Steel melting - Arc vs Induction 7

[CdotS]

Can any one throw some light on the main differences in properties of steel castings made from an arc furnace compared to the castings from an induction furnace?

 

[mcguire]

Arc furnaces generally have poorer mixing because of their wide,shallow shape. Induction melting incurs great mixing. The upshot of this is that refining can be done better in an induction furnace, so if you want to decrease oxygen and sulfur to decrease inclusions, you can do it better in an induction furnace. Therefore induction melting can more easily achieve clean steel castings, and therefore better toughness.

 

[arunmrao]

Arc furnace melting permits a wide variety of charge input ranging from machine shop turnings and borings to heavy skulls. Dephosphorization and desulphurization is possible in arc furnace melting,ie metal refinement is possible. Also increase or decrease in carbon is possible.


In induction furnace slag refining operations is not possible. Hence a controlled charge input is necessary. Due to eddy currents there is better mixing in induction furnaces. But the same facility can be incorporated in are cfurnaces too by having electro magnetic stirrers,or by rabbling the metal manually.

Cleanliness of steel can be comparable if refractory practice and ladle metallurgy is controlled.

 

[EdStainless]

There are scale factors that tend to dicate which method is used. A 10T arc furnace is on the small side, and a 10T induction furnace is getting large.
Induction workes well if you have high quality feed avialable. You have great temperature control and it is clean and easy.
Arc is fast and efficent. You can melt about anything and slag refining practice is possible.

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Corrosion never sleeps, but it can be managed.

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[CdotS]

Thanks for your comments. Some foundries that supply steel castings claim that arc furnace melted steel parts are better than those made by the induction route. I do not have cast parts from both furnaces to compare. However, we have plans to do a through analysis later with respect to composition, microstructure, porosity, hardness, impact and abrasion properties. Cost might be a factor as arc furnaces can accept wide range of scrap steel and larger volume.

 

[arunmrao]

What are the grades of castings being produced in the arc furnace? S and P levels can be lower in arc furnace heat compared to induction furnace. I have had experience in producing similar grades of castings in arc furnace (5 tons capacity) and induction furnace (1 ton capacity),I have not found much variation in mechanical properties .

 

[mcguire]

There are many pluses and minuses for various melting methods, but nearly all have to do with economic issues, not the properties of the final product. As Arunmrao implies, ladle metallurgy is generally where properties are achieved. Good melting furnaces aren't necessarily good refining furnaces.
I would put the burden of proof on those who makes the claims. If they can't explain it in clear language, then it probably isn't true.

 

[Carburize]

To expand a little on mcguire's comment - I believe that the best steel-making practice combines both types of furnace. Electric arc for economic high speed melting of various incoming source material followed by ladle metallurgical treatment utilizing induction heating and stirring to achieve tight, accurate control of chemistry

 

[CoryPad]

Good post by [blue]Carburize[/blue]. I agree with you.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[CdotS]

Arunmrao, the steel grades that I am considering include low alloy steel with boron for abrasive wear applications. They will be heat treated to 45 to 50 HRC.

Thank you all for your valuable comments.

 

[gieter]

CdotS,

Electric Arc has according to my sources better intrincitic metallurgical purety. However this is important to obtain good mechanical properties, especially ductility. In your case where abrasive properties are sought, you will not notice this difference.

 

[steelmaking]

The induction furnace can't refine steel - decrease [C] and [P] content. Induction stirring don't give opportunity for good metall-slag reactions for deep desulphurisation.After melting in the induction furnace it need additional refining treatment into the laddle with Ar stirring and new slag.
If it have not additional refining of the metall, induction furnace is suitable for remelting a scrap with well known chemical composition. The advantage of indcution furnace is clean metall according nonmetallic inclusions and lower transformation costs(not using carbon electrodes).