One of the more unique forms of welding is Atomic Hydrogen welding or AHW. What makes this process so unique is that it is a combination of both gas and electric welding techniques that are used.
AHW is a Thermo-chemical arc welding process where multiple workpieces can be joined together through the use of heat. This heat is obtained when the stream of hydrogen runs through an electric arc that is placed between two tungsten electrodes. This process helps to prevent oxidation of the metal and it prevents the rapid burning of the electrodes.
The oxygen that is integrated into the process from the surrounding area helps to form water. It combines with hydrogen, helping to immediately become a stream. The remaining hydrogen that does not combine with the oxygen combines with carbon in the surrounding air, which creates a higher degree combustible burn.
The Basics of Atomic Hydrogen Welding
This welding process was invented by Irving Langmuir, who had been studying atomic hydrogen. We discovered that through the use of hydrogen gas, he could create a welding process that generated a great deal of heat, in excess of 4000°C. This made the third hottest type of flame of any welding torch, a significant advantage over most other types.
What Is Atomic Hydrogen Welding?
In the AHW process, the hydrogen acts as a shielding gas. This protects from elements in the atmosphere corrupting the weld, elements such as carbon, oxygen, and nitrogen. In fact, not only do these elements not corrupt the weld, but they actually act as an additional product that can help to increase the productivity of the weld.
Oxygen forms with the hydrogen, producing water. This is a byproduct that is then streamed to help in the cooling process. Carbon combines with hydrogen to form hydrocarbons, which is then burned and increases the heat generated by the weld.
One major advantage of using this type of weld is that it does not require a flux or filler. The amount of heat generated is enough to melt the metal so that when it cools it is able to create a proper seal in connection. This reduces costs and presents a quality. This is one of the sharpest looking types of welds you can produce.
What Type of Power Supply Is Needed?
Because of the way that the heat is generated, and equal supply of electricity to both ends of the electrode is essential. Without that equal supply, the process would not continue in the proper way. This could lead to elements contaminating the weld, or the weld not sealing properly.
To obtain the necessary power, an AC power supply is needed. In fact, where some welding processes can use either form of power to supply to the welding mechanism, this is not true with AHW. DC power supplies can never be used.
How to Generate Optimal Weld?
There are four primary factors that are necessary to control to make sure you get the proper weld. These include:
- The size of the arc.
If the arc size is too big, it may not properly heat the metals that need to be connected.
- The speed of travel.
The necessity to maintain these in the proper conditions is quite obvious when examined more closely. For instance, with speed of travel, if you are moving too quickly or too slowly across the weld, you can create conditions that challenge the structure of the weld.
A travel speed that is too fast will not allow the metal to properly melt. This could mean that the weld is not sufficiently stable. A travel speed that is too slow could create an area in the metal that has lost its strength.
- The setting of the current.
If the current is not strong enough, you may not reach the proper temperature needed.
- Ensuring the proper contact of the arc and the workpiece.
Not making the proper contact with the workpiece could corrupt the weld as well. To help with these particular issues, the AHW weld is offered as an automatic option. This allows the welder to set the specific conditions necessary to ensure that the weld will properly be created. Many find that this is the best option to ensure they get the same quality weld in each instance.
Advantages and Disadvantages
There are many advantages and disadvantages to this particular type of welding process.
- The welding process is much faster than other options.
- You are able to concentrate the weld at a specific joint, which means a greater decline in distortion.
- The hydrogen envelope prevents oxidation of the metal and the tungsten electrode.
- The workpiece does not become part of the electrical circuit, making it easy to move the metal to other places. This prevents problems, such as the striking of the arc or difficulty maintaining the arc column.
- There is no need for a separate flux and shielding gas.
- This type of weld is limited to the flat position.
- This type of weld cannot be used for the depositing of large quantities of metal.
- Other forms of welding offer a much greater speed in comparison.
Applications for Atomic Hydrogen Welding (AHW)
While travel speed is important, it is also important to recognize that this type of weld was created because the amount of heat generated allows the welder to create fast welts. Major Applications of Atomic Hydrogen Welding are:
- Joining parts, hard surfaces and making repairs.
One thing you will notice about this type of weld that is different from others is that there are not specific industries where you are likely to find AHW welds used. In some other types of welding processes, they are perfect for such things as the automotive industry or ship repair.
- For use with stainless steels and non-ferrous metals.
With this type of welding process, it can be used in a wide variety of industries, but specific types of metals and materials restrict its use. For example, only non-ferrous metals can be used, because the heat generated by the weld could cause oxygen to combine with iron to create rust. This would not be good for a weld.
- For welds that contain, tungsten, nickel and molybdenum.
In addition, materials such as tungsten, nickel, and molybdenum are ideal for this type of weld. Because they are metals that require high degrees of temperature to melt, the AHW is often the only option that can be used. This ensures that the proper weld is created while also not causing any damage to the metal surface.
What you are going to find is that the number one use for this type of welding process is when the metals that are used have high melting points, melting points in excess of 3000°C. This then lets you know where you will find the application.