sideffects of spatters why do they occur

[rohit rawat]

Hi there,
can anybody out there let me know the reason, why the
spatter occurs and is this akind of defect or we simply remove them
due to the asthetics.
Rohit Rawat

[Sam Malemela]

Weld spatter result from incorrect current settings. This has adverse
effects on corrosion protection coatings.
Weld spatter is cathodic to steel and as such becomes the propagation point
for corrosion.

NS MALEMELA
Contracts & Quality Manager [Special Projects]
Southern Pipeline Contractors
TEL:(011) 914-8519
FAX:(011) 914-4524
082 389 2592 Cell
smal...@spc.co.za

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[JASPAL SINGH]

Spatter is caused by several factors, the main factor being a
disturbance in the molten weld pool during the transfer of wire into
the weld. Typically this is caused by the relationship between
amperage and voltage. This is usually seen when the welding voltage is
too low or the amperage is too high for a given wire and gas
combination. In this situation, the arc is too cold to keep the wire
and pool molten and causes a stubbing effect of the wire. This can
occur at both high and low current ranges.

Other Factors are

1. In a short arc process, the weld droplet contacts the weld pool and
scatters the base metal before fusion.
2. When fusion occurs after short-circuiting and the weld bead heats
due to a large increase in current. This is essentially the problem
described above where the amperage becomes too excessive for the given
welding wire. This is also what most welders like to refer to as the
“arc explosion” or the popping that causes spatter.
3. An arc repulsion force causes the weld bead to break off and
scatter
4. Splashing occurs when a weld droplet falls into the molten pool.
This is very common in a globular transfer mode.
5. When the weld bead is affected by the magnetic repulsion force of
the short circuit in the weld pool.

Jaspal Singh, CWI-AWS, CSWIP-3.1
Quality Assurance
Process Equipment Division
ISGEC, Yamuna Nagar, Haryana -135001
Phone: 911732307251
Ext: 251 Mb: +91 9996624244

On Oct 6, 4:16 pm, "Sam Malemela" <smalem...@spc.co.za> wrote:
> Weld spatter result from incorrect current settings. This has adverse
> effects on corrosion protection coatings.
> Weld spatter is cathodic to steel and as such becomes the propagation point
> for corrosion.
>
> NS MALEMELA
> Contracts & Quality Manager [Special Projects]
> Southern Pipeline Contractors
> TEL:(011) 914-8519
> FAX:(011) 914-4524
> 082 389 2592 Cell

> smalem...@spc.co.za

>
>
>
> -----Original Message-----
> From: material...@googlegroups.com
>
> [mailto:material...@googlegroups.com] On Behalf Of rohit rawat
> Sent: Wednesday, October 06, 2010 11:24 AM
> To: Materials & Welding
> Subject: [MW:7394] sideffects of spatters why do they occur
>
> Hi there,
>            can anybody out there let me know the reason, why the
> spatter occurs and is this akind of defect or we simply remove them
> due to the asthetics.
> Rohit Rawat
>
> --
> To post to this group, send email to material...@googlegroups.com
> To unsubscribe from this group, send email to
> materials-weld...@googlegroups.com

> For more options, visit this group's bolg athttp://materials-welding.blogspot.com/

> The views expressed/exchnaged in this group are members personel views and
> meant for educational purposes only, Users must take their own decisions

> w.r.t. applicable code/standard/contract documents.- Hide quoted text -
>
> - Show quoted text -

[M. Ali]

Dear Rohit,

The reasons why these spatters occur are numerous like
1. High Current - Low Voltage
2. Long arc length
3. Damp electrodes
4. Wrong selection of shielding gas etc.

but spatter is a cosmetic imperfection and does not affect the
integrity of the weld. Its a sign that the welding conditions are not
ideal. But they are always produced in the open arc consumable
electrode welding process.

The removal of spatter sometimes becomes necessary because
1. They are a hinderance in the proper adhesion of coating (if
applied)
2. As already pointed out by Mr. Malemela, they are somewhat cathodic
to the base metal.
3. In case of tank bottoms weld seams that have to be vacuum tested,
they give false indications or may be right on top of a pinhole or may
even scratch the seal of the vacuum box.

Hope this helps

Regards,

M.Ali