Fully Killed Steel...

[Zeberoff]

I am reviewing an MTR for carbon steel pipe. Our Design calls for Grade 290 steel as per CSA 245.1. In the MTR, the material is certified to three different specs: ASTM53/API5L/CSA 245.1, all for the correct grade. Both API5L and CSA 245.1 require that the steel be semi or full killed while ASTM53 has no mention of it. Our design requirement is that the steel shall be fully killed. As for the deoxidizing agents, there is no aluminum in the chemistry, and the silicon is at 0.01% and 0.0%, while the manganese is at an average of 0.81%.

Questions:
1) Is this steel fully killed?
2) Is there a standard for fully killed steel (I know some metallurgy books say >0.1% Si and >0.03% Al for fully killed steel)
3) Since the material is certified to three different specs, while one contradicts the other two, can one certification be more true over another?

Your response is much appreciated.

 

[metengr]

As for the deoxidizing agents, there is no aluminum in the chemistry, and the silicon is at 0.01% and 0.0%, while the manganese is at an average of 0.81%.

Did you verify the above because Al may not be reported unless a full chemical composition is requested. Multiple certification means the heat of steel meets the requirements for the individual material specifications. Just because a material specification has no mention does not mean it is a contradiction.

Third comment - unless stated on the PO, the steel can be semi or fully killed.

 

[metengr]

2) Is there a standard for fully killed steel (I know some metallurgy books say >0.1% Si and >0.03% Al for fully killed steel)

The standard for killed steel will be based on the applicable material specification or as directed by the Purchaser. For example;
under ASME SA 210

5. Manufacture
5.1 Steelmaking Practice — The steel shall be killed.

Whereas, for another specification, like ASME SA 450 General Requirements;

3. Process
3.1 The steel may be made by any process.
3.2 If a specific type of melting is required by the
purchaser, it shall be as stated on the purchase order.


So, you get what you specify and paid for.

 

[Zeberoff]

Thanks Metengr, your response sheds clarity.

In the PO, we specify that it Shall be fully killed: "Casting and Deoxidization Process/Practice: Using continuous casting method, pipe shall be made from fully killed steel per Clauses 5.1 and 5.2 of CSA Z245.1-2007 (8th Edition)."

Our PO also stated a full chemical analysis is required per CSA 245.1, however, Al is not listed as an element while Si and others are. Does this mean that the steel may contain Al, and I can therefore not conclude that it is not fully killed?

Thanks

 

[metengr]

Usually, for chemical analysis aluminum may not be reported if the aluminum was used with silicone for deoxidation. I have seen this before. Second, aluminum can also be used for grain refinement, and in this case is usually reported on a MTR. If the Silicon level was required by the requirements of the PO/specification and is at or above 0.10% by mass, the steel would be considered killed.