader bakhoe.

I have been so busy fixing and patching along with trying to finish jobs and going away every other week to get smarter than I need to be, I haven't finished the job as yet. The crack is on the upper end of the boom that connects to the dipper stick. The crack is from one side to the other on the top side(cylinder side) right at the end of the fabricated portion connects to the cast steel end portion where the hinge pin couples to the dipper stick. The bucket is on the opposite end of the dipper stick. The crack is fully in the steel sheet that forms the boom. So we aren't welding in the cast portion. There is a formed (concave) rib that is in the center of the top (axially), which the crack crosses. The thickness is about 3/16"-1/4". I have some nickel rods that has been recommended that I use like a 7018. I wish I could post a picture. My camera disappeared about the same time I picked up a young couple walking in the rain. My brain(bag I carry files and stuff in) was behind my seat and open when I got home. No good deed goes unpunished, I guess. The boom is on a Ford/New Holland 575-E tractor loader bakhoe.