Section F – Fluxes for submerged arc welding

This section includes submerged arc welding fluxes for CrMo low alloy steels, austenitic stainless steels, duplex and superduplex stainless steels and nickel base alloys. Further details on the specific products and related types can be found in the tables in sections; A,B, C, D & E
An indication of the basicity of the fluxes is given using a basicity index (BI) the most common of which is the Boniszewski index which is calculated from the molecular weight of each component using the following formula:
	CaO + MgO + BaO + CaF2 + Na2O + K2O + 0.5(MnO + FeO)
	SiO2 + 0.5(Al2O3 + TiO2 + ZrO2)
Flux consumption will vary slightly from one flux to another and also with welding parameters, the consumption increasing as the voltage increases. As a general approximation about 1kg of flux is consumed for every kg of wire melted; for estimation purposes a flux:wire ratio between 1 & 2 is normally used. The unfused flux can be recycled but the recycled flux should be limited to about 10% of the blend to avoid the build-up of fines.
There is a European specification (BS EN 760) for the classification of fluxes and also a DIN specification both of which allow a flux to be classified according to its characteristics. ASME/AWS does not have any standards for the classification of a flux they only classify wire-flux combinations. The ASME/AWS standards currently only cover mild and low alloy steel wire–flux combinations; there are no ASME/AWS standards for stainless steel or nickel base wire-flux combinations.

Data Sheet	Product	Description	Specifications
			AWS	BS EN / BS EN ISO
F-11	LA436	General purpose flux for low alloy steels	--	S A AB 1
F-15	LA491	High basicity flux for P91	--	S A FB 2
F-16	LA492	High basicity flux for P91 and P92	--	S A CS 1
F-20	SSB	Flux for duplex and superduplex stainless steel	--	S A AF 2
F-22	SS300	Flux for general purpose stainless steel	--	S A AF 2
F-30	NiCu	Basic flux for alloy 400	--	S A CS 2
F-35	NiCr	Basic low silica flux for nickel alloys	--	S A FB 2
F-40	L2N	Fused general purpose flux	--	S F CS 2
F-50	ES200	For electroslag strip cladding – for high speed	--	S A AF2 63 AC
F-52	ES400	For electroslag strip cladding	--	S A AF2 63 AC