Questions You Should Know about electrode classification

13, Aug. 2024

 

8 Questions About Stick Welding Rods Answered

Whether you are a DIYer or a professional welder, one thing is certain: Stick welding requires a lot of skill. It also requires some know-how about stick electrodes (also called welding rods).

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Because variables such as storage techniques, electrode diameter and flux composition all contribute to stick rod selection and performance, arming yourself with some basic knowledge can help you minimize confusion and better ensure stick welding success.

1. What are the most common stick electrodes?

Hundreds, if not thousands, of stick electrodes exist. The most popular fall into the American Welding Society (AWS) A5.1 Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding. These include the E, E, E, E, E, E and E electrodes.

2. What do AWS stick electrode classifications mean?

To help identify stick electrodes, the AWS uses a standardized classification system. Classifications take the form of numbers and letters printed on the sides of stick electrodes. Each represents specific electrode properties.

For the mild steel electrodes mentioned above, here is how the AWS system works:
- The letter "E" indicates an electrode.
- The first two digits represent the resulting weld's minimum tensile strength, measured in pounds per square inch (psi). For example, the number 70 in a E electrode indicates that the electrode will produce a weld bead with a minimum tensile strength of 70,000 psi.
- The third digit represents the welding position(s) for which you can use the electrode. For example, 1 means operators can use the electrode in all positions and 2 means welders can use it on flat and horizontal fillet welds only.
- The fourth digit represents the coating type and the type of welding current (AC, DC or both) that can be used with the stick electrode.

3. What are the differences between E, E, E and E electrodes and when should I use them?

- E electrodes can only be used with direct current (DC) power sources. They deliver deep penetration and the ability to dig through rust, oil, paint and dirt. Many experienced pipe welders use these all-position electrodes for root welding passes on a pipe. However, E electrodes feature an extremely tight arc, which can make them difficult for novice welders to use.
- E stick electrodes can also be used for all-position welding using an alternating current (AC) welding power source. Like E electrodes, E electrodes produce a deep, penetrating arc that cuts through corroded or unclean metals. Many welders choose E electrodes for maintenance and repair work when a DC power source is unavailable.
- E electrodes work well in applications that require gap bridging between two joints. Many professional welders also choose E electrodes for high-speed, high-current fillet welds in the horizontal position. However, these electrodes tend to produce a shallower penetration profile and dense slag that will require additional post-weld cleaning.
- E electrodes produce a soft arc with minimal spatter, offer moderate penetration and have an easily-removable slag. You should only use these electrodes to weld clean, new sheet metal.

4. What are the differences between E, E and E electrodes and when should I use them?

- E electrodes produce about the same joint penetration as E electrodes and are designed for use on carbon and low-alloy steels. E electrodes contain a higher amount of iron powder, which increases deposition rate. You can also use them at higher amperages than E electrodes.
- E electrodes contain a thick flux with high powder content and are one of the easiest electrodes to use. These electrodes produce a smooth, quiet arc with minimal spatter and medium arc penetration. Many welders use E electrodes to weld thick metals such as structural steel. E electrodes also produce strong welds with high impact properties (even in cold weather) and can be used on carbon steel, high-carbon, low-alloy or high-strength steel base metals.
- E electrodes contain a high amount of iron powder that helps increase deposition rates. Many welders use E electrodes for high-speed horizontal or flat fillet welds. These electrodes perform well on steel plate that is at least 1/4-inch thick. Welders can also use them on metals that measure over 1/2-inch thick.

5. How do I choose a stick electrode?

First, select a stick electrode that matches the strength properties and composition of the base metal. For example, when working on mild steel, generally any E60 or E70 electrode will work.

Next, match the stick electrode type to the welding position and consider the available power source. Remember, you can use certain electrodes only with DC or AC, while you can use other electrodes with both DC and AC.

Assess the joint design and fit-up and select an electrode that will provide the best penetration characteristics (digging, medium or light). When working on a joint with tight fit-up or one that is not beveled, electrodes such as E or E will provide digging arcs to ensure sufficient penetration. For thin materials or joints with wide root openings, select an electrode with a light or soft arc such as an E.

To avoid weld cracking on thick, heavy material and/or complicated joint designs, select an electrode with maximum ductility. Also consider the service condition the component will encounter and the specifications it must meet. Will you use it in a low temperature, high temperature or shock-loading environment? For these applications, a low hydrogen E electrode works well.

Also consider the production efficiency. When welding in the flat position, stick electrodes with a high iron powder content, such as E or E, offer higher deposition rates.

For critical applications, always check the welding specification and procedures for the stick electrode type.

6. What function does the flux surrounding a stick electrode serve?

All stick electrodes consist of a rod surrounded by a coating called flux, which serves several important purposes. It is actually the flux, or the covering, that dictates where and how an electrode can be used.

When you strike an arc, the flux burns and produces a series of complex chemical reactions. As the flux ingredients burn in the welding arc, they release shielding gas to protect the molten weld pool from atmospheric impurities. When the weld pool cools, the flux forms slag to protect the weld metal from oxidation and prevent porosity in the weld bead.

Flux also contains ionizing elements that make the arc more stable (especially when welding with an AC power source), along with alloys that give the weld its ductility and tensile strength.

Some electrodes use flux with a higher concentration of iron powder to help increase deposition rates, while others contain added deoxidizers that act as cleaning agents and can penetrate corroded or dirty workpieces or mill scale.

7. When should I use a high deposition stick electrode?

High deposition rate electrodes can help complete a job faster, but these electrodes have limitations. The additional iron powder in these electrodes makes the weld pool much more fluid, meaning you can't use high deposition electrodes in out-of-position applications.

You also cannot use them for critical or code-required applications, such as pressure vessel or boiler fabrication, where weld beads are subject to high stresses.

High deposition stick electrodes are an excellent choice for non-critical applications, such as welding a simple liquid storage tank or two pieces of non-structural metal together.

8. What is the proper way to store and re-dry stick electrodes?

A heated, low humidity environment is the best storage environment for stick electrodes. For example, you need to store many mild steel, low hydrogen E electrodes at a temperature between 250- and 300-degrees Fahrenheit.

Generally, reconditioning temperatures for electrodes are higher than the storage temperature, which helps eliminate excess moisture. To recondition the low hydrogen E electrodes discussed above, the reconditioning environment ranges from 500 to 800 degrees F for one to two hours.

Some electrodes, like E, only need to be stored dry at room temperature, which is defined as humidity levels not exceeding 70 percent at a temperature between 40 and 120 degrees F.

For specific storage and reconditioning times and temperatures, always refer to the manufacturer's recommendations.

What You Need To Know About Welding Electrodes

If you are interested in a welding career, you might have already looked into the welding tools and equipment that are used. One of the most essential welding tools is the welding gun or welding machine which produces an electric current that melts and binds metal. Welding electrodes are essential, and it is important that a welder knows which type to use for different jobs.

What are welding electrodes?

An electrode is a coated metal wire. It is made of materials similar to the metal being welded. For starters, there are consumable and non-consumable electrodes. 1  In shield metal arc welding (SMAW) also known as stick, electrodes are consumable, which means that the electrode is consumed during its use and melts with the weld. In Tungsten Inert Gas welding (TIG) electrodes are non-consumable, so they don't melt and become part of the weld. With Gas Metal Arc Welding (GMAW) or MIG welding, electrodes are continuously fed wire. 2 Flux-cored arc welding requires a continuously fed consumable tubular electrode containing a flux.

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How to choose welding electrodes?

Choosing an electrode is determined by the requirements of the welding job. These include:

  • Tensile strength
  • Ductility
  • Corrosion resistance
  • Base metal
  • Weld position
  • Polarity
  • Current

There are light and heavy coated electrodes. Light coated electrodes have a light coating that is applied through brushing, spraying, dipping, washing, wiping, or tumbling. Heavy coated electrodes are coated by extrusion or dripping. There are three main kinds of heavy coatings: mineral, cellulose, or a combination of the two. Heavy coatings are used for welding cast iron, steels, and hard surfaces. 3

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What do the numbers and letters mean on welding rods?

The American Welding Society (AWS) has a numbering system that offers information about a specific electrode, such as what application it is best used for and how it should be operated for maximum efficacy.  (See table)

Digit Type of Coating Welding Current 0 High cellulose sodium DC+ 1 High cellulose potassium AC, DC+ or DC- 2 High titania sodium AC, DC- 3 High titania potassium AC, DC+ 4 Iron powder, titania AC, DC+ or DC- 5 Low hydrogen sodium DC+ 6 Low hydrogen potassium AC, DC+ 7 High iron oxide, potassium powder AC, DC+ or DC- 8 Low hydrogen potassium, iron powder AC, DC+ or DC-

The 'E' indicates an arc welding electrode. The first two digits of a 4-digit number and the first three digits of a 5-digit number stand for tensile strength. For example, E means 60,000 pounds per square inch (PSI) tensile strength and E means 100,000 psi tensile strength. The next to last digit indicates position. So, '1' stands for an all position electrode, '2' for a flat and horizontal electrode, and '4' for a flat, horizontal, vertical down and overhead electrode. The last two digits specify the type of coating and the welding current. 4

E 60 1 10 Electrode Tensile Strength Position Type of Coating & Current

As a professional welder, you must know the different types of electrodes and their applications in order to perform the welding job correctly. Considerations include welding method, welded materials, indoor/outdoor conditions, and welding positions. Practicing with various welding guns and electrodes can help you determine which electrode to use for what welding project.

Additional Sources

1 ' http://www.everlastgenerators.com/blog/differentiation-consumable-and-non-consumable-electrodes
2 ' http://weldguru.com/welding-electrode/
3 ' https://www.bakersgas.com/weldmyworld/welding-electrodes/
4 ' http://www.lincolnelectric.com/en-us/support/process-and-theory/Pages/aws-classifications-detail.aspx

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