Welding Process Explained

The process of welding is essentially at the core of a gamut of things we see around us. If it were not for welding, the vehicles we move about in, the towering skyscrapers we behold, and the electric and electronic appliances we use, to name a few, wouldn’t have been the way they are! As a matter of fact, welding is one of the most indispensable journeyman trades all over the world.

The process of welding which entails conjoining two pieces of metal is a skill that, when clubbed with the right set of welding accessories, can easily be honed with the passage of time. However metals, by virtue of their dynamic properties, often pave the way to a lot of unanticipated twists and turns during weld bead formation. Even the most skilled and experienced of welding tradesmen fall victim to some rather intermittent welding defects at the slightest aberration from the regular welding procedure.

List of Most Common Welding Defects You Need to Take Care and Prevent Them from Occurring

Here are a few of the most common welding defects that you need to be on the lookout for and ways to prevent them from occurring:

1. Fibrous Structures

Fibrous structures are defined as anomalies found in the fractured part of the weld metal. The columnar structures are formed if the metal used is inferior in quality or cools down at a rate that is faster than normal.

Prevention: The formation of fibrous structures can be prevented by selecting a compatible electrode for use with the base metal. Also, preventing the weld metal from cooling down swiftly can help avoid the formation of fibrous structures.

2. Cracks

Even a single crack in the weld qualifies as a defect. Cracks usually result from metal shrinkage which, in turn, is known to happen when the freshly welded metal cools down to room temperature. Cracking can be categorized as hot cracking and old cracking. The former is known to appear inside the weld, especially in metals with traces of sulphur or a poor fit-up design; the latter is known to occur within a day or two of welding and is often hydrogen-induced.

Prevention: Crack formation can be curtailed by restricting the use of surplus current and preheating rigid joint. The use of low-hydrogen electrodes can prevent old cracking of the weld.

3. Blowholes

Blowholes are defined as sub-surfaced porosities that are seated inside the weld.  These blowholes do not extend up to the surface of the weld and are enclosed on all sides by the conjoined material.

Prevention:  The use of appropriate welding accessories and equipment can reduce the formation of blowholes manifold. Ensuring proper arc length also helps reduce the occurrence of blowholes. Besides, cleaning base metals out tidily and ridding them of any rust, oil and moisture also have a significant role to play in blowhole prevention.

4. Fish Eyes

Fish eyes can be defined as silvery-grey formations that appear in the fractured parts of the weld metal.

Prevention: Fish eyes can be prevented by curtailing the rapid cooling of weld metals and ensuring that the welding electrodes being used have not absorbed any moisture in them.

5. Slag Inclusion

Slag is a collective term for elongated lines that run along the length of the weld; they may be continuous or discontinuous in nature.

Prevention: The welding current and welding speed should be adjusted in an appropriate manner to curtail slag formation. Needless to say, the use of proper electrodes is also a necessity.