high chromium white cast iron nucleation 4

[nihil88]

I m a material engineer and work in a foundry. we produce high chromium white cast iron abrasive balls.

we cannot use %100 returns in smelting due to inhibition of starting nucleation.

But we use pig iron for starting nucleation grey-ductile iron smelting.

i want to produce high chr white cast iron with %100 returns

is it possible to add pig iron into high chr white cast iron melt for starting nucleation

sorry for my bad english

thanks for replies

 

[arunmrao]

I do not understand your term Nucleation, as is commonly understood by others. My advice, do not use 100% returns, restrict it to 35-40% only. The need for using pig iron is not understood.

In the case of Ductile Irons , pig iron addition is always beneficial to provide good nucleating sites , thus a better microstructure. A good charge mix, will contain 35-40% of pig iron.



I'm just one step away from being rich, all I need now is money.
( read somewhere on the internet)

 

[EdStainless]

I don't think that you will get there with 100% revert.
I presume that this is 25% Cr white iron.
You won't be able to home the chemistry balanced.

I don't understand your nucleation issue, there is no graphite in white iron. So there is no inoculation or nucleation like there is in grey iron.

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[nihil88]

we used pig iron for vitalization of melt when furnace waited for a long time.(nucleation)(grey-ductile iron)


we manufacture 17-19 Cr abrasive balls


I mean using 100% returns are impossible in production of 17-19 Cr ?

i wanna produce with %100 returns.

is there any method for apply this?

thank you

 

[arunmrao]

No, there can be no justification to use 100% returns. It must be restricted . 15-20% foundry returns,30-35% scrap returns and balance fresh charge . Else, you will end up with poor microstructure,leading to high wear rate.

I'm just one step away from being rich, all I need now is money.
( read somewhere on the internet)

 

[EdStainless]

I understand what you are saying about gray irons, if they are held in the furnace too long you loose inoculation and you need to 'freshen the heat' so that you get good graphite formation.
But if you are casting white iron that is not an issue.
What is an issue is controlling C, CE, Si, Cr, and temperature.

In some low quality products I have seen foundries get to 85% revert rates.
Getting above that will be very difficult.
You have trouble controlling chemistry, impurities build up, and even temperature control becomes more difficult.

Are you heat treating your white iron?
If you need help controlling the carbide structure you may need to look at that.
Which costs more to you, using clean metal in the melting or adding a heat treatment?

= = = = = = = = = = = = = = = = = = = =
Plymouth Tube

 

[arunmrao]

If you are making grinding media balls in high chrome, I would suggest, that you verify the grade of high chrome iron cast. They are all 11-12% Cr and not 18-19%. You are roughly 50% more expensive than competition.

I'm just one step away from being rich, all I need now is money.
( read somewhere on the internet)

 

[nihil88]

@EdStainless

yes we apply heat treatment process but we have old heat treatment furnace. flame furnace


we heat treat 280 minutes in 865-875 C for 11-
13 Cr balls.

and also 350 minutes in 975-985 C for 17-19 Cr balls


time and temperature depends on ball diameter.

 

[arunmrao]

There is no tempering after oil /air quenching?

I'm just one step away from being rich, all I need now is money.
( read somewhere on the internet)

 

[nihil88]

yes air quenching

 

[arunmrao]

You have a basket full of problems. Sincerely advise you to seek an expert's assistance. Online discussions will not be helpful.
GoodLuck

I'm just one step away from being rich, all I need now is money.
( read somewhere on the internet)

 

[nihil88]

thank you for advice