Cast Iron EN-GJS-400-18LT

[Ignicolist]

Hi all!

I´m calculating a component with GJS-400-18LT cast iron. This component works with low dynamic loads, but it has to whistand a high loading (static) during the assembly.

The component has some big cylindrical holes with rounded corners. These holes recieve axial load, that produce high stress on the roundings. Produced stres is higher than Rp0,2 and they remain on the surface. A few mm inside, stress is much lower.

I don´t want to oversize the component only for one staic load cycle and I was wondering if I can calculate the part, assumin that the surface of the rounding will wrk with values hgher than Rp0,2. Something similar to plastification effecs on steel components.

My main questions are:
Does the considered material have some permanent deformation range, similar to steel? After the stress above Rp0,2, will this round remain plastified or deformed?
Do you have any complete stress-deformation curve for EN-GJS-400-18LT? I would like to simulate the behaviour of the part with non-lineal materials.

Thanks for the support!

 

[EdStainless]

Most CI has low enough ductility (and some other issues) that tensile and compression curves look rather different from each other. Either search for the compression data or have someone do some tests for you.

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P.E. Metallurgy, consulting work welcomed

 

[Ignicolist]

Sorry, I think my explanation was not the best.
All the critical stress are tensile stress on roundings. The component has not critical compression stress.

 

[btrueblood]

That's a ductile iron spec., with min. elongation of 18%. We use a similar material quite a bit. It has properties much like a cast steel part. Yes, it will permanently deform when stressed beyond the 0.2% yield strength. Like Ed said, you should ask the foundry for some representative test data for what you are doing. Another issue is that you might rupture parts that have internal flaws (porosity or inclusions) from the casting process.

 

[EdStainless]

You really shouldn't do this. If the high stress is just during assembly then you would have to do some NDT afterwards to assure that you didn't open a flaw of initiate a crack.

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P.E. Metallurgy, consulting work welcomed

 

[arunmrao]

As mentioned by others, this is a Ductile Iron grade with 18% elongation and it is not cast iron.
The matrix of this grade is fully ferritic with high ductility and impact strength, which guarantees use at temperatures down to minus 20°. Heat treatment is a part of the manufacturing process.