SIF Chrome Super Duplex Welding Electrodes. ISO 3581-A : E 25 9 4 N LR 32. ISO 3581-A E 25 9 4 N LR 32. A rutile coated austenitic-ferritic electrode for welding of super duplex stainless steels like 2509 and 2594, in plate, and pipe applications. Self-releasing slag and an excellent weld appearance. Supplied in 4.0kg tin.