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Bored Bar AISI 86xx yield stress query

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morris9791

Mechanical
Feb 7, 2008
99
Dear Experts,

I have a query regarding the material properties of bored bar of approximate diameter 200mm OD.
From the AISI 8620 material data sheet, material properties are given for three different rounds diameter, i.e., 13, 25 and 50mm. One could interpolate to get an approximate figure for 100mm diameter section.
However, does a different manufacturing process affect the material properties even with the same heat treatment?
E.g. Is it ok to take the yield stress from AISI data based on 100mm diameter rounds when the bored bar is of 200mm approximately?

Any help or opinion will be welcomed.

Thanks
Eddie
 
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It depends on how the part is made. The reason the properties are listed for different diameters is because this alloy does not harden very deeply during traditional quenching plus tempering heat treatment, so a larger diameter part will not be as strong. Actually, this alloy is intended for carburizing, so that it has a tough core for fracture resistance and a hard outer surface for wear resistance. How do you intend to use your 8620 material?

Regards,

Cory

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What is the ID of your bar?

The physical properties will tend to approach those of a bar equal to the wall thickness as you are quenching from two sides.
 
Cory and unclesyd,

Thank you for your fast response. The material is intended for use as a ring gear mainly because of if its good shock resistance and strength properties. Approximate dimensions are 200mm OD and wall thickness 10mm.
I am just wondering is it correct to take yield strength values 100mm section(interpolated) from AISI 25mm round section considering this prototype will likely be a bored bar.
Would it be better to obtain some material strength data from the manufacturer instead(if they have it)? Is it possible that there may be a large differnce in actual yield and that based on my assumption?

Any suggestions are welcomed.
Thank you
Eddie
 
Do you want final properties after the gear is made? Or, for the material before making the gear?

How is the material processed? What is the order of the steps?

In general, you can't take the bar data sheet properties because they don't have the same processing schedule as a gear.

Regards,

Cory

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Cory,

I want final properties after the gear is made and heat treated.
I dont know how the material is processed, all I know that it may come from a bored bar since it is a prototype.
What steps do you suggest I take to investigate the final properties of this gear?

Kind Regards

Eddie
 
morris9791,
Sorry if I have not understood your question properly,but corypad has raised some very pertinent issues and as an end user you must be aware of these . Using data sheets of 8620 steel which does not take into cognizance the process details and end use may result in wrong inferences.

Your concerns are well appreciated,but you must be able to give more details other than the size and alloy.

Chocolates,men,coffee: are somethings liked better rich!!
(noticed in a coffee shop)
 
Dear Arunmrao,

There has been a slight understanding on my part regarding the issue I raised. It turns out that the manufacturer has the facilities to manufacture the gear AND heat treat it to our required physical properties.

Apologies for the misunderstanding. Thanks for the interesting replies.

Regards

Eddie
 
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