Killed carbon steel castings
Killed carbon steel castings
(OP)
Is there any way to tell if a carbon steel casting, A216-WCB in this case, has been supplied in the fully killed condition just by looking at an MTR?
There are maximum limits in the ASTM spec for Si (0.6% max)and Mn (1.0% max), which, as I understand it, are elements used to kill steel. Is there an established minimum ammount for these elements, that will tell me if the steel has been killed or not?
There are maximum limits in the ASTM spec for Si (0.6% max)and Mn (1.0% max), which, as I understand it, are elements used to kill steel. Is there an established minimum ammount for these elements, that will tell me if the steel has been killed or not?





RE: Killed carbon steel castings
Normally a good foundry practice would ensure silicon of about 0.3-0.4% and Manganese of around 0.8%. However,mechanical properties have to be satisfied,before acceptance. Hope it helps.
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"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year
RE: Killed carbon steel castings
Thank you for your reply.
Our typical casting contains Si 0.32~0.41 and Mn 0.527~0.714 (%/wt). Are these levels typically sufficient to accomplish a "full kill"? or is it a matter of Si & Mn levels plus the addition of Al and/or CaSi2 that are required to accomplish a full kill?
Also, ASTM doesnt seem to make any allowance for Al, so I'm assuming that if it is used in a WCB casting it would only be added in trace ammounts. Is this correct? My ASTM manual is really old, so my info might be out of date in respect to this question.
RE: Killed carbon steel castings
There is a level of Al ( like> 0.02% ) that is defined as "killed" but I have forgotten the exact number.
RE: Killed carbon steel castings
_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year
RE: Killed carbon steel castings
It is a requirement in an end-user's valve specification that all carbon steel castings be supplied in the "fully killed" condition.
I am of the opinion that the castings provided to us are already in the killed state as you mentioned. However, our factory says that they are not killed. For some reason the factory is under the impression that they need to employ some sort of vaccum system to deoxidize/de-gas the casting, and that since their castings are poured in an "open air" foundry the castings are not killed.
I think it is a classic example of the miscommunications that arise in the global market place we all find ourselves competing in these days.
I cant really tell why the customer has put the requirement in this spec. I am assuming it is an effort to prevent porosity that could provide a leak path.
Thank you to both of you for your input on this subject.
RE: Killed carbon steel castings
The standards for ASTM A216GrWCB,does not have anywhere a mention for melt treatment. However,if you read b]ASTM A703," General requirements for pressure containing parts"[/b] along with it,this standard says that special melting techniques like vacuum melting or AOD is not a standard practice,and should be adopted,only when specifically noted against individual alloy grade(read : speciality metals) in the standard.
Thus please check with your operations and advise them accordingly.
I have once again for clarity checked through Steel Castings Handbook,however no mention is made of any further refining of melt by AOD or other techniques.
Clearly,it appears to me a case of miscommunication.
Good Luck!
_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year
RE: Killed carbon steel castings
We procure castings SA 216 and SA 217. arunmrao is correct. If these castings are certified to meet SA 216, they are fully killed.
RE: Killed carbon steel castings
It sounds as if your end-user is confusing de-gassing (removing all dissolved gasses) with killing (removing dissolved oxygen). Foundry practices are not my area of expertise, and arunmrao, correct me if I am wrong, but I would think they would kill the steel as a matter of choice since trying to cast un-killed steel in sand molds would not likely lead to useable product (I am assuming these are sand castings).
In any case, if what the end-user is wanting is de-gassed steel, they should specify degassing. While degassed steels are fully killed, killed steels are not necessarily fully degassed.
rp
RE: Killed carbon steel castings
In case of processing special metals containing high levels of Ni,Cr, ,Al and very low levels of carbon,special techniques like,AOD or vacuum refining is required.
_____________________________________
"It's better to die standing than live your whole life on the knees" by Peter Mayle in his book A Good Year
RE: Killed carbon steel castings