904L

This consumable is designed to provide a fully austenitic low-carbon weld metal, enriched with molybdenum and copper. It is renowned for its excellent corrosion resistance in acidic environments, such as sulfuric and phosphoric, as well as in other types of both inorganic and organic acids. However, it is not the ideal choice for environments with concentrated nitric acid. For applications requiring chloride pitting resistance, the use of nickel-based over-alloyed weld metals, such as Alloy 625, is recommended. It is the preferred weld metal for certain low-alloy austenitics, such as Creusot UHB 34L and UHB 734L, especially when used with wet-process phosphoric acid. Typical applications include tanks and process vessels, piping systems, agitators, and rotors, as well as cast pumps and valves used for the production of fertilizers, phosphoric, sulfuric, and acetic acid. It is also suitable for brackish and marine environments and in some offshore applications, such as overlays on mild and low-alloy steels. No preheat or post-weld heat treatment (PWHT) is necessary; however, it is essential to control the interpass temperature up to a maximum of 150 °C, paying particular attention to the heat input, especially when using large diameter 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)