Böhler Union S 3 Si EH12K Submerged Arc Wire

Higher-manganese C-Mn SAW wire for steels up to S460

Böhler Union S 3 Si is a copper-coated solid wire for submerged arc welding of general structural steel grades up to S235-S460 (34 to 67 ksi on the US sheet). It is classified AWS A5.17 / SFA-5.17 EH12K and EN ISO 14171-A S3Si. With about 1.65 % manganese against roughly 1.10 % in an S2Si wire, it deposits a stronger weld metal, so it is the usual choice when plate strength and thickness make an S2Si weld marginal, for example in heavy pressure-vessel plate, structural sections and offshore steels.

Technical specifications

Parameter	Specification
Product type	SAW wire, unalloyed, copper coated, solid
AWS classification	A5.17 / SFA-5.17 EH12K
EN ISO classification	14171-A S3Si
Typical wire analysis, wt %	C 0.10; Si 0.30; Mn 1.65
Base materials	General structural steels up to S235 to S460 (34 to 67 ksi)
Diameters, mm (global data sheet)	2.0; 2.5; 3.0; 3.2; 4.0; 4.8
Diameters, inch (US data sheet)	5/64; 3/32; 1/8; 5/32; 3/16
Recommended SAW fluxes (Böhler)	UV 309 P, UV 310 P, UV 400, UV 418 TT, UV 419 TT-W, UV 420 TTR, UV 422 TT-LH
Approvals on data sheet	None listed; the Böhler webshop product page shows ABS, BV, DNV-GL and CWB marks for certain flux combinations

Choosing the flux and checking the approval

Seven fluxes are named on Böhler’s data sheet. Flux options in this Böhler range include

UV 418 TT.

for high-strength fine-grained steels with good toughness and

UV 400.

for general use. Marine and offshore class approvals attach to a specific wire-flux combination, a diameter and a test condition, so request the approval certificate for your exact pairing instead of assuming it from the wire alone. For lighter, less demanding joints

Union S 2 Si.

is the lower-manganese alternative.

Related Böhler SAW wire	AWS / EN ISO class	Typical steel
Union S 2 Si	EM12K / S2Si	C-Mn structural steel up to S420
Union S 2 CrMo	EB2R / S S CrMo1	1.25Cr-0.5Mo boiler and vessel steel
Union S 3 NiMo 1	EF3 / S3Ni1Mo	Fine-grained steels, Ni-Mo wire

Storage and wire handling

Copper-coated SAW wire protects itself from rust only while it stays dry and clean. Keep spools and coils in their original packing until use, store them off the floor in a dry room, and do not leave an opened spool on the machine overnight in humid conditions. Surface rust and dust shorten contact tip life, disturb feeding and add hydrogen to the weld. Before ordering, confirm the diameter, spool or coil type and the certificate level (for example EN 10204 type 3.1) that your project requires.

Documents and quotation

The Böhler Welding data sheet for Union S 3 Si (global edition, 03/2021) is attached. See the SAW Wire category for other grades. For a quotation, send diameter, packaging, quantity, flux and certificate requirements.