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welding and cracks?
t.j. - 25/5/06 at 09:24 AM

Q. I welded some of the Fe360 2mm with a mig 130A. the weld looks ok.
Then a used a small grinder to flatten the surface. I noticed some small cracks.
What did i wrong?? Or is it normal to have cracks at the zero-surface?

grzt

MikeR - 25/5/06 at 10:02 AM

whats fe360 ?

cast iron ?

t.j. - 25/5/06 at 10:20 AM

quote:
Originally posted by MikeR
whats fe360 ?

cast iron ?


Fe360= St37-2 = S235JR ,
don't know any GB-standards

[Edited on 25/5/06 by t.j.]

tks - 25/5/06 at 10:54 AM

Is the normal cheapest iron.

Norm: EN 10027-1 its S235

Norm: EU 27-74 Fe360

To make a weld that wonīt go away when you use the grinder donīt apply material only heat up the union and melt it together.

Tks

RazMan - 25/5/06 at 11:39 AM

quote:
Originally posted by tks

To make a weld that wonīt go away when you use the grinder donīt apply material only heat up the union and melt it together.

Tks


That's a bit difficult with a mig

t.j. - 25/5/06 at 12:01 PM

quote:
Originally posted by tks
Is the normal cheapest iron.

Norm: EN 10027-1 its S235

Norm: EU 27-74 Fe360

To make a weld that wonīt go away when you use the grinder donīt apply material only heat up the union and melt it together.

Tks

?????
Ok, with other words: welding with acityleen would be better? Takes more time and skills though.

So is it normal by mig-welding that there are cracks in de weld or not?? If not, how can i avoid it?

Peteff - 25/5/06 at 12:38 PM

Are they cracks or are you undercutting the weld? You shouldn't need to grind that much of the weld away. Try not holding the gun so steep when you weld.

NS Dev - 25/5/06 at 02:14 PM

more to the point why are you welding it??

Not something I would choose to weld

tks - 25/5/06 at 04:19 PM

sorry thought he mentioned TIG.

When welding MIG you should try to create a flat weld, settings needed are hot,

sow high amps and high flow, high speed of movement.

altough its difficult...

if you are welding to colt it will be more wire shape..

regards,

Tks

p.s. the cracks are normal its because you take away the weld, the place where no crack is is penetrated i would buy a Tig

[Edited on 25/5/06 by tks]

t.j. - 25/5/06 at 07:00 PM

quote:
Originally posted by NS Dev
more to the point why are you welding it??

Not something I would choose to weld


I build my frame out of 25x25x2
Ok it's heavier but who cares.

I understand that little cracks are caused by the high temp. I will use the grinder less Just wanted to know before i drive and my frame falls apart.

Thanks, i will sleep better now.
Ps. how much weight will it be more because of my choice. Anyone?

JoelP - 25/5/06 at 07:11 PM

upping 1.6mm to 2mm would be about a 25% increase in weight. Maybe 25kgs? I dont know what an average chassis weighs.

907 - 25/5/06 at 07:27 PM

14 kg's

Err, I think.


Paul G

zetec7 - 26/5/06 at 04:52 AM

I found that turning down the wire speed and welding slower gave enough penetration to cure that problem - really work the puddle into the base metal...

kreb - 26/5/06 at 02:04 PM

A couple notes: Only grind the weld flat if you really have to. Otherwise leave it a touch convex. In working with material this thin, it'd be very easy to take off too much material and end up with a weak joint. Likewise with a TIG, it's rare that you're gap-free. In trying to blend the material you're likely to end up with thin spots. For something structural I always add filler.