Cooling welded connection

[Inkomodius]

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.

 

[mechanic]

Using water on your welds will make them brittle. If it something critical don't use water. it will weaken your weld. Doing weld test in school we always laid the welded metal on the concrete floor and let cool on it's own.

 

[20 20]

This is just a question I have. I seen some people to cool down welded piece by dumping it in water to be able to work on it sooner.
I always feel it should cool down on it's own.


What do you think?

I allways thought this was a good idea NOT! If it is just a simple weld I'll let it cool on its own. You'll be running the risk of crack welds/metal. I did have to weld a track pad on my dozer once and actually had to put it on a flame for a couple of hrs. Then slowly turn the flame down, that weld has held great with no cracks.

 

[schmism]

small brackets and BS stuff i usually dump in a bucket so i can wire brush them, and paint them and have them in service in 5 min.

on the other hand when i welded my bucket teath on, i preheated both the bucket area and tooth, welded and again used heat to keep it warm while i beat on the weld with a ball peen for 2 min

 

[killdozerd11]

small brackets and BS stuff i usually dump in a bucket so i can wire brush them, and paint them and have them in service in 5 min.

on the other hand when i welded my bucket teath on, i preheated both the bucket area and tooth, welded and again used heat to keep it warm while i beat on the weld with a ball peen for 2 min

Backhoe teeth can only come off when back stroking the bucket they only push tighter on there mount's when digging and your going to have to grind those welds off when the teeth are replaced so your going a little overboard.

Most buckets use pins to retain teeth on there mounts
so when the operator has to replace them only require a hammer and punch and maybe a pair of vice grips and a few minutes

Instead of a welder, grinder, etc and a lot of minutes
It took me awhile to get my father to see this fact but even he finally came around

But back to the subject if the weld is something NON stress cool it fast if you want
But if it is going to be under any kind of stress i don't advise it

When i took my my certs we were not permitted to do any thing with our coupon once you turned it in for testing you could do anything you wanted to a practice coupon but not your cert coupon and i never seen anyone dunking there coupon in water

 

[ihuntbear]

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

 

[killdozerd11]

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

On castiron ?????????????????? 7018 ??????????

NI-rod / Beryllium copper / Brazing. Yes.... been there done that

But 7018

 

[schmism]

ok to be technical.... bucket teeth shanks were welded

the teeth themself are pin on.

Most buckets use pins to retain teeth on there mounts
so when the operator has to replace them only require a hammer and punch and maybe a pair of vice grips and a few minutes

 

[killdozerd11]

ok to be technical.... bucket teeth shanks were welded

the teeth themself are pin on.

DUHHHH
The factory usually uses a welded on type of mount.... yes
though i have seen a few that were bolt on

As far as teeth most use spring pins of one type or another but i have seen teeth that mounted with a dimple formed on the tooth and the mount mostly on tractor rippers but those don't work well at all

If you hit them going back wards for any reason they come off
But even the ones on dozers that are pinned on will come off with to much back force and cat teeth and pins are not cheap

I grew up with 2 backhoes and a lot of other equipment and trucks and tractors
Then went into the Operating Engineers now i'm semi retired
Been around the block a couple of times

 

[Transit]

Shock cooling is not a good idea. I have seen shock cooled weldment shatter like glass.

 

[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