SFA-5.9/SFA-5.9M: Specification for Bare Stainless Steel Welding Electrodes and Rods

This specification is similar to SFA-5.4 for covered electrodes except that it includes filler metal for use with GTAW, GMAW, PAW, and submerged arc welding (SAW) with flux. Filler metal classified in this specification is available as wire, strip, composite metal-cored and stranded-wire or rod. Weld metal deposited by these electrodes or rods has a minimum chromium content of 10 % and an iron content that is greater than that of any other element. Stainless steel filler metals see a wide range of uses for cryogenic-service, corrosion-resistant, and heat-resistant applications in the fabrication of ASME pressure vessels and piping.

Classification of these welding materials follows that of the SFA-5.4 stainless steel electrodes. The main difference is that the designation begins with the letters “ER” to denote solid wire or rods. SFA-5.9 also allows filler metals to have more than one classification, provided all the requirements are met for those classifications. For example, an ER308 filler metal may also be classified as ER308H. Mechanical properties are not included in the classification of filler metals in this specification; however, the tensile properties shown in SFA5.4 are generally applicable to the weld metal deposited by these filler metals.

Chemical composition is determined by analysis of the solid or product form except for composite and stranded electrodes, which are classified by analysis of the undiluted weld metal deposit. Both Sections IX and III [1] give additional requirements for the chemical analysis of filler metal and electrodes. QW-404.5 is an essential variable in Section IX for the welding procedure qualification; it details the chemical analysis requirements that are used to determine A-Numbers for ferrous metals. Section III, NB-2432 contains the requirements for chemical analysis of welding materials to be used for the fabrication and repair of Class 1 nuclear components or vessels.

Stainless steel filler metals in this specification fall within A- Nos. 6–9 composition ranges in QW-442 of Section IX. All bare wires, composite wires, or strips in this specification are grouped as F-No. 6 in QW-432

As with all stainless steel materials, ferrite is important in reducing the tendency for hot-cracking and for strengthening the final weld deposit. Although ferrite is not present in all classifications in this specification, it is beneficial when highly restrained joints or heavy sections are welded. Some variations of ferrite in the deposit can be expected when the same filler metal is used with different welding processes.

Ferrite determination is not required to classify filler metal or electrodes in this specification. However, the purchaser may impose ferrite controls when ordering filler metal to ensure sound welds for the selected welding process or procedure. As explained in the discussion of SFA-5.4, ferrite can be determined by chemical analysis of the undiluted weld deposit or be measured with various magnetic instruments. 

Because the chemical composition of the solid or product form is required to classify materials in this specification, ferrite is commonly determined by chemical analysis.

This specification includes welding materials for use on a wide range of stainless steel base metals. The following paragraphs briefly discuss some different types of stainless steel filler metals.

Nitrogen-Strengthened, Austenitic Stainless Steel Electrodes and Rods

The ER209, ER218, ER219, and ER240 filler metals are intended for welding nitrogen-strengthened, austenitic stainless steels that 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, ER209 can be 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. ER218 is designed for welding type UNS S21800 that is listed in ASME Material Specifications SA-240 and SA-479. ER219 is typically used for welding UNS S21900. ER240 can be 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. Nitrogen strengthened, austenitic stainless steels are grouped as P-No. 8, Group 3 in QW/QB-422 of Section IX.

 Austenitic Stainless Steel Electrodes and Rods

The ER308-grouped filler metals have wide use in the welding of Types 304 stainless steels, which are grouped as P-No. 8 in QW/QB-422 in Section IX, P-No.8 base metals 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, SA-479, SA-666, SA-688, SA-813, and SA-814. Type 304 (UNS S30400) or Type 304L (UNS S30403) are the most common stainless steels welded with either ER308 or ER308L. The “L” grades are generally selected for improved corrosion resistance because the 0.03% maximum carbon content of weld metal deposited by ER308L reduces the possibility of intergranular carbide precipitation. Because of the chemistry overlap, an ER308 could also be certified as ER308H.

The ER309 series of filler metals contains more chromium and nickel than the ER308 types. These filler metals 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 ER309 and ER309L are commonly used for applying the first layer of corrosion-resistant stainless-steel overly. The remaining layers are typically deposited with ER308 or ER308L. Because of their richer chemical composition, electrodes in this group are also good for joining dissimilar metals, such as Type 304 stainless steel joined to carbon or low-alloy steel.

Filler metals in the ER316 grouping 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 are typically listed in the same ASME Material Specifications as UNS S30400.

The ER347 filler metals are stabilized with columbium or columbium plus tantalum to reduce the possibility of intergranular chromium carbide precipitation for increased intergranular corrosion resistance. These filler metals are usually used for welding stainless steels of similar composition that have been 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 of Section IX and are listed in the same ASME Material Specifications as UNS S30400.

The ER308, ER309, ER316, and ER347 grouping of filler metals in this specification also have grades that contain silicon improve the usability of these electrodes with GMAW. The classifications with silicon end with the elemental symbol “Si.”

The ER3556 weld deposits are resistant to high-temperature corrosive environments containing sulfur. This filler metal is typically used to join UNS R30556 in ASME Material Specifications SB-435, SB-572, SB-619, SB-622, and SB-626. These base metals are grouped as P-No. 45 in the nonferrous QW/QB-422 P-number tables of Section IX

Martensitic Stainless Steel Electrodes and Rods

The ER410 filler metals deposit a martensitic, 12% chromium (12Cr) alloy weld. Preheat and post weld heat treatments are generally recommended. These electrodes could be used to weld UNS S41000 or S41008, listed in ASME Material Specifications SA240, 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 and Rods

The ER430 filler metals usually require both preheat and post weld heat treatment to obtain optimum mechanical properties and corrosion resistance. P-No. 7 base metals, Types 405 (UNS S40500) and 430 (UNS S43000) listed in ASME Material Specifications SA-240, SA-268, and SA-479, can be welded with these filler metals.

Duplex Stainless Steel Electrodes and Rods

The ER2209, ER2553 and ER 2594 filler metals deposit duplex stainless steel weld metal having an austenitic-ferritic (duplex) microstructure. ER2209 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 is primarily used to weld duplex stainless steels containing approximately 25% chromium. ER2594 is used to weld super duplex stainless steels with a PREN of at least 40.