SFA-5.4/SFA-5.4M: Specification for Stainless Steel Electrodes for SMAW

Covered electrodes manufactured to this specification are used for depositing stainless steel weld metal with the SMAW process. Weld metal deposited by these electrodes has chromium content of 10.5% or greater and an iron content that is greater than that of any other element. Stainless steel electrodes have a wide range of uses for corrosion resistance, cryogenic service, and heat- resistant applications in the fabrication of ASME pressure vessels and piping.

Unlike the carbon steel electrodes of SFA-5.1, stainless steel classifications represent the chemical composition rather than the tensile properties. The last two numbers define positional usability and electrical characteristics. Therefore, an E308L-16 electrode is defined by the letter “E” for electrode, the “308L” for the chemical composition (nominal 19% Cr and 10% Ni with low carbon content). The last two number designators, “–16,” indicate all position usability with ac or dc electrode positive (DCEP). Another common stainless steel electrode classification

This specification allows an electrode to be classified under more than one classification if all requirements are met for those classifications. However, electrodes may not be classified under more than one of the following designations: EXXX-15, EXXX-16, EXXX-17, EXXX-25, or EXXX-26. For example, an E308-16 electrode may also be dual-classified as an E308H-16 electrode, but it cannot be classified as E308-15.

A stainless steel electrode is composed of a core wire and a flux covering that determines the usability classification of the electrode. It should be noted that the core wire does not necessarily contain all the elements that determine the weld deposit composition. Depending on the type of electrode, the covering can contribute some or most of the alloying elements.

The composition ranges of weld metal deposited by stainless-steel electrodes are grouped as A-No. 6–9 in QW-442 of Section IX Stainless-steel electrodes are grouped as F-Nos. 1, 4, and 5 in QW432 of Section IX. Table 3.4.1 has a listing of each electrode classification and the corresponding F-Number and A-Number.

Although the amount of ferrite in the weld deposit is not a factor for classification, it is an important characteristic in stainless steel welding. Stainless steel welds are more susceptible to cracking or fissuring during welding than welds made with carbon steel electrodes. Ferrite in the deposit helps to reduce this tendency for hot-cracking and strengthens the final weld. In some corrosion resistant applications, electrodes are used that deposit welds with little or no ferrite because ferrite may have a detrimental effect. Electrodes classified as E310, E320, E320LR, E330, E383, and E385 deposit fully austenitic (i.e., no ferrite) weld metal. Ferrite is also known to reduce toughness in cryogenic service and to transform into the brittle sigma phase in high-temperature service. Austenitic weld deposits that are high in ferrite can also transform to the sigma phase during post weld heat treatments.

It is not uncommon to specify ferrite ranges to avoid problems associated with too little or too much ferrite, depending on the application. Ferrite can be determined by chemical analysis of the undiluted weld deposit or be measured with various magnetic instruments. The term ferrite number (FN) was selected by the Welding Research Council (WRC) to be used in lieu of percent ferrite for the magnetic-measuring instruments. The purpose of the ferrite number

3.4.2 SFA-5.4: TYPICAL SMAW STAINLESS STEEL ELECTRODE CLASSIFICATION

E – 308L -15

E – Electrode

308L – Chemical Composition

15 – Current and Position

Nitrogen-Strengthened, Austenitic Stainless Steel Electrodes

The E209, E219, and E240 electrodes are intended for welding nitrogen-strengthened, austenitic stainless steel base metals having comparable compositions. These types of stainless steels exhibit high strength and toughness over a wide range of temperatures. Nitrogen alloying also reduces the tendency for intergranular carbide precipitation in the weld area, thereby increasing its resistance to intergranular corrosion. Typically, E209 is used for welding type XM-19 (UNS S20910), which is listed in ASME Material Specifications SA-182, SA-240, SA-249, SA-312, SA-358, SA-403, SA-479, SA-813, and SA-814. E219 is designed for welding type UNS S21900 base metal. E240 is typically used for welding type XM-29 (UNS S24000), which is listed in ASME Material Specifications SA-240, SA-249, SA-312, SA-358, SA-479, SA-688, SA-813, and SA-814. Additionally, these electrodes are used for welding dissimilar alloys of carbon steel and stainless steel, and also for corrosion-resistant overlay. E240 can be used in cladding or overlay applications for wear resistance as well.

Austenitic Stainless Steel Electrodes

The E308 series of electrodes typically have wide ASME Code usage in the welding of Type 304 stainless steels listed as P-No. 8 in QW/QB-422 of Section IX Type 304 (UNS S30400) or type 304L (UNS S30403) are the most common stainless steels welded with either E308 or E308L. Most of the 304 stainless steels are listed in ASME Material Specifications SA-182, SA-213, SA-240, SA-249, SA-312, SA-336, SA-358, SA-376, SA-403, SA-409, SA-430, SA479, SA-666, SA-688, SA-813, and S A-814. The “L” grades are generally selected for improved corrosion resistance because the 0.04% maximum carbon content of weld metal deposited by E308L reduces the possibility of intergranular carbide precipitation.

The E309 series of electrodes contains more chromium and nickel than the E308-type electrodes. These electrodes are used to weld base metals such as UNS S30900, S30908, S30909, S30940, and S30941. Base metals of these compositions are generally listed in the same ASME Material Specifications as UNS S30400.

Both E309 and E309L are commonly used for the first layer when a corrosion resistant stainless steel overlay is applied. The remaining layers are typically deposited with E308 or E308L. Because of their richer chemical composition, electrodes in this group are also good for joining dissimilar metals, such as joining Type 304 stainless steel to carbon or low-alloy steel.

Electrodes in the E316 series are generally used for welding base metals of like designations (316, 316L, etc.). Molybdenum strengthens these stainless steels and provides creep resistance at elevated temperatures. Type 316 base metals appear in most of the same ASME Material Specifications as UNS S30400.

The E347 stainless steel electrodes have columbium or columbium plus tantalum to reduce the possibility of intergranular chromium carbide precipitation for increased intergranular corrosion resistance. These electrodes are usually used for welding stainless steels stabilized with columbium or titanium, such as Type 347 (UNS S34700). Type 347 stainless steels are grouped as P-No. 8 in QW/QB-422 in Section IX and are located in the same ASME Material Specifications as UNS S30400.

Austenitic Manganese Steel Electrodes

Type E307 electrodes are used primarily for moderate strength welds with good crack resistance between dissimilar steels such as austenitic manganese steel and carbon steel forgings or castings.

Martensitic Stainless Steel Electrodes

The E410 electrodes produce a martensitic, nominal 12% chromium (12Cr) alloy deposit. Both preheat and post weld heat treatments are generally recommended. These electrodes can be used to weld UNS S41000 or S41008, listed in ASME Material Specifications SA-240, SA-268, and SA-479. E410NiMo is typically used for welding castings such as Type CA6NM, listed in ASME Material Specification SA-487.

Ferritic Stainless Steel Electrodes

The E409Nb and E430 electrodes usually require both preheat and post weld heat treatments to obtain optimum mechanical properties and corrosion resistance. P-No. 7 base metal Types 405 (UNS S40500) 409 (UNS S40900) and 430 (UNS S43000), listed in ASME Material Specifications SA-240, SA- 268, and SA-479, can be welded with these filler metals.

Precipitation-Hardening Stainless Steel Electrodes

The E630 electrodes are designed for welding Type 630 (UNS S17400) precipitation-hardening stainless steel and similar steel. The final weldment may be used as-welded or welded and precipitation hardened, or welded, solution treated, and precipitation-hardened (depending on the application). Precipitation-hardening stainless steel materials are not listed in QW/QB-422 of Section IX.

Duplex Stainless Steel Electrodes

Type E2209, E2553 E2593, E2594, and E2595 are duplex stainless steel electrodes. Weld metal deposited by these electrodes has an austenitic-ferritic (duplex) microstructure. E2209 is used primarily to weld duplex stainless steels such as UNS S31803, listed in ASME Material Specification SA-240. UNS S31803 is grouped as P-No. 10H, Group 1 in QW/QB-422 of Section IX. E2553 and E2593 are used primarily to weld duplex stainless steels containing approximately 25% chromium. E2594 and E2595 are used to weld the super-duplex stainless steels with a pitting resistance equivalent number (PREN) of at least 40.