Too much heat will likely cause cracking in the weld, oxide inclusion, softening of the heat-affected zone, and porosity—all of which degrade your material and affect the quality of your weld, both structurally and cosmetically.
You will have undercut on the toes of the weld and the weld puddle will be too hot to control and will usually be crowned up in the middle. Another clue is if you burn a rod down to about 3 inches long and your stick welding rod is glowing red, you are too hot.
Uncontrolled cooling can lead to many problems both within the weld and in the base material. Rapid cooling produces smaller, finer grains in the metal's microstructure, while slow cooling produces larger, coarser grains. Excessively high or low cooling rates decrease the metals' crack resistance.
When welding certain alloy steels heat input is critical… overheating the metal will result in destroying the desirable properties of the metal. Duplex stainless steel and titanium immediately come to mind; as too much heat completely ruins the material.
Excessive heat is the main cause of burn-through, and this can be fixed by reducing voltage or wire feed speed. Increasing travel speed may also help, particularly when MIG welding on materials especially prone to heat buildup like thin aluminum.
About flash burns
That's why it's sometimes called 'welder's flash' or 'arc eye'. Flash burns are like sunburn in the eye and can affect both your eyes. Your cornea can repair itself in one to two days, and usually heals without leaving a scar. However, if the flash burn is not treated, an infection may start.
Treatment for flash burns may include: Dilating drops – these are sometimes used to relax the eye muscles, which in turn eases pain and allows your eyes to rest and heal. Your pupils (the black part of the eye) will look bigger than normal. This effect lasts several hours to a few days.
Many metals will change colors as a result of overheating. Also, metal coatings can be damaged or destroyed as a result. Electrical properties are typically altered when metals are overheated, although they usually return to normal once the metal returns to regular temperatures.
Some examples of material combinations that cannot be fusion welded successfully are aluminum and steel (carbon or stainless steel), aluminum and copper, and titanium and steel. Nothing can be done to alter their metallurgical properties. That leaves changing your process.
Freezing temperatures will cause your welds to cool much faster which can cause cracking and a lack of adequate penetration. Cold weather also means a bigger difference in temperature between your weld and your work piece. This can cause severe warping. An easy solution is pre-heating.
Not only the welding torch itself, but also all equipment and parts connected to the cooling circuit or cooling system are exposed to electrolysis and can be destroyed over time when using water as a coolant. Water in such a system can cause malfunctions and loss of efficiency up to total failure.
A good weld should be visually appealing, with a smooth and uniform weld bead that shows proper fusion and penetration. Bad welds, on the other hand, may contain defects like porosity, pinholes, or slag on the weld surface, which can compromise the strength and reliability of the weld.
Any kind of debris, dirt, oxides, or other particles on the metal will disrupt the weld, creating a final weld that is porous and not uniform. Since any porous nature in the weld means pockets of weakness, you want to avoid anything that will result in a porous weld.
Not recommended for most welding that I know of. With some steels, like high-carbon and tool steels, quenching with water can make them so hard and brittle and full of internal stresses that they will explode all by themselves within a few minutes of quenching.
Re: Dipping hot weld joints in water
So long as they are welding mild steel it is technically fine. This is because there is not enough carbon in mild steel to harden. Getting into higher carbon, tool, or spring steels is another thing entirely. The problem comes about primarily with A-36 steel.
Signs of a bad weld include: Burnout, no filler metal used, wide flat bead without distinct bead pattern, erratic beads, tungsten inclusion, porosity and/or undercutting.
Aluminum. The first impression of aluminum is that since it is pliable and easily manipulated, it should be easy to weld. In reality, it is considered to be the most difficult metal to weld since it is an alloy and therefore mixed with other metals. Some have even called welding with aluminum a “nightmare.”
TIG welding is the hardest form of welding to learn for a variety of reasons. The process of TIG welding is slow and takes time to get used to as a beginner. A TIG welder requires a foot pedal to feed the electrode and control the variable amperage while maintaining a steady hand at the welding torch.
Welding joins metals by melting and fusing them together, typically with the addition of a welding filler metal. The joints produced are strong – usually as strong as the metals joined, or even stronger. To fuse the metals, you apply a concentrated heat directly to the joint area.
The strength of steel remains essentially unchanged until about 600°F. The steel retains about 50% of its strength at 1100°F. The steel loses all of its capacity when it melts at about 2700°F. However, for design purposes, it is usually assumed that all capacity is lost at about 2200°F.
The slower the cooling process, the more austenitic grain structure will remain, providing a soft material with good ductility but lower strength. A very fast cool produces a total martensite grain structure, making a product high in strength but not ductile.
Some of the very hard wear plates found in industrial applications (near diamond hard) will begin to soften at 280° to 350°F. You can cook a pork butt at 280°F. In very general terms, if you have a very hard piece of steel that will be exposed to elevated temperatures, there is a good chance it may soften.
Metal fume fever
Many welders get flu-like symptoms after welding. The effects are often worse at the start of the working week. Metal fume fever is usually linked to welding or hot work on galvanised metals. High exposures to mild steel weld fume can also cause this illness.
Flash burns feel like sunburn in your eyes and is caused by bright ultraviolet (UV) light If you experiencing symptoms of flash burn, see medical attention and follow instruction. Untreated flash burns can cause infection and permanent eye damage. Always use a recommended AS/NZS welder's visor when welding.
Welding sunburns are a real thing, and they can cause everything from slight discomfort to severe pain to skin cancer. Prevention includes sunscreen, long sleeves, pants, gloves, and a welding helmet.