Kobatek 250


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General Description

Especially for welding cast aluminium alloys containing more than
7 % Si as main alloying element.

It is ideal for repairing of cast defects and for the fill up of cast cavities.

Also applicable as surfacing electrode.

Good weldability, no porosity.

Applicable when Al-properties are unknown.


Classification and Typical Weld Metal Composition

AWS A5.3 : E4047
ISO 18273
: Al 4047A (AlSi12(Al))
Al Si Mn Fe Mg  



< 0,10

< 0,40

< 0,05



Mechanical Properties of the Weld Metal, Typical

Yield Strength : 80 (N/mm²)    
Tensile Strength : 170 (N/mm²)    
Elongation (L=5d) : 6 (%)    

Approvals and Certificates





Applications and Materials to be Welded

It is an ideal electrode for the welding of 12 % Si containing cast aluminium parts. It should not be used in the welding of aluminium alloys having high magnesium, copper or zinc content. The special covering removes oxide layer on the surface during welding and enables a stable arc. As the weld pool metal is very fluid, parts should be welded in horizontal position. During welding, electrode should be vertical to the work piece and it should not be oscillated.

Preheating to 100-300°C should be applied with respect to the thickness of the part to be welded. The slag should be removed completely after welding, since it is corrosive (the slag might be removed with water as the piece cools).

Aluminium Cast Alloys:
G-AlSi12 (413.0), G-AlSi12 (Cu), G-AlSi10Mg (361.0), G-AlSi10Mg(Cu)
G-AlSi9Mg (359.0), G-AlSi9Cu3, G-AlSi7Mg (356.0), G-AlSi6Cu4 (319.0)

Welding Parameters / Packing and Diameter Informations

Current Type and Polarity : DC (+)

Electrode Weight
(g/100 pcs)
2.50 350 60 - 90   980 204 2
3.25 350   90 - 110 1320 152 2
4.00 350 100 - 140 1960  102 2

Welding Positions


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