Electrode Types E7018
Welding rod type:Low hydrogen carbon steel welding rod (iron powder low hydrogen type)
Implementation standards:AWS A5.1
Products Description
The E7018 electrode is a versatile and highly reliable iron-powder, low-hydrogen electrode with a basic, low-hydrogen coating (some models include iron powder for improved deposition efficiency). It is primarily used for welding carbon steel, low-alloy steel (such as 16Mn and Q345), shipbuilding steel, and pressure vessels, among other critical structures requiring high strength and crack resistance. As a key material for structural welding, its performance has been rigorously verified through testing: meeting AWS A5.1 standards, the deposited metal achieves a tensile strength of 70,000 psi (approximately 482.6 MPa), and weld fractures in all welds in the base metal during tensile testing, with an actual elongation of 27%, effectively safeguarding the mechanical integrity of the welded structure.
Practical Notes:
The E7018 electrode coating is highly hygroscopic and requires drying at 350-400°C for one hour before field use. Welding with undried electrodes in an environment with a humidity greater than 60% can easily lead to the formation of pores due to hydrogen-induced reactions. Therefore, special attention must be paid to storage and pretreatment procedures.
This electrode is suitable for all-position welding (horizontal, horizontal, vertical, and overhead welding), is compatible with AC and DC power sources, and uses a low-hydrogen coating design to reduce hydrogen diffusion and significantly reduce the risk of hydrogen-induced cracking. It is widely used in welding operations on heavy-load structures such as engineering machinery, bridges, and pressure vessels.
Core features and advantages
As a representative of low-hydrogen iron powder welding rods, the E7018 welding rod's core advantages are reflected in three dimensions: low-hydrogen crack resistance, excellent mechanical properties, and efficient welding process. Through the in-depth integration of measured data and engineering scenarios, it has become the preferred material for welding key structures such as bridges, pressure vessels, and heavy machinery.
Welding Tips:
When welding vertically, reduce the current by 10%: the recommended current for 3.2 mm electrodes is 90-110 A, and for 4.0 mm electrodes, 140-160 A. This is to avoid burn-through or undercutting of thin plates due to excessive current.
Low-hydrogen coatings require strict drying: dry at 350-400°C for 1-2 hours before use, then store in an insulated container at 80-100°C. Re-dry if exposed to air for more than 4 hours, as this can lead to porosity defects.
Technical Parameters
| item | Specific content | On-site commissioning suggestions |
|---|---|---|
| Product Model | E7018 | - |
| Welding rod type | Low hydrogen carbon steel welding rod (iron powder low hydrogen type) | - |
| Implementation standards | AWS A5.1 | - |
| Diameter specifications | 3/32 inch (2.4 mm), 1/8 inch (3.2 mm), 4.0 mm | For thin plate welding (≤6 mm), a 3.2 mm diameter is preferred to reduce the risk of burn-through. |
| Applicable current type | AC,DCEP | It is recommended to use DC reverse polarity, the arc stability is better than AC mode |
| Recommended welding materials | Medium carbon steel, low alloy structural steel, cold rolled steel | Before welding, the surface of the base material must be cleaned of oil and rust to avoid the formation of pores. |
| Welding position | All positions (flat & horizontal, vertical-up, overhead; vertical-down is not recommended) | When welding in the vertical-up position, it is recommended to reduce the current by 5%-10% to control the fluidity of the molten pool. |
| Chemical composition (deposited metal) | C≤0.12%,Mn≤0.9%,Si≤0.6%,Mo 0.4-0.65%,S≤0.035%,P≤0.035% | - |
| Mechanical properties | Tensile strength: ≥485 MPa (70,000 psi, measured 510 MPa); Yield strength: ≥400 MPa (measured 450 MPa); Elongation ≥30%; Impact energy: ≥34 J (-20°C, measured 42 J) | Welded joints must undergo a -20°C Charpy V-notch impact test to ensure low-temperature toughness meets standards. |
| Welding current range | 3.2 mm：120-150 A;4.0 mm：160-200 A | When welding plates below 6 mm, reduce the current by 10% and control the interlayer temperature below 250°C during multi-layer welding. |
| Coating moisture content | ≤0.6% (AWS A5.1 standard) | Before use, dry at 300-350℃ for 1-2 hours, store in a heat preservation tube at 80-120℃, and do not expose to air for more than 4 hours. |
| Diffusible hydrogen content | According to model suffix (e.g. E7018H4 is ≤4 ml/100g weld metal) | In humid environments, it is recommended to use low hydrogen type (H4/H8) suffix models to reduce the risk of cold cracking |
Key Considerations:
Before welding, remove rust, oil, and moisture from the base metal surface. Failure to do so can easily cause porosity.
When using a 3.2 mm diameter welding rod for thin plate splicing, the recommended welding speed is 15-20 cm/min to avoid burn-through.
For welding in low-temperature environments (<0°C), preheat the base metal to 80-150°C, and ensure that the interpass temperature does not drop below the preheat temperature.
| Welding Rod Diameter (mm) | Current Range (A) | Remarks |
|---|---|---|
| 2.5 | 60-90(AC/DC) | Avoid burn-through when welding thin plates. |
| 3.2 | 80-140(AC/DC) | Common specifications: 100-120A recommended. |
| 4.0 | 110-210(DC) | Preheating is required when welding thick plates. |
Special Environments and Precautions
Winter Construction Tips: When the ambient temperature is below 0°C, preheat the base metal to 80-100°C. The interpass temperature should not fall below the preheat temperature to prevent rapid cooling of the weld and cold cracking.
All-Position Welding Adaptability: Horizontal, horizontal, vertical (upward), and overhead welding are supported. However, for vertical and overhead welding, it is recommended to use electrodes with a diameter of ≤4.0mm and reduce the current by 10%. When striking the arc, use the backward-forward method to avoid striking the arc outside the groove. It is recommended to use an arc striker made of the same material as the base metal.
FAQ
Q: What are the main applications for E7018 welding rods?
A: They are used in welding structural steel, pressure vessels, pipelines, and shipbuilding. Due to their high weld strength and wide applicability, they are particularly suitable for welding critical components with stringent mechanical properties.
Q: How should I correctly use E7018 welding rods for welding?
A: First, clean the base metal surface. Use direct current positive polarity (DCEP) and maintain a short arc and a constant arc speed. The welding current should be adjusted according to the rod diameter (e.g., a 3.2 mm rod typically corresponds to 90-140 A).
Q: What causes arc instability during welding?
A: This may be due to improper current parameters (too high or too low), requiring recalibration of the welding current. Alternatively, the rod may be damp and should be dried as required (dry at 150-200°C for one hour).
Q: How can I resolve porosity in the weld?
Answer: The storage environment of welding rods must be strictly controlled (temperature 5 - 40℃, relative humidity ≤ 60%), and damp welding rods must be dried according to regulations; maintain short arc operation during welding to avoid air intrusion into the molten pool.
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