CD3MN weld ferrite

[bhollands]

I am having difficulty achieving a ferrite above the 35% minimum as required in NACE MRO 103. I am using E2209-16 rod and solution annealing the weld at 2150°F. The last test I did had a ferrite of 35% in the cap but only 30% in the midweld. I am restricting the interpass temperature to 300°F do I need to restrict it further?

Any help would be appreciated.

Bob

 

[metengr]

I would drop the interpass to a maximum of 200 deg F. Heat input is a strong variable for this material.

 

[metengr]

Second comment - your solution annealing temperature may be too high. Review the paper below, this is an excellent study done on qualification of CD3MN and wrought material. The solution annealing temperature to produce 50% austenite for several heats of this alloy looks to be at or slightly below 2012 deg F.

http://www.osti.gov/bridge/servlets/purl/861366-PD9mIS/861366.pdf

 

[jwhit]

In regards to the solution annealing temperature, ASTM A890 & A995 establish a minimum of 2050f for solution annealing, 2050-2100 should work well, time to quench is critical, the faster the better. If I remember correctly, these alloys revert to ferrite above ~2012f and then austenite grows out of the ferrite upon cooling which is backwards compared to other alloys.
Something else that may be helpful is to order electrodes with a FN of 55 or higher (WRC-92 Extended). Keep your interpass temps down as previously suggested and your heat input below 50kJ per inch.
You will do well if you fall between 35 and 40% by manual point count(ASTM E562) which is usually the requirement.
Good Luck
Jeff

 

[Guest102023]

I'm not surprised the weld ferrite is low.
2209 is formulated with significantly higher nickel - 9% vs. 5% - to compensate for the fast cooling rate. When you solution anneal you are starting over and cannot expect the weld and base metals to have comparable ferrite levels.

Metengr, no time to plough through the report but I am surprised it would be commercially possible. But I will accept your word on it, since you've been correct once or twice before ;-)

 

[Guest102023]

CCT for CA-6NM attached -

 

[Guest102023]

oops, wrong thread

 

[Hercules28]

To get more ferrite: higher annealing temperatures and faster cooling as a rule of thumb.


Ni is a austenite stabilizer so... lower Ni rod would help.