E7018-H4R Low Hydrogen Welding Electrode

I. Product Introduction

The E7018-H4R is a low-hydrogen, all-position, high-strength welding electrode designed for welding medium- and high-strength mild steel/low-alloy steel structures. It is particularly suitable for thick plates and high-constraint applications. With advantages such as low hydrogen crack resistance, stable performance, all-position adaptability, and moisture resistance for easy storage, it is widely used in fields like bridges, pressure vessels, and machinery manufacturing that have strict requirements for welding safety and structural stability, achieving a balance between safety and construction convenience.

II. Core Features and Advantages

1. Low Hydrogen Crack Resistance, Outstanding Safety Performance

• Adopts a low-hydrogen coating (the "8" in the model indicates low-hydrogen type), with a hydrogen content reaching H4 level (≤4mL/100g), which can minimize hydrogen accumulation during welding.
• Effectively prevents "cold cracking" (cracks formed by the combined action of hydrogen and restraint stress during the cooling stage after welding), making it suitable for safety-critical structures such as pressure vessels and bridges.

2. Stable Weld Performance, Balancing Strength and Toughness

• The weld metal strength is ≥483MPa, and the room-temperature impact energy is ≥27J, meeting the strength requirements of low-carbon and low-alloy steels such as Q235 and Q345.
• While ensuring the load-bearing capacity of the structure, it maintains excellent toughness, avoiding the risk of fracture caused by material embrittlement, and is suitable for most industrial structural welding scenarios.

3. All-Position Welding, Improving Construction Efficiency

• The "1" in the model represents all-position adaptability, enabling welding in any position including flat, vertical, horizontal, and overhead welding.
• There is no need to replace electrodes due to structural limitations, greatly improving construction flexibility, especially suitable for welding complex components such as heavy machinery frames and high-rise building steel structures.

4. Moisture-Resistant Design, Reducing Storage Costs

• Marked with "R" (moisture-resistant feature), unopened electrodes can be stored for a long time in a dry room-temperature environment without the need for sealed refrigeration (different from ordinary low-hydrogen electrodes).
• After opening, the electrodes need to be dried at 350-400°C for 1-2 hours and then stored in an insulated container at 80-100°C to prevent moisture absorption and pore formation, effectively reducing storage and drying costs.

III. Comparison with Similar Welding Electrodes

IV. Precautions for Use

1. Power Supply Requirements

• DC reverse polarity (DCEN) must be used; AC power supply is strictly prohibited.
• Reason: Low-hydrogen (alkaline) coatings have poor electrical conductivity, and AC power supply is prone to causing arc instability (arc breakage, excessive spatter). DC reverse polarity can ensure a stable arc and reduce defects such as porosity and incomplete penetration.

2. Drying and Storage

3. Preheating and Postheating

• Preheating: When welding thick plates (≥25mm) or rigid structures, preheating to 80-150°C is required (adjust according to the carbon equivalent of the steel).
• Postheating: If necessary, post-heating at 250-350°C is required after welding to accelerate hydrogen diffusion and further reduce the risk of cracking.

4. Welding Environment

• Avoid welding in environments with humidity >80% or wind speed >8m/s (prone to pore formation).
• For outdoor construction, windproof and moisture-proof facilities should be set up to ensure a stable welding environment.

V. Product Specifications (Diameter × Length / Current Range)

VI. Transportation and Storage Details

1. Transportation Protection

• Packaging: Moisture-proof cartons + pallets are used, and anti-slip mats are placed at the bottom of the pallets to prevent stacking from tilting.
• Moisture Protection: For long-distance transportation (especially in humid areas), waterproof tarpaulins should be covered to prevent rainwater and condensation from seeping in.
• Loading and Unloading: Handle with care, prohibit dropping and collision to prevent electrode coating detachment and inner box damage.

2. Storage Requirements

• Ideal Environment: Temperature 10-30°C, relative humidity ≤50%, well-ventilated and dry, away from water sources, steam pipes, and corrosive substances.
• Stacking Specifications: Pallets should not be stacked more than 3 layers high. The bottom pallet should be elevated by more than 10cm using wooden supports to isolate from ground moisture.
• Shelf Life: Unopened products have a shelf life of 2 years under standard conditions; after opening, if strictly following the drying process, they can be used within 1 year (the opening date must be recorded).

VII. Core Application Fields

1. Large-Scale Steel Structures: Bridge load-bearing structures, high-rise building steel frames, crane booms, etc. These structures withstand high loads and alternating stresses, and the low-hydrogen feature prevents cracks.
2. Pressure Vessels and Pipelines: Chemical reactors, oil and gas pipelines, boiler cylinders, etc. The low-hydrogen coating reduces the risk of hydrogen-induced cracking and ensures sealing and pressure resistance.
3. Heavy Machinery: Heavy machinery frames, machine tool beds, structural components of excavators/loaders. All-position welding adapts to complex structures, balancing strength and toughness.
4. Energy Equipment: Wind turbine towers, power plant steel structure supports, etc. The moisture-resistant design reduces defects caused by improper storage, suitable for long-term outdoor use.

VIII. Frequently Asked Questions (FAQ)

Q1: Why can't AC power be used for E7018-H4R?

A1: Low-hydrogen coatings have poor electrical conductivity, and AC power supply is prone to causing arc instability (arc breakage, excessive spatter). DC reverse polarity can provide a stable arc, ensuring full fusion of the weld pool and reducing defects.

Q2: Will multiple drying cycles affect the electrode performance?

A2: A maximum of 3 drying cycles (350°C/1 hour) is allowed. Exceeding this limit will cause burnout of alloying elements in the coating and reduce the adhesion between the coating and the core, leading to coating detachment and porosity. It is recommended to stop using the electrodes after more than 3 drying cycles.

Q3: Can it be mixed with acidic electrodes like E6013 to weld the same structure?

A3: Not recommended. E6013 has high hydrogen content (prone to cracking), and its tensile strength (about 414MPa) is lower than that of E7018-H4R (483MPa). Mixing will result in uneven joint strength and increase the risk of cracking.

Q4: What causes porosity on the weld surface?

A4: Common causes include: insufficient electrode drying (excessive hydrogen content after moisture absorption), environmental humidity >80%, uncleaned oil/rust on the base material surface, and excessive current leading to rapid cooling of the weld pool.

IX. Contact Us

For procurement, wholesale, or to learn more about discount information, please contact OCEAN WELDING. We provide cost-effective and high-quality E7018-H4R low-hydrogen welding electrodes to meet the diverse needs of industrial welding.

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