How to Choose the right Welding Rods
Welding is a skill which takes a lot of time to master for one to be good in the art and more challenging is to choose the correct welding electrode that fits the job. These stick electrodes can be found in so many varieties, and each of these has the ability to provide different mechanical properties and works under a specified power source. Therefore, the following are should be considered when selecting the correct stick electrode:
1. The base metal type
2. The joint fit –up
3. Welding positions
Before starting any welding practice, consider the following basic guidelines as far as stick electrode is concern:
- Access of the base metal
The most important step to be considered before choosing a en electrode is to determine the composition of base metal. Here, the major aim is to match or nearly match the composition of the electrode with the base metal type which will ensure strong weld formed. The following questions can assist in determining the composition of the base metal:
a. What’s the physical appearance of the base metal?
If the component is broken, check for its coarse and also the grain internal structure, and this eventually signifies its cast metal.
b. Does the metal possess any magnetic properties?
If in any case the metal is magnetic, then the chances are the base metal you are working on is carbon steel or alloy steel. On the other hand if it is non magnetic, the base metal could be manganese steel, stainless steel or non-ferrous alloys such as aluminum, copper or titanium.
c. What type of sparks does the base metal gives off when in touch with a grinder?
As a common rule of thumb, the presence of more flare indicates high carbon content.
- Welding current
Each welding electrode has a specified type of current to be used i.e. some can only be used with D.C or A.C current or even both. Ensure you have the correct reference point on the type of welding for specific electrode e.g. refers AWS classification. The welding current affects the penetration profile of the weld that will be formed.
- The base metal thickness, shape and joint fit –up
Normally, thick base metals require electrodes with high ductility and low hydrogen to prevent surface cracking.
For thin metals, electrodes that give soft arc should be used. Also, the electrodes with minimum diameter will give shallow penetration will help prevent burn-through on thin metals. The joint design and fit- up should assessed , so that if the joint has a very tight fit –up, then an electrode with digging arc should be used. For base metal with wide root openings, choose an electrode that provides a concave weld face which is suitable for making welded grooves and bridge gaps.
- Welding positions
As a rule of thumb, each electrode has a specific welding position that’s best fit.
Service and specification conditions of the weld
It is advisable to check for the conditions on which the welded part will encounter during it service e.g. if it will be used in low or high heat environment, or subjected to repetitive shock on the weld. Also, check out for welding specifications especially if working on critical applications such has boiler fabrication.
- Environmental conditions of the metal to be welded.
To achieve the best results, remove the excessive mill scale, moisture, grease and rust on the base metal as this will help increase travel speed and prevent porosity.
Miller, one of the most respected brands has a very useful tool that can really help when choosing the right welding rod.
One most simple choose: What material are you welding? and What electrode are you using?
and the calculator indicates the best settings of: Suggested Amperage Range and the optimal welding parameters of:
Penetration, Position of Weld and usage
Conclusion
Putting under consideration all the above factors will assist in guiding to select the correct stick electrode for a specific application. Since there are a wide range of welding electrodes, there could be many solutions for one application. More detail information can also be obtained from any local supplier of welding equipment.
Images in this post are from Miller . Please visit them and check their excellent products.
