mechanical properties of aluminum killed plain carbon steel 1

[rerpelo]

Hello everyone. This is my first post so please bear with me.

I work for a manufacturing company that generally used 1010 tubing to make machined carrier sleeves. Our supplier has left the market, causing our stock to run low. We have recieved quotes from several sources for aluminum killed 1018 and 1020 material - higher carbon steels with finer grain and good ductility. Our product standards - which have mechanical property and composition requirements - are written for 1010, but we are considering re-writing the standard to include different compositions of steel.

Here are my questions:

1) How does the aluminum killed process change the mechanical properties of 1018 and 1020 material?

2) What are the general applications for 1018AK and 1020AK material? When would they be used instead of plain 1018 and 1020?

I have on hand a copy of "The Making, Shaping, and Treating of Steel". It is a good technical reference for production, but I am more interested in the advantages/disadvantages and mechanical property information.

- Rich

 

[TVP]

Rich,

In the 21st century almost all steels are killed, which means using Si, Al, or similar during the steelmaking process for deoxidizing the molten bath prior to making alloy additions, etc. Addition of aluminum also refines the prior austenite grain size. Answers to your specific questions are as follows:

1. Not much. Both Si and Al killed grades can be fine grained, so the difference in mechanical properties is usually insignificant. However, if the Si grade is refined with V, then it will tend to be a little stronger.

2. It is not really helpful to think of these grades as either Al killed or plain. It is best to think in terms of a) deoxidation method, b) grain refining method (if any), and c) desired performance. With today's modern steel mills and manufacturing techniques, the choice of deoxidation method, grain refining method, and control of non-metallic inclusions are very closely connected. This means that one steel mill may prefer to use only Si deoxidation while another one prefers only Al, or they use a mixture depending on the customer's application. One issue with Al usage is that any remaining inclusions in the steel will be aluminates or globular aluminum oxides, which are more detrimental to cutting tool life than silicate inclusions. This may not be a problem if the steelmaking process produces a relatively clean steel. ASTM E 45 is one method for rating inclusions.

The more significant issue to confront is changing from grade 1010 to either grade 1018 or 1020. 1018 & 1020 will both be significantly stronger and harder than 1010 with all else being equal.

 

[stanweld]

In addition to TVP's statements, Aluminum killed 1010 steel will have greater deep drawing properties than Silicon killed steels. The 1020 steels will not be deep drawing, aluminum killed or not(if deep drawing is part of your manufacturing process).

 

[rerpelo]

Thanks to both of you for the clarification. So to summarize what the two of you are saying (and please correct me if I've misunderstood):

* The mechanical property differences between a 1010 and 1010AK are negligible. This is also the case for 1018 and 1018AK, and 1020 and 1020AK.

* An AK processed steel would be used in the same applications as its non-AK processed counterpart, but may actually provide more strength.

 

[stanweld]

Straight aluminum killed steels have poor weldability using the electric resistance welding process.

 

[metengr]

Regarding elevated temperature mechanical properties that was not mentioned above, the Al-killed, fine grained, C-Mn and C-Mo steels will have a greater susceptibility to graphitization versus Si-killed steels.

 

[TVP]

rerpelo,

I am going to edit your summary as follows:

* The mechanical property differences between a 1010 (silicon killed, fine grain) and 1010 (aluminum killed) are negligible. This is also the case for 1018SKFG and 1018AK, and 1020SKFG and 1020AK.

* An AK processed steel can be used in many of the same applications as its non-AK processed counterpart, and may actually provide more strength than a coarse-grain steel.

Keep in mind what I said in my previous email: there is no such thing as plain 1010 or plain 1018. The options look something like this:

1. killed or not killed (quite unlikely these days) - killed with Al or killed with Si
3. fine grain or coarse grain - Al killed is automatically fine grain while Si killed can either be fine grain or coarse grain

 

[theedudenator]

What is the standard way to call out fine grained on an engineering spec?

Is it best to reference an ASTM type spec?
Or would one need to say "1018 fine grain"

But then what spec would define the term "fine grain"

 

[metengr]

theedudenator;
I would recommend you obtain a copy of ASTM A 29, this is a standard specification for General Requirements for Steel Bars, Carbon and Low Alloy.....

Get a copy, all of the necessary information regarding grain size and reports, etc is there.

http://www.astm.org/cgi-bin/SoftCart.exe/index.shtml?L+mystore+gyhm8818

 

[CoryPad]

Here is an example taken from ASTM A 516/A 516M Standard Specification for Pressure Vessel Plates, Carbon Steel, for Moderate- and Lower-Temperature Service. This type of steel requires fine grain structure for improved low temperature toughness.

4. Manufacture
4.1 Steelmaking Practice— The steel shall be killed and
shall conform to the fine austenitic grain size requirement of Specification A 20/A 20M.




Regards,

Cory

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