2553

These consumables are specifically designed for welding similar alloys, usually provided in cast form. The addition of copper enhances corrosion resistance in sulfuric acid environments and potentially increases robustness and wear resistance; however, toughness in the welded condition and pitting resistance in chlorinated media are reduced compared to alloys containing less than 1% Cu. Although the composition is carefully controlled to ensure a minimum pitting resistance equivalent (PRE) of 40, beneficial for welding super duplex alloys and maximizing pitting resistance in consumables with less than 1% Cu, it might be preferable to use them in non-sulfuric acid environments, unless a post-weld heat treatment (PWHT) is applied. Applications include
pumps and valves, corrosion and wear-resistant components, and processing equipment intended for use in the offshore oil and gas industries, as well as in the pulp, paper, textile, chemical, and petrochemical sectors.

25%Cr ferritic-austenitic superduplex stainless steels with nominally 25%Cr-8%Ni-3.5%Mo-1.5%Cu-0.2%N.

In the as-welded, or solution annealed condition, the microstructure is an austenite-ferrite duplex with about 25-60% ferrite.

• EN W.Nr.: 1.4515 (G-X3CrNiMoCuN 26 6 3), 1.4517 (G-X3CrNiMoCuN 26 6 3 3)
• ASTM: A351 & A744 gr. CD4MCu, A890 gr. 1A, A890 gr. 1B
• UNS: S32550, J93370, J93372, S39255+
• PROPRIETARY: Ferralium® 255–SD50, 255–SD40 (Langley Alloys), Uranus® 50M, 55, 52N, 52N+, 47N (Industeel), Ferrinox® 255 (Advanced Metals)

For standard welds, no preheating is generally required, and the interpass temperature must be kept below 150 °C. For castings and other highly constrained welding applications, a preheat-interpass temperature range of 100 to 225 °C is advantageous to prevent the risk of hydrogen-induced cracking. Consumables are designed to be used predominantly in the solution annealed condition. Castings invariably require solution annealing, and both the electrode and flux cored wire offer increased robustness with a slight decrease in toughness after solution annealing. The typical post-weld heat treatment is performed at 1120 °C for about 2-3 hours, followed by water quenching.