Union S 4 Mo is a low-alloy, creep resistant submerged arc (SAW) wire. It works in power plant, on superheaters, headers and pressure pipework in chromium molybdenum steels.
The wire is used on mechanised stations, on butt welds in plate and circumferential welds on tanks, and its copper coated surface improves current pick-up in the contact tip. The deposit resists creep at elevated temperature.
- Classification EN ISO: 14171-A S4Mo
- AWS classification: A5.23 / SFA-5.23 EA3
- Shielding: flux matched to the wire, no shielding gas
- Diameters: 4.0 / 4.8 mm
Plan the preheating and the post weld heat treatment to the WPS for the grade in hand, CrMo steels harden in the heat affected zone. Watch the wire stick-out and the position of the head against the weld centre line, under a flux you cannot see the pool and a mistake shows only after the slag is chipped off. Match the flux to this wire and check how dry it is, drying the flux decides the hydrogen level in the weld.
