Skyscrapers, exotic cars, rocket launches  - certain things just grab your attention.  Welding , apparently, is not one of them. You may have spent your entire life without ever thinking about the subject. You will surely be surprised by the fact that according to some estimates, welding affects as much as 50 percent of the gross national product of the United States of America. Without welding, none of those amazing skyscrapers, cars or rockets would exist.

Welding  is at its core simply a method of joining two pieces of metal together.  Although there are other ways to join metals (riveting, soldering...), welding has become the first choice because of its  strength, efficiency and versatility .

There are many different welding methods , and new ones are being discovered. Some processes use heat to essentially melt the two pieces of metal together, often adding "filler" to the joint to act as a bonding agent. Other methods rely on pressure to bond the metal together, and some use a combination of heat and pressure. Unlike soldering, where the metal parts being joined remain unchanged, the welding process always changes the material being joined.

This may seem somewhat unimportant, but it is crucial to understanding  why welding  produces such strong joints. In soldering and brazing processes, two pieces of metal are joined by introducing a third material (with a lower melting point) into the mixture. Adding that third material between the surfaces of the original pieces binds the pieces together. The bond, however, is only as strong as the bonding material. Welding, on the other hand, eliminates the middleman and joins the original pieces directly to each other. The result is a strong, cohesive bond that is often as strong as the material itself.

In this article, we will take a closer look at exactly how welding works . We will also examine some of the many situations where welding is used,with the expertise and equipment needed to make it all happen. But before we do, let's look at where it all started.

With all the machinery involved in welding processes, you may think of welding as a relatively new process. In reality welding has been around for thousands of years. Early examples of welding have been found in locations ranging from Ireland to India, with some dating back to the Bronze Age. Of course, these civilizations did not have the vast amount of tools and machinery that welders now have access to. How did they manage to weld?

The process they used is known as forging. To begin the process, smiths would heat the metal until it was bright red in color (but still not liquid). Blacksmiths would then place the two pieces, slightly overlapped, on the anvil and rivet them together. Riveting has several limitations. Only relatively soft metals can be riveted to each other and the process is very laborious. In places without electricity, however, the procedure is still used.

Forging was the only possibility until the 19th century. However, with the onset of the industrial revolution, numerous discoveries pushed the development of welding. Electricity research brought electrodes and electric arcs. Rudimentary torches were developed by the middle of the century. Both discoveries will significantly influence the welding methods of the next century.

By the late 1800s, welding was becoming the driving force in manufacturing. However, the methods of this era were not perfect. Oxidation (the process of metal bonding in oxygen particles in the atmosphere) occurred during the welding process and the welded joints were porous and brittle. Such welds pose a serious risk to workers. For example, during the period from 1895 to 1905, poorly constructed boilers exploded daily, causing thousands of deaths. There was clearly an urgent need for better welding methods. Below we will learn more about the new and improved methods, starting with a closer look at the specifics of the craft.

Welding at sea and in space
Diver welders routinely repair ships and oil rigs, usually using electric arc welding (negating the use of flame). Welding in space is at the other end of the spectrum. The vacuum of the space creates an ideal welding environment because there are no gases to interact with the welding spot. 
Welding outside the earth's atmosphere made the International Space Station possible.

Specifics in welding

How welding works
We are ready to start welding. Most welded joints today fall into one of two categories: arc welding and gas welding.

Arc welding  uses an electric arc to melt the work materials as well as the filler material for the welded joints. Arc welding involves attaching a ground wire to the welding material or other metal surface. The second wire is placed on the material to be welded. After the wire is slightly separated from the material, an electric arc is created. It looks like when you pull the ignition cables from the battery. The bow then joins the work pieces together with a filler material that helps to hold the pieces together.

Bringing the filler into the joint requires a steady hand and an eye for detail. As the rod melts, the welder must continuously feed additional material into the joint using small, sure motions. These movements are what give welds their special appearance. Moving too fast or too slowly, or holding the arc too close or too far from the material can create bad welds.

REL welding, inert gas welding (commonly known as metal inert gas, or MIG, welding) and tungsten arc gas welding (often called tungsten inert gas, or TIG, welding) are arc welding.

These three common methods have their advantages and disadvantages. Electrode welding, for example, is cheap and easy to learn. It is also slower and less versatile than some other methods. In contrast, TIG welding is difficult to learn and requires special welding equipment. TIG welding, however, produces high-quality welds and can weld materials that other methods cannot.

Gas welding is another popular method of welding. This process typically uses an acetylene/oxygen torch to melt the work material and welding rod. The welder controls the torch and the rod simultaneously, thus creating full control over the weld. While gas welding is less common in industry, it is still often used for maintenance and repairs, as well as on sculptures (more on that later).

„ Extreme Welding“
Red-hot electric arcs and torches are no child's play, but there are more extreme ways to weld. Explosion welding uses the pressure created by a powerful explosion to join metals together. Laser beam welding relies on powerful lasers to fuse metals together. Ultrasonic welding uses high-frequency vibrations that cause metal molecules to resonate and thus join together.

A good weld is hard to find
We can recall the history of welding and that brittle, porous welds have caused serious safety problems in industrial applications. Much of the problem with those first welds stems from oxidation. As the science of welding has advanced, so have the methods for protecting the weld site from oxygen. In electrode welding, for example, the electrode is coated with a protective coating. This protection has several different purposes, one of which is to create a gas shield for the welding point. MIG and TIG welding go so far as to use gas tanks that continuously envelop the welding spot in inert gases. Protection of the welding point from oxidation is essential for the formation of a strong weld.

The preparation process itself is perhaps just as important for producing strong welds. Ensuring that the work materials are free of grease, dirt and dust is only the first step in properly preparing the welded joint. Choosing the right type of joint is crucial for a quality weld.

After welding, you can check the quality of the weld in several ways. A visual inspection may show that the welder was working at the wrong speed or amperage, creating cracks and long irregularities. Welders can also control their work by magnetic particle testing, liquid penetration, ultrasonic testing, X-ray inspection, pressure testing, or other methods. Destructive testing, which destroys the weld in the control process, is also often used to determine weld quality.Regardless of which test is used, ensuring that the weld is strong and secure is an important step in the process.

Welding in industry and art
Most welding jobs are related to production in industries. Automotive industry, shipbuilding, commercial construction, bridge construction - the list of welding jobs goes on and on.

Although most welders are men, thousands of women make a living by welding. Women welders played key roles in shipbuilding during World War II.

One of the more interesting applications of welding comes from the artistic community. Some of the first examples of welding ever were works of art, such as the iron pillar of Delhi, India, and gold bowls and caps dating back more than 1,000 years. Structures like the arches of St. Louis Gateway (192 meters high and built to last 1,000 years) and Brussels' Atomium illustrate how far the art of welding has come.

The tradition of artistic welding remains strong, as welding creates massive sculptures that weigh several tons. Although artists make up only a small segment of the welding industry, they can show the potential of welding to millions of others.