The Basic Process of Welding

Although it bears a superficial, passing resemblance to soldering, welding is only slightly related to that far less effective (and far less involved) method of joining two pieces of metal together. Soldering employs a filler metal – solder – which is rarely of the same metal type as the workpieces being joined, and does not use enough heat to cause any melting of the two parts themselves. For this reason, it is only as strong as the solder’s grip on the unmelted metal surfaces, and is not suitable for high-stress applications.

Welding, on the other hand, is a much more intensive method and leads to a much stronger join between the two halves of the project. It is a good idea to know how welding works in general terms before making the first attempt to weld, because an understanding of the principles involved can both suggest ways to make the welding more successful and helps you know how to avoid mistakes later in your welding adventures.

Several special labels are applied to different elements involved in the welding process, which are employed in all welding literature, and these should be learned now to ease learning of new techniques in the future.

Base metal is the metal which is being welded – the two parts which are about to be joined into one unit through the welding process. Filler metal is metal introduced from outside the two pieces of base metal by the welder – usually in the form of a wire or rod fed into the welding arc or flame either mechanically or by hand. The weld pool is a small puddle of molten metal formed by the melting of both pieces of base metal and the filler metal, which occurs at the point in the seam that the welding arc or flame is pointed at directly.

Welding works by melting both pieces of base metal and the added filler metal – which is typically the same kind of metal as the base metal, unlike solder – into a pool of controlled width and depth. As the arc or flame is moved further along the join, the weld pool shifts with it, and the molten metal behind that point cools and hardens into a weld.

The weld literally blends the molecular structure of the two pieces of base metal together by liquefying them and allowing them mix, with the filler metal adding additional material to ensure a strong, thick weld rather than an attenuated one. Thus, a strong, lasting bond is formed between the two pieces of base metal, and once it has cooled and the weld bead has been smoothed properly, the finished workpiece should remain solidly intact for years to come.