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steel preheating

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Toyotanut

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I don't understand the whole reason behind preheating steel when welding pieces together. For example I have a friend who I'm going to do some some welding for. It's just mild steel 1/4" to 1/4". His brother who has supposedly been welding for the last 10 years told me that I should preheat the steel first. The welder I'm using is a mm175 with er70s-6 .030 diameater filler, and a 75/25 gas mix. What is the reasoning behind preheating and is it necessary for me to do?
 
not on mild steel...

on other types of steel its required such as HY-80. if not it will crack. it also needs to be cooled slowly....

when welding "cast" steel it is suggested to preheat to about 200 degrees.

basaically there is a process for welding any configuration of metals and all have differing requirements due to the metalurgy properties of the particular materials.

for ms to ms just weld it.

short and sweet answer ok for ya?
 
Hip said:
not on mild steel...

on other types of steel its required such as HY-80. if not it will crack. it also needs to be cooled slowly....

when welding "cast" steel it is suggested to preheat to about 200 degrees.

basaically there is a process for welding any configuration of metals and all have differing requirements due to the metalurgy properties of the particular materials.

for ms to ms just weld it.

short and sweet answer ok for ya?
Click to expand...

Kinda what I thought. Friends brother said that the mm175 wouldn't get enough heat and penatration and that I should preheat.

When preheating, what do you do? Use the oxy/acet to preheat or is there another method to use?
 
Toyotanut said:
Kinda what I thought. Friends brother said that the mm175 wouldn't get enough heat and penatration and that I should preheat.

When preheating, what do you do? Use the oxy/acet to preheat or is there another method to use?
Click to expand...

any torch that makes heat works, that probably your fastest method. what in the hell is he using mild steel for that is so load bearing anyways? Grind in a fillet and weld it together. If his brother is some big welder full of opinion's, tell him to do it himself.
 
I do like to heat the steel just to cook out an moisture that may be in the steel as my garage is very damp, but I wouldn
 
Toyotanut said:
Friends brother said that the mm175 wouldn't get enough heat and penatration and that I should preheat.
Click to expand...
He's right, the MM175 is a hair light for 1/4" material, but unless you need the absolute strongest weld possible, it'll get close enough without pre heat.
 
darius said:
any torch that makes heat works, that probably your fastest method. what in the hell is he using mild steel for that is so load bearing anyways? Grind in a fillet and weld it together. If his brother is some big welder full of opinion's, tell him to do it himself.
Click to expand...

as far as I know it's some rectangle toob that's being used for a frame and all the mounts to the frame. That's what I was thinking grind in some fillets and weld it up...

but obviously I'm no welder by trade and doin this for 10 years. Guess I better listen to him then and stick to my locks
 
Hip said:
not on mild steel...

on other types of steel its required such as HY-80. if not it will crack. it also needs to be cooled slowly....

when welding "cast" steel it is suggested to preheat to about 200 degrees.

basaically there is a process for welding any configuration of metals and all have differing requirements due to the metalurgy properties of the particular materials.

for ms to ms just weld it.

short and sweet answer ok for ya?
Click to expand...

:awesomework:

That pretty much sums it up... The pre-heat and post welding heat treatment are dictated by the material composition and the desired material properties...

With mild steel you don't need to worry about preheating or the welding method you use... just make it penatrate!
 
Binder said:
Filet does just that....I always get a kick when I read things like this. Tells me the person who started this has never worked in the field before.
Click to expand...

You are right, I've never personally worked in this sort of profession. I'm just trying to help educate myself, so as to make sure I am doing things correctly. Thanks for the help doggggg:flipoff:
 
Another reason you would pre-heat in this situation is because what your welding on. Frames for example, will pull when welded if your not careful. Preheating helps remove any stresses in the metal prior to welding. Post heating will help normalize the steel.

We commonly weld T1 and AR400 plate at work. We heat AR400 to 350° prior to welding. On A36 (mild steel) I typically run a rose bud around the weld area to sweat out any moisture, and it also cooks any grease, oils, etc off so you have a clean weld with no contaminates.

With the welder being used, I wouldn't take any chances and preheat, since it is a critical component.
smilie_schweissen.gif
 
CrustyJeep said:
He's right, the MM175 is a hair light for 1/4" material, but unless you need the absolute strongest weld possible, it'll get close enough without pre heat.
Click to expand...

AWWWW BULLSHIT!!!!!!!!!!!!! A welder who is worth a **** will not have an issue with a 175:looser:
 
If I was welding on someones rig, preheating should be the last thing they wory about. Picture the boogers holding the pieces together. :redneck:
 

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