Hard facing Monel 400 w/ Stellite 6

[CADCAMTech]

thread725-194498

I see that this question has been asked before in the tread above, but I am wondering where I would find documentation relating to how to properly apply Stellite 6 to Monel 400. I have found another form on the AWS website (

https://app.aws.org/forum/topic_show.pl?tid=11912)

that talks about issues when welding high Cr materials to high Ni/Co alloys, but I am having trouble locating technical documents relating to this issue. Any help would be greatly appreciated. Thanks.

 

[metengr]

https://www.osti.gov/servlets/purl/791763

 

[CADCAMTech]

Well you made that look easy. My google fu must not be up to par. I will read through it thank you.

I have also found this document

https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19720022816.pdf

. Page 68 states that the following weld compositions should be avoided "(4) Any Monel deposit, if dilution by more than 6- to 8-percent chromium is anticipated". I am no expert but I think it is trying to say that any weld that results in an increase of between 6-8% chromium over the normal base materials chromium content can cause cracking issues. And since Stellite 6 is approx. 29% Cr and Monel 400 has 0% this is likely to happen unless a "buttering" layer like described in the previous thread is used.

I am looking to create a weld procedure to hard face Stellite 6 to Monel 400. We require about .090" of Stellite, the remaining wall thickness below the Stellite is at the most 0.140" and I am not sure how much room we would need to apply a layer of the suggested Inconel 625 first.

Does anyone have any suggestions for alternative hard facing materials that would simplify this procedure. The part is for downhole oilfield use and would need to meet the requirements of NACE MR0175-3. We have had similar parts made of steel hard lined before but we are now being asked if we can provide Monel.

 

[dhengr]

CADCAMTech:
Could you flame-spray that .09” thickness on a relatively small part in some semi-automatic process. A robotic holder for the spraying head or a revolving part holder, or some such? Could you flame spray a thin buttering layer with the right material which would minimize the dilution or alloy mixing?

 

[CADCAMTech]

dhengr:

We currently have a flame spray capabilities, we use it to hardface cylinder OD's which we then grind down, its an automated process where the part turns and the gun travels down the length of the part so it would be within our capabilities. We use a Metco 5P-II gun if you are familiar with what that is, but this would not allow us to spray the ID geometry that we need to, we would have to look at some kind of attachment or different gun. With the ID of the part being around 1.00" I am not sure if this is possible, but I will look into it thanks.