1. Welding (Primary Method for Load-Bearing Connections)
Recommended Welding Processes & Setup
Common processes:
GMAW (MIG/MAG welding): Ideal for medium-to-thick sections (≥6mm). Use 80%Ar + 20%CO₂ shielding gas to reduce porosity and ensure stable arcs.
SMAW (Stick welding): Suitable for on-site repairs or thick sections (>12mm). Choose electrodes with low hydrogen content (e.g., E7018-G Cu) to avoid cold cracking.
FCAW (Flux-cored arc welding): Good for outdoor use (wind-resistant flux) and thick plates. Select flux-cored wires with weathering additives (e.g., AWS E71T-8-G Cu).
Critical Considerations for Welding
Filler metal matching: Use weathering-grade fillers (e.g., EN 1600 G 3Si1 (Cu) for MIG, E7018-G Cu for SMAW) to ensure the weld metal forms the same protective patina as the base steel-this prevents the weld zone from rusting faster than the parent material.
Preheating & interpass temperature:
For plates ≤12mm and ambient temps ≥5°C: No preheating needed.
For plates >12mm or temps <0°C: Preheat to 80–120°C to reduce hydrogen-induced cracking in the heat-affected zone (HAZ).
Keep interpass temperature below 250°C to avoid HAZ grain coarsening (which weakens toughness).
Post-weld treatment:
Grind weld beads to remove spatter or slag-this helps the weld area form a uniform patina.
For harsh environments (coastal/salt spray), apply a thin weathering steel passivation solution to the weld zone to accelerate patina formation.
2. Mechanical Fastening (For Detachable or Non-Load-Bearing Connections)
Recommended Fasteners & Installation
Fastener types:
Hot-dip galvanized high-strength bolts: For load-bearing connections (e.g., ISO 898-1 Class 8.8 or 10.9). Galvanization resists corrosion, but ensure the bolt material (e.g., alloy steel) can handle the same loads as S355J0WP.
Stainless steel bolts (316 grade): For decorative or coastal applications. 316 stainless steel has better salt spray resistance than galvanized steel and avoids galvanic corrosion (a risk if using carbon steel bolts with S355J0WP).
Self-tapping screws (weather-resistant coated): For thin S355J0WP sheets (≤3mm), e.g., attaching cladding to frames. Choose screws with a zinc-aluminum coating (Zn-Al) for long-term rust resistance.
Critical Considerations for Fastening
Avoid galvanic corrosion: Do not use plain carbon steel fasteners-they will rust faster than S355J0WP and may accelerate corrosion of the steel around the hole. Always pair with galvanized or stainless steel fasteners.
Pre-drilling: For thick plates (>6mm), pre-drill holes (slightly larger than the fastener diameter, e.g., 1mm extra) to prevent the steel from cracking during installation.
Sealing (optional): For outdoor applications, apply a weather-resistant sealant (e.g., polyurethane sealant) around bolt heads/washers to block moisture from entering the gap-this reduces crevice corrosion.
3. Other Attachment Methods (Specialized Scenarios)
Riveting: Rarely used today, but applicable for heritage-style structures or where welding/bolting is impractical. Use weathering steel rivets (matching S355J0WP's composition) to maintain corrosion resistance.
Adhesive bonding: For non-load-bearing decorative attachments (e.g., mounting signs to S355J0WP facades). Use epoxy-based structural adhesives designed for metal (e.g., 2-component epoxy with corrosion-resistant additives). Ensure the steel surface is cleaned (degreased, sanded) for strong adhesion.
