I forgot more than I ever knew about

[gotrocks]

Tempering metal.
I was just moving along (on B-2910 Kub) in Hi slower than I usually walk the tip of my middle buster hung the edge of a concrete post I had laying horizontal to stop wash.
Whang, the middle buster busted.
Please tell me what you think about the looks of the break. I have always thought the "crystalized" appearance of this break indicated a brittle temper.

What say you? Will just welding it back hold for normal use?

Thanks to all who reply.

Norris

 

[Shmudda]

Personally it looks like a normal overstress or fatigue type fracture to me. I would prep it good with some chamfers and weld the heck out of it getting a good full pentration weld. You should be all set to go again. It won't break at the weld again, next time it will break at the heat effected area of the weld which is directly beside the edge of the fillet.

Craig

 

[GinNB]

Weld a gusset perpendicular to the crack after you've filled in the chamfered edge with weld.

 

[3RRL]

Yeah, just weld it back after proper weld prep and deep chamfers.
I'd consider 6011 for root pass and 7018 to finish. Preheat for good measure and blend back to original shape. Let it cool down on it's own. A reinforcing gusset or two sure wouldn't hurt if it doesn't interfere with the blade.
Looks to me from the rust (unless it was sitting around before you took the photo) that a crack had been formed for a while and you just popped it the rest of the way this last time. That middle buster has probably seen it's share of work in the past.

 

[IH3444]

You are correct in that the metal was very brittle there at the heat affected weld zone. If you do weld it, you might want to pass a Rosebud torch head, or a single tip torch across it to annel the weld site slightly. The metal strap looks to bit thin, that possibly could be beefed up, or double layered.

 

[gotrocks]

Thank to all who have posted. I'll try to follow your directions as best I can.

Re: Looks to me from the rust (unless it was sitting around before you took the photo) that a crack had been formed for a while and you just popped it the rest of the way this last time. That middle buster has probably seen it's share of work in the past.

Actually, it has not seen a lot of hard use. When it broke the entire visible broken surface was "clean" no rust at all. Yep, I let it sit a while before picture taken.

Thanks again.

"Strike while the iron is hot!" Is that what happened to US Steel?

 

[CharlieTR]

Yeah, just weld it back after proper weld prep and deep chamfers.
I'd consider 6011 for root pass and 7018 to finish. Preheat for good measure and blend back to original shape. Let it cool down on it's own. A reinforcing gusset or two sure wouldn't hurt if it doesn't interfere with the blade.
Looks to me from the rust (unless it was sitting around before you took the photo) that a crack had been formed for a while and you just popped it the rest of the way this last time. That middle buster has probably seen it's share of work in the past.

I guess I am not sure when thing should cool on their own or be quenched with water. I thought everything should be quenched except for cast items, bent or welded. Is this not true?

Thanks,
Chuck

 

[Kyle_in_Tex]

Make it too strong and your 3Pt will break instead...

Depending on the metal, water can quench and harden but also make it brittle. For something like this you just want it to cool slowly like 3RRL said.

 

[3RRL]

I guess I am not sure when thing should cool on their own or be quenched with water. I thought everything should be quenched except for cast items, bent or welded. Is this not true?

Thanks,
Chuck

Hi Chuck,
Without getting my Machinery's Handbook out, the best thing you could do after welding and letting it cool slowly is to re-heat it slightly to (my guess) about 800F (if I remember correctly) depending on material and let it cool from there. That temperature is way less than the welding temperature. This is called tempering. That let's the steel regain some ductility while retaining strength. You would use a rosebud torch if you don't have a heat treat furnace. You can heat it with a torch to just before it starts to show color...before it glows any. It is especially important to do this (temper it) if quenched in water or oil to reduce the glass hardness and brittleness.
If you don't have a torch handy, always let the weld cool slowly by itself. I usually leave the slag on and chip off after cooled down as the slag helps retain the heat a little longer than when removed right away...my two cents.

 

[AlanB]

I guess I am not sure when thing should cool on their own or be quenched with water. I thought everything should be quenched except for cast items, bent or welded. Is this not true?

Thanks,
Chuck

Generally, cooling things slower results in more ductility / flexibility / malleability and less hardness. It also tend to minimize cracking etc. caused by rapid shrinking.

Generally, cooling things by quenching in your favorite mix of coolant, whether water, oil, salt water, etc. etc. will make things harder, more brittle, "tougher wearing" (that can be an interesting discussion on itself.

The trick is usually to get the stuff hard enough to stand up too what it has too do, yet soft enough to have some give so it does not snap off.

When I have cast parts especially or other things I want to cool even more slowly, I keep a sandbox that I bury the thing in immediately after welding to slow the cooling process even more.