Mild steel & High Tensile Steel: Submerged Arc Welding

1.Profile：

For carbon steel submerged arc welding contains FLUX and welding wire. For welding process with both flux and wire from long range flat or horizontal welding.

In accordance with AWS A5.17 for classification of solid electrodes, composite electrodes, and flux-electrode combinations. In general, solid wire had been divided as Low-Manganese electrodes, Medium-Manganese electrodes and Hgih-Manganese electrodes. For Flux had been specified with tensile stretch grade, impact value, heat treatment or blend of crushed slag requirements.

 

There are two flux types: fused flux and unfused flux (bonded flux and agglomerated flux). Fused materials are queened in water, granulized and sieved to get fused flux finally, recommended welding current by low and medium level (≦1000A). Unfused fluxes are then made into particles with certain granular size. Products recommended for medium or high current welding (≧600A).

 

Welding conditions and welding beads forming relationship：

 

Welding conditions			Welding beads appearance
Stick-out length	long	Poor penetrate & Pre-humping
	short	Well penetrate & No hump
Current	large	Well penetrate & Pre-humping
	small	Poor penetrate & No hump
Amp	large	Poor penetrate with large bead high
	small	Well penetrate with narrow bead width
Welding direction	forward	Well penetrate & Pre-humping
	backward	Poor penetrate & no hump
Welding speed	fast	Poor penetrate, no hump and narrow bead width.
	slow	Well penetrate, Pre-humping and large bead width.

 

 

2.Working instruction：

(1)Storage management：

①To maintain the integrity of these products, electrodes must be protected from the atmosphere. All welding wires, regardless of package, should be protected from condensation.

 

②Submerged arc welding flux recommended re-drying. Sintering temperature is 350℃×1hr but fused flux is 200~300℃× 1hr.

 

③Unfused flux could be reused but need blended with virgin flux

 

 

(2)Caution：

①When groove welding recommend semi-automatic wire feeding for root passing.

 

②Appropriate flux covered for submerged arc welding could avoid porosity or pitting from welding bead.

 

③If working plate thickness over than 50mm, recommended welding width more than 2/3 from pre welding bead width. It helps to reduce delayed cracking. Therefore, preheat and post welding heat treatment need to be realized exactly.

 

④In order to avoid hydrogen diffusion in welding metal caused bead crack. Please be aware of preheat and PWHT for base metal over than 50mm.