# Mechanical Engineering help needed! Watch

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1. Still need help btw from someone
2. Hi, I`m 3rd year mechanical engineering student and I belive I know how to handle this problem .
First thing first, you need to calculate Chromium and Nickel equivalents of given steels and localise then on Schaeffler diagrams. The formulas are given on axes.

From the diagram you need to decode composition of material - how much martensite, austenite and ferrite will it contain.

For example for A:
Chormium equivalent = 20,5
Nickel equivalent = 12,4
So its about 10% ferrite and 90% austenite

After you do this, you need to choose the material that is appreciate for given application. I`d consider working conditions (low temerature) and manufacturability (large vessels are usually welded).

I hope that helped
3. (Original post by Eclipt)
Hi, I`m 3rd year mechanical engineering student and I belive I know how to handle this problem .
First thing first, you need to calculate Chromium and Nickel equivalents of given steels and localise then on Schaeffler diagrams. The formulas are given on axes.

From the diagram you need to decode composition of material - how much martensite, austenite and ferrite will it contain.

For example for A:
Chormium equivalent = 20,5
Nickel equivalent = 12,4
So its about 10% ferrite and 90% austenite

After you do this, you need to choose the material that is appreciate for given application. I`d consider working conditions (low temerature) and manufacturability (large vessels are usually welded).

I hope that helped

Cheers mate!

Do you know which would be the desired composition at a low service temperature. Austenetic, Martensitic or Ferretic - my first guess would we austentic since it is FCC structure and the FCC structure maintains a high toughness and not dependant on temperature? the ferritic is BCC and as the carbon content increases the pearlite phase increases, this usually decreases its toughness and the material is generally brittle at low service temps?? as for martenstic im not sure, but maybe it is generally a brittle material??? in respect to duplex materials im still working it out. any chance u might know more about this?
4. To be honest, I`m not 100% sure, but I belive you are right. Material needs to be ductile and tough, and not brittle, so austenite will probably be the best.

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