Why Slag comes on top of weld bead & if ur answer is related to density th

Why Slag comes on top of weld bead & if ur answer is
related to density then think of overhead welding if slag
is ligter than weld metal then in overhead welding firstly
a laye of slag & then a layer of weld metal must be
deposited.

Question Posted / rakesh2mittal

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Why Slag comes on top of weld bead & if ur answer is related to density then think of overhead..

Answer / devanathen l k

Because of molecular attraction and cohesion between the
molten base metal and deposited weld metal, they bind (fuse)
to each other and the flux, which is a non-metal, gets
ejected from the weld and deposits on the top of the weld bead.

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Why Slag comes on top of weld bead & if ur answer is related to density then think of overhead..

Answer / rakesh mittal

Two possible reasons may be
1) Solidification time of Slag being more than base metal so base metal solidifies first, where as slag being in liquid state comes to open area
2) Impurities moves toward hotter region as weld pool start solidifying heat transfer via conduction from base metal(being good conductor of heat)is more than heat transfer via convection between open area of weld pool in contact with air so base metal solidifies first and slag moves towards hotter region so slag moves toward open area it may be up as well as down the bead,that's why slag observed on root side as well as face side of bead

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Why Slag comes on top of weld bead & if ur answer is related to density then think of overhead..

Answer / pratik patel

That slag is nothing but the FLUX, Welding rods are covered
with flux, in TIG & MIG welding this function is done by
INERT gas. The function of FLUX is to cover the heated
(welding) zone and to prevent contamination of it with
outside air.

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