Cooling welded connection

[Cami]

Bucket thread? For a portion of my apprenticeship I was the "bucket *****" for a heavy equipment repair company. The stress put on buckets, along with the simplicity of their design made the work on them critical but mind-numbing.

For tooth shanks, we always used a 400 degree preheat and either low hydrogen rods or a dual shield wire; no concerns about interpass temperatures or post heat. On the subject of tooth shanks, if you're going to hardsurface between the shanks, keep at least 3/8" away from the shank welds as the stress induced by the hard surface material shrinking can start a crack on them.

@killdozerd11: Backed your catma over your carma, eh? By the time you feel anything, it's too late.... I know a guy who trimmed the front 18" off the front of a service truck with a log loader; he didn't even notice. When he jumped out, he had an, "oh, $#%!" moment.

Operators are **** on rippers. There always seems to be one in the bunch that will find the going easy and speed up....

 

[Renze]

I must agree with everyone who says not to quench, the only time I have quenched is if the engineer has spec'd it in the weld procedure. Which has to this time been never. And as far as quenching between passes, that is a lot of thermal cycling before it ever sees a load. Quenching causes internal stress fractures at the microscopic level, and vibration and shock loading turn them into cracks, turning into a failure. Right now I build bridges, I have built trailers, been on a pipeline, and in most cases if the atmospheric temp is to low you have to pre and post weld heat treat them. And that includes mild steel. This question is best left for an engineer but my thoughts are if your going to invest time and money into something, let it cool and do it right the first time.

At my work, they payd for their lessons when they started using Naxtra 70 steels for payloader booms. I just copy the welding instructions to a new drawing, as it is based on (expensive) experience.

The effects of rapid cooling, rapid heating, becomes more dramatic when welding:
- high strength steels
- parts subjected to loads that make it critical to fatigue (alternating and/or dynamic loads)
- thick materials, that make them cool on the outside far quicker than the inside.

If they hadnt poured in cooling water tubes in the Hoover dam, the outer skin would have cracked because it would cure before the inner part of the dam, and it would have taken 125 years before the concrete would cure on its own. All because of the stresses involved of unequal temperatures between core and skin of a body.

 

[Transit]

The Japanese Katana is shock cooled. Some do not survive the shock, but it does work.

 

[killdozerd11]

The Japanese Katana is shock cooled. Some do not survive the shock, but it does work.

Not Even Close to the same thing

That is forge welding and you are bonding layers of hard steel to a core that is slightly flexible and it goes through a lot of heating and cooling processes both fast and slow before it is shock cooled to harden the edge that gives them there uniquely famous edge that is razor sharp but will still flex without breaking

I was in my younger years into kenpo and martial arts and read extensively about how a master creates those works of the blacksmiths / sword smiths art

What the uneducated don't know is that you cannot what is called dead cut with a katana ..it is not an axe if you do it can bend or break.

You must cut with a slicing motion either forwards or backwards when preforming the stroke or cut it takes time to learn.

Hence the demonstration of the guy walking on the blade of the katana
if you put it to your skin under pressure it wont cut you but if you slide even slightly it will sever it (sorry way off topic)

 

[Iplayfarmer]

(sorry way off topic)

...but way cool.

I saw a documentary about katana's and learned how the Japanese executioners were involved in rating a sword as a 3-body, 4-body etc. A little gruesome, but fascinating.

Back on topic: I was building a cart for my oxy/fuel outfit, and I shock cooled the plate that I was using as the back plate for the cart after cutting it by tossing in in the snow. I agree it may not be the best idea; but as ugly as this obviously homemade cart is, My heart won't break if this non-critical component cracks.

 

[killdozerd11]

...but way cool.

I saw a documentary about katana's and learned how the Japanese executioners were involved in rating a sword as a 3-body, 4-body etc. A little gruesome, but fascinating.

Back on topic: I was building a cart for my oxy/fuel outfit, and I shock cooled the plate that I was using as the back plate for the cart after cutting it by tossing in in the snow. I agree it may not be the best idea; but as ugly as this obviously homemade cart is, My heart won't break if this non-critical component cracks.

the topic was rapidly cooling a weld not what you cut

 

[Iplayfarmer]

the topic was rapidly cooling a weld not what you cut

Oh, right!! My bad

 

[JB4310]

Well on that subject, I don't have a problem with quenching flame cut pcs, don't know if it's good or bad, that could be a whole new subject

But I don't want to stress a welded connection. We do everything to prepare for the best possible results. Like fitting, grinding, proper rod, proper amperage, proper technique and the best process.
Like I said before, it just stands to reason, quenching isn't condusive with achieving the best possible results.

JB.

 

[20 20]

on cast iron I pre heat and weld with a 7018 rod then rap it with insulation to slow down cooling

Cast iron or cast steel? I use 7018 on cast steel but would not use it on cast iron.

 

[tugboat-2]

Ahhhh,..just before you go,... I have a brief comment someone might correct me on if appropriate?

Not welding but "hot metal related" : I was told years ago by a welder, that when sharpening my mower blades on a grind stone,...(and they certainly do get pretty hot),...he said to dunk 'em immediately in the water bucket to harden the metal.

He told me it takes more heat than a grinder to "harden" metals effectively, but that for a mower blade,...you should dunk it anyway for all the hardness it may acquire.

IF,...that statement is true, (and I tend to believe my welder), then it would indicate that "quick-water-cooling" tends to harden the metal. I have watched him cool welds and often in stages so it doesn't get brittle.

Any comments guys,..or gals?

CHEERS!
. . tug