What is difference between Incoalloy 825 & Inconel 625 2

[sunny8sapar]

Dear Friends.

We have a test separator for offshore oil platform. As per drawing the vassel has to be overlaid with Incolloy 825 but the vendor has done with Inconel 625. The vendor is now arguing that the Inconel 625 is having higher Nickel and Chromium content and has better corrosion resistance properties.

Please let me know the difference between these two and which one is suprior?

Thanks & regards,
Sunny Sapar

 

[micalbrch]

Inconel 625 has a much higher Chromium and Nickel Content than Incoloy 825. So, that is true. Therefore I would agree with your vendor.

 

[XL83NL]

better corrosion properties .... under what circumstances?
Most would argue any Ferrari is 'better' than a Dacia Duster, but Id rather take the later when going off-road.

 

[OGMetEngr]

Alloy 625 has higher chromium, nickel, and molybdenum. Someone help me here, I'm having trouble thinking of an application in which Alloy 825 would have superior corrosion resistance over Alloy 625.

 

[SJones]

Me too, plus the fact that 625 is less problematic with regard to weld overlaying which probably accounts for the switch. Nevertheless, the change should have gone through due process and should not have ended up with a question on an internet forum after the fact.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

 

[metengr]

You should review the information below;

http://www.nickelinstitute.org/~/Me..._AlloyedNi_Cr_MoWeldingConsumables_14011_.pdf

 

[weldstan]

Incoloy 825 would be nearly impossible to weld overlay without hot cracking. It could readily be explosion bonded or roll bonded. In general 825 is welded with E/ER NiCrMo-3.

 

[EdStainless]

Because of its reasonable cost units would typically be made from solid 825, it is a high alloy stainless steel.
625 is a Ni based alloy with much better high temp properties than corrosion resistance. Just based on raw material values 625 is 3-4 times the price of 825.

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