SMAW electrodes specifications

SMAW electrodes (Shielded Metal Arc Welding) are consumable flux-coated rods that, when melted, generate an electric arc to join metals. Their AWS classification (e.g., E6010, E7018) defines mechanical properties, current type, welding position, and coating composition. They are the basis of manual welding and are selected based on base material, position, and strength requirements.

Technical specifications of common electrodes

E6010, E6013, E7018, and E308L electrodes show significant differences in tensile strength, flux type, and applicability. Table 1 summarizes their main properties according to AWS A5.1/A5.4 standard.

Electrode	Tensile strength (MPa / ksi)	Yield strength (MPa / ksi)	Elongation (%)	Coating type	Current and polarity
E6010	414 MPa / 60 ksi	331 MPa / 48 ksi	22% min.	Sodium cellulosic	DC+ (electrode positive)
E6013	414 MPa / 60 ksi	345 MPa / 50 ksi	17% min.	Potassium rutile	AC or DC±
E7018	482 MPa / 70 ksi	393 MPa / 57 ksi	22% min.	Low hydrogen, iron powder	AC or DC+
E308L	517 MPa / 75 ksi	414 MPa / 60 ksi	35% min.	Low carbon, limestone-rutile	DC+ (preferred)

Operating parameters by material and diameter

Each electrode operates in amperage ranges defined by its diameter and composition. Table 2 shows the recommended parameters for carbon and stainless steels in flat position.

Electrode	Diameter (mm / in)	Amperage (A)	Arc voltage (V)	Deposition rate (kg/h / lb/h)	Slag thickness (mm / in)
E6010	2,5 mm / 3/32 in	50–80 A	22–28 V	0,9 kg/h / 2,0 lb/h	0,8 mm / 0.03 in
E6010	3,2 mm / 1/8 in	70–130 A	24–30 V	1,2 kg/h / 2,6 lb/h	0,8 mm / 0.03 in
E6013	2,5 mm / 3/32 in	60–100 A	20–26 V	1,1 kg/h / 2,4 lb/h	1,2 mm / 0.05 in
E6013	3,2 mm / 1/8 in	90–150 A	22–28 V	1,4 kg/h / 3,1 lb/h	1,2 mm / 0.05 in
E7018	2,5 mm / 3/32 in	70–110 A	22–28 V	1,0 kg/h / 2,2 lb/h	2,0 mm / 0.08 in
E7018	3,2 mm / 1/8 in	100–160 A	24–30 V	1,5 kg/h / 3,3 lb/h	2,0 mm / 0.08 in
E308L	2,5 mm / 3/32 in	55–85 A	22–28 V	0,8 kg/h / 1,8 lb/h	1,5 mm / 0.06 in
E308L	3,2 mm / 1/8 in	80–140 A	24–30 V	1,1 kg/h / 2,4 lb/h	1,5 mm / 0.06 in

Dimensional and operational tolerances

Standard electrode diameters range from 1,6 mm to 5,0 mm / 1/16 in to 3/16 in with a tolerance of ±0,05 mm / ±0.002 in on the metal core. Typical length is 350 mm / 13.8 in with a tolerance of ±5 mm / ±0.2 in. Coating concentricity must maintain a maximum thickness difference of 0,1 mm / 0.004 in. Diffusible hydrogen content in E7018 must not exceed 8 ml/100g in newly opened electrodes and 4 ml/100g in critical applications. Coating moisture for E7018 is kept below 0,4% by weight before use.

Applicable materials

SMAW electrodes are used on carbon steels, low-alloy steels, austenitic stainless steels, iron castings, and nickel alloys. Specific materials and compatible electrodes include ASTM A36 (E6010, E7018), AISI 1045 steels (E6013, E7018), 304L stainless steels (E308L), API 5L X42–X70 pipe steels (E6010 for root pass, E7018 for fill), and AISI 316 steels (E316L). Not recommended for aluminum or titanium with standard electrode; copper requires special electrode with preheating.

Advantages and limitations of the SMAW process by electrode

The choice of electrode conditions the operational advantages and limitations of the process. Table 3 summarizes this comparison.

Electrode	Key advantages	Main limitations
E6010	Deep penetration, fast solidification	Only DC, heavy spatter
E6013	Smooth arc, easy striking, low spatter	Heavy slag, low penetration
E7018	Low H₂ content, high toughness	Requires holding oven
E308L	Corrosion resistance, low carbon	Only for 18Cr-8Ni stainless steels

Selection guide by application

For root pass in pipes with complete penetration, E6010 1/8 in (3,2 mm) at 70–130 A is recommended, followed by E7018 for fill at 100–160 A. For structural shop welding on A36 steel, E7018 3/32 in (2,5 mm) at 70–110 A is selected. For thin sheet repairs, E6013 2,5 mm / 3/32 in at 60–100 A is preferred. For welding 304L stainless steel exposed to corrosive media, E308L with DC+ current between 55 and 140 A depending on diameter is used. For joining galvanized steel, E6013 with low voltage of 20–22 V is recommended to minimize zinc porosity.

Storage and handling recommendations

Cellulosic electrodes (E6010) are kept in sealed packaging at room temperature between 10 °C and 30 °C / 50 °F and 86 °F and relative humidity below 60%. Low hydrogen E7018 electrodes are stored in an oven at 120 °C / 250 °F and used within 4 hours after removal. E308L and other stainless steel electrodes are kept in a dry place at 20–25 °C / 68–77 °F and dried at 150 °C / 300 °F for 1 hour before use if they have absorbed moisture. Inadequate storage conditions cause hydrogen cracking, porosity, and excessive spatter.

Formula for heat input (Heat Input)

Q = (V × I × 60) / (S × 1000)

Symbol	Variable	Unit
Q	Heat input	kJ/mm
V	Welding voltage	V
I	Welding current	A
S	Travel speed	mm/min

The factor 1000 converts J/mm to kJ/mm. For E6010 with V=26, I=110, S=200 mm/min, Q=0.86 kJ/mm. For E7018 with V=28, I=140, S=250 mm/min, Q=0.94 kJ/mm. An excessive Q (>2.0 kJ/mm) in carbon steels weakens the heat-affected zone; an insufficient Q (<0.5 kJ/mm) produces lack of fusion.

Physical process details of the coating

The flux coating the electrode decomposes during the arc forming three essential components in approximate volumetric proportions of 10%–15% liquid slag, 25%–35% shielding gases, and 40%–55% metallic allotropes incorporated into the weld pool. The slag solidifies at temperatures between 1100 °C and 1200 °C / 2012 °F and 2192 °F, insulating the bead from the atmosphere. The gases generated by cellulose in E6010 produce a reducing atmosphere with predominance of H₂ and CO, while the basic coating of E7018 mainly releases CO₂ and CO, reducing diffusible hydrogen. The slag of E6013 contains TiO₂ around 12% by weight, which gives it fluidity and easy removal at low temperature (<400 °C / 752 °F).

Frequently Asked Questions (FAQ)

What is the fundamental difference between E6010 and E6013?

The difference lies in 2 aspects: E6010 has a cellulosic coating that generates up to 30% deeper penetration than E6013, but only operates with DC+ current, while E6013 uses a rutile coating compatible with AC/DC± and produces a smoother arc with lower penetration.

Why do E7018 electrodes require a storage oven?

Because their diffusible hydrogen content must remain below 8 ml/100g. At room temperature without protection, absorbed moisture can generate more than 15 ml/100g of hydrogen in just 2 hours, causing cold cracking.

Can E308L be used on carbon steel?

Not recommended because the dilution of carbon from the base steel into the stainless steel weld bead forms chromium carbides, reducing corrosion resistance by more than 50% and may cause hot cracking.

How does electrode diameter affect deposition rate?

In E7018, when increasing diameter from 2,5 mm / 3/32 in to 3,2 mm / 1/8 in, the deposition rate increases from 1,0 kg/h / 2,2 lb/h to 1,5 kg/h / 3,3 lb/h, an increase close to 50%.

What is the maximum amperage for E6010 on pipe?

On pipe with thickness 6 mm / 0.24 in, the maximum amperage for root pass with E6010 3,2 mm / 1/8 in is 130 A, because exceeding that value produces burn-through and burning of the joint with a failure probability above 25%.

Which electrode to use for welding gray cast iron without cracking?

A pure nickel-based electrode (AWS ENi-CI) is used with preheating to 300 °C / 572 °F and slow cooling; E6010, E6013, or E7018 electrodes are not suitable because they form brittle martensite.

Sources Consulted

• engineeringtoolbox.com: https://www.engineeringtoolbox.com/corrosion-protection-pipes-d_564.html
• efunda.com: https://www.efunda.com/processes/metal_processing/welding_table.cfm?search_string=n%20t%20c
• manufacturingguide.com: https://www.manufacturingguide.com/en/metal-powder-welding