Autogenous Welding definition
Autogenous welding is a technique of fusion welding process where welding is performed without the welding electrode or filler material. Note to mention that Autogenous welding is not similar to SMAW, GTAW, or MIG/ MAG etc.; but instead, it is one of the techniques of the existing fusion welding processes. Solid-state joining processes such as friction welding, friction stir welding, explosive welding are also autogenous welding methods because they work without the application of any filler metals. Autogenous welding is very beneficial for welding thin sheet metal as this will produce very low heat input.
What is Autogenous TIG Welding?
TIG welding when used without externally supplied filler wire is known as Autogenous TIG welding. This technique is used for welding thin metals, making temporary tacks during fitment. One of the most important uses of Autogenous TIG is for TIG refusion of welds where the weld toes are fused with TIG welding without filler wire. This ensures no lack of fusion or overlap presents at the weld toe thus increase the fatigue life of the welds.
Example of Autogenous Welding
Advance welding processes (AWP) for example electron beam welding, plasma welding, laser welding and mostly used as an autogenous technique to make weld joints.
Not all the welding processes can be used in an autogenous way as the welding electrode or filler wire is an essential part of the welding process. Such as SMAW welding is not possible without the welding electrode. The same applies to MIG/ MAG welding, Flux Cored Arc Welding (FCAW), Submerged arc welding (SAW), etc. as they always use consumable filler material and thus cannot be performed in an autogenous way.
Advantages of Autogenous welding
Autogenous welding offers a number of benefits compared to the other two fusion welding methods, mainly are:
- Good visual welds. Autogenous welding processes create more even weld compare to weld with filler.
- Improved fatigue properties: TIG refusion is usually carried out using Autogenous TIG on weld toes to increase the fatigue resistance of the welds.
- Reduced post weld griding job. Autogenous TIG require little grinding as not additional filler is added.
- Reduced material costs. The overall weld cost is low compare to weld with filler where filler wire cost is added to the weld cost.
- Easy to weld thin materials. This technique suits best of thin materials due to low heat input and easy control of the weld pudddle.
- Ease in automation. Using a special purpose machine (SPM) or other suitable means, autogenous welding can be easily automated.
Disadvantages of autogenous welding
- Not suitable for open root joints and other joint types excepts butt welds.
- Limited to thin materials joining usually up to 3 mm. Joining higher thickness will have risk of adequate penetration.
- Dissimilar welds due to dilution will produce change in the weld properties.
- Weld are weaker as they will have underfil issue becuase the weldd puddle is produced by melting the adjacent base material.
- Welds are prone to crack during solidification in material which lacks ductility..
- Not suitable when joining more than two parts or joint with more than two thickness for example cruciform joint.
- Welding is only possible for square butt joints.
- Weld need to be fully cleaned to produce sound joints.