904L

Known for delivering a fully austenitic, low-carbon weld metal enriched with Mo and Cu, these consumables exhibit exceptional resistance to corrosion in sulphuric, phosphoric, and various inorganic and organic acids. Not the typical choice for environments demanding resistance to concentrated nitric acid, they excel in scenarios involving severe chloride pitting media, where opting for overmatching nickel base weld metal, such as alloy 625, is recommended. Noteworthy as the preferred weld metal for certain lower alloy austenitics like Creusot UHB 34L and UHB 734L, especially in wet process phosphoric acid service, these consumables find versatile applications. Their usage spans tanks, process vessels, piping systems, agitators, rotors, and cast pumps and valves, catering to the needs of fertilizer, phosphoric, sulphuric, and acetic acid plants. Additionally, they prove invaluable in salt and seawater environments and are enlisted in select offshore applications, including overlays on mild and low alloy steels. The welding process mandates no preheat or post-weld heat treatment (PWHT), with interpass temperatures carefully regulated to a maximum of 150°C. It's crucial to exercise control over heat input, especially when utilizing larger diameter shielded metal arc welding (SMAW) electrodes.

904L is a nominally 20%Cr-25%Ni-5%Mo-2%Cu alloy with good corrosion resistance.

In the as-welded condition the weld metal microstructure is fully austenitic.

Suitable for copper-free variants of the listed alloys and also to overmatch leaner alloys such as 317L, 317LN, 317LM, 317LMN, 1.4439, 1.4440 and S31726.
EN W.Nr.: 1.4505 (X4NiCrMoCuNb20-18-2), 1.4506 (X5NiCrMoCuTi 20-18), 1.4536 (GX2NiCrMoCuN25-20), 1.4539 (X1CrNiMoCuN25-20-5), 1.4585 (G-X7CrNiMoCuNb1818), 1.4500 (G-X7NiCrMoCuNb2520).
ASTM: N08904.
PROPRIETARY: Uddelholm 904L (voestalpine), 2RK65 (Sandvik), Cronifer 1925LC (VDM), 254SLX (Outokumpu), Uranus® B6, B6M (Industeel).