Flux-Cored Electrode Usability Designators: What Do They Mean?
Those dash numbers refer to the usability of the electrode with requirements for polarity and general operating characteristics. Here’s how they work.
Posted: June 28, 2013
Table 3 lists the tests required for classification. Table 6 lists the weld metal chemical composition requirements. In addition, Annex A, Section A7 contains a detailed description and intended use for each usability designator. A summary of the main points of each usability designation group are included in this article in Figures 2 and 3.
Addressing the second question for this column, some electrodes do indeed carry two or more different AWS classification numbers. This is quite common with electrodes that are dual classified as a “T-1” and “T-9” electrode.
Referring back to Figure 3, note that these two usability designations have the exact same electrode and operating characteristics.
The only difference is with the impact properties. A “9” electrode has a more stringent impact toughness requirement of 20 ft-lbf @ -20 deg F (27 J @ -29 deg C) versus a “1” electrode of 20 ft-lbf @ 0 deg F (27 J @ -18 deg C).
Therefore, if a specific electrode can meet the minimum impact toughness requirement at the colder -20 deg F (-29 deg C) temperature, then it can also more easily meet it at the warmer 0 deg F (-18 deg C) temperature. Thus one electrode can meet the requirements of two different usability classifications.
In other cases, electrodes may be tri-classified as a “T-1”, “T-9” and “T-12” electrode. A “12” designation classification also has the exact same electrode and operating characteristics as a “1” and “9” classification. A “12” classification has a slightly lower maximum manganese (Mn) level and slightly lower maximum tensile strength cap than “1” and “9” classifications.
Therefore, “12” electrodes also meet the requirements of “1” and “9” electrodes. While “12” electrodes traditionally were classified by themselves, manufacturers have more recently begun to tri-classify them.
Note that flux-cored electrodes also can have an optional “J” designator. This means that the electrode can meet an even more stringent impact toughness requirement of 20 ft-lbf @ -40 deg F (27 J @ -40 deg C). Most “12” electrodes have the optional J designation.
However, a “12” electrode does not technically have to meet Charpy V-notch (CVN) values of 20 ft-lbf @ -40 deg F (27 J @ -40 deg C), it is just that most do. Note also that while most “1” / “9” electrodes do not have an optional J designator, they technically could have it if they met the impact requirement. And, in fact, some do carry the optional J designator, such as our own Outershield® 71M electrode.
This column has focused on carbon steel electrodes, but there are also low-alloy, flux-cored electrodes available in the welding market. These electrodes are classified in the AWS document A5.29:A5.29M:2010 “Specification for Low Alloy Electrodes for Flux Cored Arc Welding”. These electrodes produce welds that are typically stronger than welds made with carbon steel electrodes, and have minimum tensile strengths of 80 to 120 ksi (550 – 827 MPa).
Their electrode classification numbers are similar to carbon steel electrodes, including similar (but less) usability designation classifications. The mechanical properties and weld metal chemical composition requirements of each usability classification can vary with different alloy types and alloy levels in each electrode. Again, the detailed requirements of each usability classification are contained in various tables in the A5.29:A5.29M filler metal specification.
These usability designators for low alloy flux cored electrodes can by sub-divided into the two main categories of electrodes as follows.
- Self-Shielded, Flux-Cored Electrodes: T4, 6, 7, 8, G
- Gas-Shielded, Flux-Cored Electrodes: T1, 5, G
One slight difference with low alloy electrodes’ classification numbering system is that the usability designator, following the “T” designator, now precedes the dash, with the deposition composition or alloy designator now following the dash.
For example, a carbon steel electrode might have the classification number “E71T-1M-JH8,” while a low alloy electrode might have the classification number “E81T1-K2M-JH4”.
As a final point, note that there is a new filler metal specification, AWS A5.36/A5.36M:2012, “Specification for Carbon and Low-Alloy Steel Flux Cored Electrodes for Flux Cored Arc Welding and Metal Cored Electrodes for Gas Metal Arc Welding.” This specification covers both carbon steel and low alloy flux-cored electrodes, as well as carbon steel and low alloy metal cored electrodes.
It is also the first of a new and improved style of filler metal specifications. This specification is effective now and runs in conjunction with AWS A5.20 and A5.29 until 2015. At that point the old specifications will be obsolete and the new A5.36 specification will be the only one in effect.
While the usability designations are similar to those in A5.20 and A5.29, it does include a few slight changes and some additional ones involving metal-cored wires. However, discussion of this new A5.36 specification is for a future column.
* The dual numbering system for filler metal specifications (e.g. A5:20/A5:20M) means that they include both English units and metric units. The year of publication is also included at the end of the document number.
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