The Europe structural steel market is shifting as green steel from DRI-EAF routes enters fabrication yards. Recent EUROFER data shows DRI-EAF melts contain sharply lower residual tramp elements (Cu, Sn, Ni) compared to scrap-based EAF steel, which directly affects weld repair consumable selection and base metal qualification.
Lower residuals reduce the risk of hot cracking in restrained joints, but they also change the HAZ microstructure evolution. The Outokumpu Stainless Steel Handbook confirms that tramp elements like copper and tin can segregate at grain boundaries during solidification, increasing crack susceptibility. With fewer tramp elements, the weld metal dilution tolerance becomes narrower, requiring careful matching of filler metal composition.
For structural grades like S355J2 and S420ML, standard WPS for traditional BOS steel are directly transferable per steelmakers' qualification reports. However, shops should requalify their PQR when switching from scrap-based to DRI-EAF base material, especially for critical welded details in fatigue-loaded structures.
Decision framework for a QC engineer:
- When specifying filler metal, choose low-residual grades (e.g., AWS A5.1 E7018-H4R) to match the clean base metal.
- For repair welding, use a lower-hydrogen process (GMAW with Ar/CO2 mix) to avoid hydrogen cracking in the clean, inclusion-free HAZ.
- If the project requires Charpy at -20?C or lower, run a new PQR with the actual DRI-EAF plate to verify HAZ toughness.
- For multi-pass welds, monitor interpass temperature strictly (max 250?C) to avoid grain coarsening in the absence of pinning inclusions.
A common pitfall is assuming that all EAF steel is identical. The tramp element difference between scrap-based and DRI-EAF melts can shift the transition temperature by 10-15?C, which may cause a Charpy test to fail at the required service temperature.
How are you handling green steel plate qualifications in your shop?