Yes that Cracker welded the slag Hammer>
Slag is the residue left on a weld bead from the flux. It shields the hot metal from atmospheric contaminants that may weaken the weld joint. Slag can also be globules of molten metal that are expelled from the joint and then re solidify on the metal surface. in either case, they are usually chipped away with a slag hammer.
it's not. Welders do use a chisel/hammer to knock the slag off, but a wire brush will do the same thing. Some welders do use a hammer to align their fit-up when the tack is still hot, but not after they have welded. If the slag is left on, it may cause expedited corrosion, this is why it should be cleaned, but in most top quality shops - a wire brush is used. It is necessary to hammer a weld joint after welding CI to CI as the induced stress are relieved to a large extent and also the cracking can be avoided in case of CI
Porosity is the most common weld defect. For beginners don't rule out lack of penetration and non-compatible welding rod or filler wire. It all depends on how the weld failed if it has. Proper prep and preheat is required in many types of welding. So a little more detailed question can help me give you a more detailed answer. Trapped slag is also a common problem. It creates a void in the weld. Although porosity is the most common defect some porosity doesn't necessarily affect the weld strength.
Correct current,travel speed, electrode angle, arc length
PWHT is a form of stress relief, other forms can be as simple as smacking your structural weld with a hammer. PWHT re-aligns metallic molicules (face centered) to similar configurations as before rapid heating and cooling occured.
Slag is the residue left on a weld bead from the flux. It shields the hot metal from atmospheric contaminants that may weaken the weld joint. Slag can also be globules of molten metal that are expelled from the joint and then re solidify on the metal surface. in either case, they are usually chipped away with a slag hammer.
The slag in the welding process protects the weld from oxidation and slows down the rate at which the weld cools. It also prevents brittleness of the metal.
Slag inclusions are nonmetallic solid material entrapped in weld metal or between weld metal and base metal. Slag inclusions are regions within the weld cross section or at the weld surface where the once-molten flux used to protect the molten metal is mechanically trapped within the solidified metal. This solidified slag represents a portion of the weld's cross-section where the metal is not fused to itself. This can result in a weakened condition which could impair the serviceability of the component. Inclusions may also appear at the weld surface. Like incomplete fusion, slag inclusions can occur between the weld and base metal or between individual weld passes. In fact, slag inclusions are often associated with incomplete fusion. Daniel
Correct current,travel speed, electrode angle, arc length
Slag is normally seen as elongated lines either continuous or discontinuous along the length of the weld.
Remedies to prevent slag inclusions - Avoid atmospheric contamination using proper welding procedure e.g. adequate Shielding Gas Proper removal of slag from weld bead surface using wire brush Redesigning the weld joint to permit sufficient space for manipulation of the puddle of molten weld material
IN SAW WHY SLAG OCCURS?
it's not. Welders do use a chisel/hammer to knock the slag off, but a wire brush will do the same thing. Some welders do use a hammer to align their fit-up when the tack is still hot, but not after they have welded. If the slag is left on, it may cause expedited corrosion, this is why it should be cleaned, but in most top quality shops - a wire brush is used. It is necessary to hammer a weld joint after welding CI to CI as the induced stress are relieved to a large extent and also the cracking can be avoided in case of CI
Too long an arc length allows the arc to wander creating a poorly shaped weld. The slag is usually too thin and can allow Oxygen in the air to attack the molten puddle which causes Porosity in the weld. Too short an arc length buries the slag and creates less heat which traps the slag and impurities. Keep in mind that electrode coatings help determine the correct arc length.
Welder slag is a byproduct resulting from the welding process, often forming a layer on top of the welded joint. It consists of the residue from the flux used in the welding rod or wire, which helps protect the weld pool from impurities and contaminants while it cools. Slag is typically removed after welding to inspect the quality of the weld and ensure proper fusion.
Partially by the smoke that is produced. This helps to keep the surrounding air away from the puddle. Mostly by the slag that covers the weld almost immediately as the arc moves on.
The following techniques can be used to prevent slag inclusions: Use welding techniques to produce smooth weld beads and adequate inter-run fusion to avoid forming pockets to trap the slag. Use the correct current and travel speed to avoid undercutting the sidewall which will make the slag difficult to remove.