RIPPED MY HOE BUCKET OPEN LIKE A BEER CAN TAB!!

[Tollster]

Don't think any items such as this,will have a weld failure due to splatter or a normal arc strike,also don't think on an item like this convexity or concavity[normal amount of either] will either.Codes allow both to a certain amount.

Most welding codes allow some undercut,[1/32],and again,don't think 1/32 or even 1/16 would cause this.

Now,lack of fusion,yes,lack of penatration,yes.

I will disagree since the weld appears to be intact and the crack started at the toe of the weld and not within the throat area, therefore I believe it was undercut that initiated the crack.

 

[AKwelder]

the failure looks to be in the weld heat affect zone, as mentioned before. it looks like the weld ripped out where it joins the metal. One thing that can do this is lack of preheat. A small defect at a point like this can grow, hope all goes well on the repair

 

[djcvjc]

I have also destroyed my backhoe bucket but it is not Kubotas fault it is from abuse my land has more rocks than dirt my tractor has been used to remove dozens of large rocks and tree stumps most of which were too large for my little tractor.

I noticed the the bucket had started to bend but did not see any cracks then I noticed it was distorted and cracks appeared it looks like metal fatigue that square tube is pretty thin the sides bent in so I opted for a new bucket and I am not using it so hard.

A couple of pictures show some of the rocks my tractor has moved.

Dave

 

[Tollster]

I have also destroyed my backhoe bucket but it is not Kubotas fault it is from abuse my land has more rocks than dirt my tractor has been used to remove dozens of large rocks and tree stumps most of which were too large for my little tractor.

I noticed the the bucket had started to bend but did not see any cracks then I noticed it was distorted and cracks appeared it looks like metal fatigue that square tube is pretty thin the sides bent in so I opted for a new bucket and I am not using it so hard.

A couple of pictures show some of the rocks my tractor has moved.

Dave

View attachment 130573View attachment 130572View attachment 130574View attachment 130575

Those would be enough to give any BX a workout. Some appear to be close to 1 ton or better. I had luck pushing larger stones onto a steel plate and skidding them out.
http://www.tractorbynet.com/forums/projects/102305-pennsylvania-stone-wall-project-4.html
I concur with your assessment, its Cyclic fatigue from repetitive use, this is identified as you mentioned from the bending you had observed prior to the failure, much like bending a piece of thin sheet back and forth many times until it breaks, also note it failed within the heat affected zone (HAZ) adjacent to the lower toe, which would be prone to this type of failure under extreme repetitive use. This is also the thinnest member of the two parts joined, and the weld shows no signs of failure. (paint tightley adhered and intact showing no flaking nor cracking).

 

[greenmule]

You can't say one way or other,cause you all can't see that picture any better than me,I still would bet money that u.c. did not cause the failure,but without a better picture,none of us can be sure EXACTLY what caused it,[other than using it]..

As far as preheating,you do not need to preheat this material above 50-60 degrees,bet its just plan old carbon steel a106 pipe or a36 plate,preheat will do really nothing assuming metal was dry and clean before they welded on it,buildings/bridges/pressure piping is fabricated every day without preheating,codes don't say you have to on lower class carbon steels above about 50 degrees.

So,ice did not cause crack,not preheating did not cause crack,splatter and arc strikes did not cause it,concave or convex fillit did not cause it!

Which leaves lack of fusion and or lack of penatration,[cause I don't believe u.c. caused it either..

 

[Tollster]

You can't say one way or other,cause you all can't see that picture any better than me,I still would bet money that u.c. did not cause the failure,but without a better picture,none of us can be sure EXACTLY what caused it,[other than using it]..

As far as preheating,you do not need to preheat this material above 50-60 degrees,bet its just plan old carbon steel a106 pipe or a36 plate,preheat will do really nothing assuming metal was dry and clean before they welded on it,buildings/bridges/pressure piping is fabricated every day without preheating,codes don't say you have to on lower class carbon steels above about 50 degrees.

So,ice did not cause crack,not preheating did not cause crack,splatter and arc strikes did not cause it,concave or convex fillit did not cause it!

Which leaves lack of fusion and or lack of penatration,[cause I don't believe u.c. caused it either..

Its OK, I was just giving my professional opinion on the failure based on what I see in the photos as I make a living doing just that for the past 22 years. Everyone is entitled to their own opinion.
You are correct on this part not requiring it due to its thickness. but I would refrain from putting everything into one class, as preheating is required on ALL material over 1.0" (typically 200 degrees, and 400 for chrome based) thick per AWS, ASME SEC III 71 and winter 72, SEC V, and SEC VIII. code requirements.

 

[greenmule]

Well toll man,you got to realise that you ain't the only one thats been doing that for years!

I been doing "THAT",for about 30 years.

And if you reread my post,I did not put every thing in one class ,said low carbon steel,and this ain't close to being over even 3/8ths inch probably ,is it??

Codes say many things,you don't use something out of a code book that does not apply to the situation you are dealing with,do you?
And your code list[concerning preheat] is not complete by a long shot,what about asme b31.1 how about b31.3,how about asme section I? api 1104?[etc,etc.]

Than theres the fact that you got different grades of chrome steel,1 1/4,2 1/4,9 chrome...all have different preheating requirements,so pulling up a little code thing is like a preacher quoting 1 verse,unless it applies to the jpb at hand,and we ain't talking chrome steel or 1 inch thick stuff on this hoe,are we???

 

[greenmule]

But,no matter the details of this weld failure,the root cause is easy.

You could say abuse,fatigue,poor weld,little tiny hoe on a little tiny tractor,design,10-12 dollar an hour welder,wire welding process,not enough q.c.,company doing the work,BUT,thats not the root cause,root cause is like everything today,money and owner of main company,[kubota in this case,could have been deere,or kioti or ford or chevy],companies trying to make something that can be sold in usa the only way they can,cut corners,and still make mucho dollars doing it.

Making a product that is the best you can make it is not something that is done any mores,not even at nasa,they make things to sell,and to make money/save money.

If it lasts 20 years or 20 days,is not something that really enters into it,its can they sell it and make money.

 

[Tollster]

Well toll man,you got to realise that you ain't the only one thats been doing that for years!

I been doing "THAT",for about 30 years.

Actually, I had no clue what you do as your profile is empty, please fill it out so that perhaps we may be able to work together in the future, besides someone here may have a specific question and wish to PM you based on your knowledge, its benificial to everyone here on the board to reflect ones background as much as you can.

I mostly deal with ASME codes, some AWS and no API. All my background and certs are to pressure vessels, and piping. My current certs are to CP-189, ASNT-TC1A & ANSI N45. Which include Level II's in Ultrasonic shear wave, Magnetic Particle, Dye Penetrant, Visual Weld, and bolting, Visual leak testing, and Visual pumps, valves, hangers and supports. Also have containment liners and concrete, QC weld and QC mechanical.
Are you aerospace, power generation, petro chem, or aviation?

 

[greenmule]

I've worked in every industry except aerospace.[maybe even areospace,cause was on one job years ago where we never knew where it was going,many rumors though.]