Ferrosilicon is an essential alloy of iron and silicon, manufactured usually in a submerged arc furnace by smelting quartz with coal. The process is energy intensive, and the high cost of production is justified by its irreplaceable role in steel making worldwide. A total of 5,915,400 tonnes of ferrosilicon was produced globally in 2022, of which 75.3% went to the steel making industry and 13.7% to foundries.
This article is about another use of ferrosilicon powder — specifically atomized ferrosilicon powder — in the manufacture of welding electrodes and flux cored wires.
What atomized ferrosilicon does in an electrode
Deoxidiser
Ferrosilicon is often added to welding electrodes as a deoxidising agent. During welding, and especially in processes like shielded metal arc welding (SMAW), oxygen from the atmosphere can react with the molten weld pool and form undesirable oxides in the weld metal. Ferrosilicon removes them by reacting with the oxygen to form slag, which lifts off the weld surface easily.
Alloying agent
Ferrosilicon carries both iron and silicon, and both are important alloying elements in welding electrodes. Silicon increases the fluidity of the weld metal, which makes the process easier to control and the weld easier to get right. Iron contributes to the strength and toughness of the deposit.
Controlled cooling
Atomized ferrosilicon can be used to control the cooling rate of the weld metal. By adjusting the composition of the electrode — in particular the amount of ferrosilicon — the cooling rate can be influenced, and with it the microstructure and mechanical properties of the joint.
Fluxing agent
In some cases ferrosilicon also acts as a fluxing agent. Fluxes protect the molten pool from atmospheric contamination and help carry impurities out of the weld metal. Ferrosilicon takes part in those fluxing reactions, improving the quality and cleanliness of the weld.
Arc stability
The presence of ferrosilicon affects the stability of the arc. The composition and properties of the electrode, ferrosilicon content included, can be tuned to hold a stable arc throughout the weld, which in turn gives better penetration and deposition rates.
Why atomized rather than crushed
Taken together — deoxidation, alloying, controlled cooling, fluxing and arc stability — atomized ferrosilicon does a great deal of work inside a consumable. The reason the atomized grade is preferred is the particle itself: formed from the melt rather than crushed from a lump, it is rounded and free-flowing, it does not carry the sharp fractured faces that pick up moisture, and it behaves consistently from batch to batch.
AIM Alloys LLP is India’s first BIS approved manufacturer of atomized ferrosilicon powder, and we supply it to quality matching international standards. Particle size distributions are made to customer requirement. Send your enquiry to info@aimalloys.in.