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Heat sensitive?

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Heat sensitive?

Postby olek » Sun Jul 16, 2017 7:51 am

What mean 'making it heat sensitive' when welding thin steel?

Does it mean that if one use too much heat, the steel will soften and be more heat reactive for the next beads (case of square tubing for instance)?

Thank you.
Last edited by olek on Sun Jul 16, 2017 9:39 am, edited 1 time in total.
Pianos , restorer and tuner (technician)
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slowly learning ;) not complaining of doing beads and beads

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Re: Heat sensitive?

Postby Poland308 » Sun Jul 16, 2017 9:09 am

Depends on the context it's used in. Your suggestion is one possibility. Another one is that it may become prone to micro cracks when exposed to heat afterwards.
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Re: Heat sensitive?

Postby olek » Sun Jul 16, 2017 6:39 pm

Poland308 wrote:Depends on the context it's used in. Your suggestion is one possibility. Another one is that it may become prone to micro cracks when exposed to heat afterwards.
.3

Thank you,

I wonder something about the slag

My feeling is that too low heat makes a poor cooking of the slag and it does not fall easily, as I could verify when trying to use a high level of heat and seeing the slag peeling well suddenly.

What is the cause for the slag not falling easily ? I tend to confound slag not cooked enough, with porous zones, with "burned" slag due to too much heat.
Or may be simply because I did have thin steel today, the bright red zone did tend to be too large and last too long (with a higher amp, I am obliged to go faster and to cool the bead, and this is enough to avoid gluing of the slag)

When lowering amps today (very small bright red part soon gone at the end), I expect the slag to fall by itself at some point, but it does not work that way apparently.

is it really a "cooking" of the slag (from the heat at the surface of the metal) or mostly a mechanical process between the metal and the slag, for instance with enough heat the metal grows then retracts while the slag does retract less ?

Making little circles while welding make an easy falling slag , maybe because the heat is well distributed evenly then ?
Or is the efficiency of the gas protection having a major role there (stick inclination)*and arc lenght)

With 'triangle' or 'Christmas tree', progression, is the slag à little more entrapped?

If you understand what I mean .. Thank you sorry for the lengthy posting but I give much details hoping to be understood better...
Pianos , restorer and tuner (technician)
Dedicated to learn stick welding since april
slowly learning ;) not complaining of doing beads and beads

pro inverter PROGYS 200 FV PFC CEL+tig lift & end of gas regulation
olek
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Posts: 168
Joined: Sat Jun 03, 2017 4:07 pm
Location: France

Re: Heat sensitive?

Postby Poland308 » Sun Jul 16, 2017 7:15 pm

High or low amps is a possibility for slag not coming off easy. Trying to chip it off before the weld has time to cool is another, slag is designed to stay attached to the weld until it drops below a certain temp. Poor metal quality I.E. lots of surface rust or mill flake, or just low quality steel can also contribute. I recommend you get some heavy plates to practice with. 3/8 or 1/2 inch thick. No shorter than 6 inches and no less than 4 inches wide.
I have more questions than answers

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Re: Heat sensitive?

Postby cj737 » Sun Jul 16, 2017 9:32 pm

I would also add that despite the amperage setting, a "long arc" tends to create a difficult to remove slag. In my experience, I run in the hot edge of the limit and get slag that almost peels off by itself if I've run a really good weld. Worst case, I use the flat side of the hammer and scrape along the weld and get better removal than pecking at it.

But Poland gave you very accurate info that may help guide you technically.
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Re: Heat sensitive?

Postby olek » Mon Jul 17, 2017 8:08 am

Thank you , I 'd like to suspect too thin and poor quality metal, as I was surprised , the slag had a good look but some was entrapped
https://photos.app.goo.gl/RFOmeqY5qfAvaHyz2

Good recomandation form Josh indeed, new steel is frankly too expensive but I will find new sources for small pieces of good quality and thickness.

low heat did also favor that, I did test with a thicker 1/8 rod and 115A, and it burned a little some slag, and the slag did peel off correctly.

Can we envisage to use high amp to burn some entrapped slag, assuming it is thin enough and not too deep ?

I did notice that I find much easier to control the arc and have a "feel" for what is going on, with the dig function at its lowest (10% , may be I will pursue with the dig function off just for training purpose, then I will reinsert dig function when I will feel necessity for, and also to understand the arc behavior difference, something I feel I am beginning to understand)

Do you regulate that "dig " function (when possible, I have seen it on some professional welders) depending of the job, or depending of the electrode type ? Or is it a part of the arc behavior you are used to so it is kept at all times, I never seen videos on that point)

regards
Pianos , restorer and tuner (technician)
Dedicated to learn stick welding since april
slowly learning ;) not complaining of doing beads and beads

pro inverter PROGYS 200 FV PFC CEL+tig lift & end of gas regulation
olek
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Re: Heat sensitive?

Postby olek » Mon Jul 17, 2017 7:00 pm

I just did see that one can weld 7018 3/32 at 60 65A if the metal is soon saturated with heat

I tend to be afraid of lowering amps a lot, but I see well my beads deform, overheated,

I wonder if DCEP, low amp 60A, could be a solution with the 6013 even if they are not intended for DCEP originally

raising the hot start to a longer time (80% may be) so to obtain soon enough the wanted heat.

something to try

?
Pianos , restorer and tuner (technician)
Dedicated to learn stick welding since april
slowly learning ;) not complaining of doing beads and beads

pro inverter PROGYS 200 FV PFC CEL+tig lift & end of gas regulation
olek
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Posts: 168
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Location: France

Re: Heat sensitive?

Postby olek » Sat Jul 29, 2017 7:36 am

Hi !
)
I seem to notice that it was easy to get undercut when I used the back of a cross block that was not very thick ( 2x 1/8)

Could it be that the much heated metal is now very soft and sensitive to heat ? (proof in the pudding !)

Best
Pianos , restorer and tuner (technician)
Dedicated to learn stick welding since april
slowly learning ;) not complaining of doing beads and beads

pro inverter PROGYS 200 FV PFC CEL+tig lift & end of gas regulation
olek
Guide
 
Posts: 168
Joined: Sat Jun 03, 2017 4:07 pm
Location: France


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