Welding:Hot Wire Tig (GTAW) Weld Overlay of Nickel Alloy (Such as C-686, C-2000, Alloy 59) on C.S.

[PressEquip]

Hello,

We're trying to develop a weld overlay of nickel alloys onto carbon steel. Client wants to achieve minimum of 1/8" THK of electrode chemistry at the final surface (Spark Test at the surface must have results that fall into the electrode chemistry requirements per ASME Sect. II, Part C (SFA-5.14).

We've tried sub arc and are getting too much iron dilution (even after 4 layers of sub-arc overlay, it's no guarantee the iron will be within range (max 5%wt))

Has any one have experience with hot wire tig for weld overlay of high nickel alloys? If so, please elaborate on what welding equipment and welding procedure details.

If we buy a hot wire tig set up, I would like to build on others experience and purchase a proven set-up.

Thank you for your time

A Fan of EngTips, share the knowledge

 

[metengr]

First, I would suggest you take some time and review the information below to get a good overview of what you need to accomplish;

http://www.twi-global.com/technical...ameters-on-dilution-and-corrosion-resistance/

Second, once you have digested the above information, you can search for arc machines that have proven hot wire TIG performance for weld overlays.

Third, you will need to review ASME Section IX and qualify a WPS using CRO essential welding variables.

 

[PCS30]

There are many kinds machines GTAW-HW. It is important to enter in contact with the manufacturer in order to understand the machines and accessories. An examples is ARC SPECIALTIES or FRONIUS. In another way, the requirement 5% is only possible by this process. If you try GTAW-manual this requirement need to be increased to 10% (see API 6A).

 

[weldstan]

You may wish to consider pulsed GMAW, especially run vertical down.

 

[samsam1973]

We use pulsed Hot wire TIG process in both flat and horizontal positions for Inconel 625 overlay and can comfortably achieve less than 5% dilution, meet NACE 0175 and API 6A requirements. You also have to be careful about the inconel 625 filler metal. There are only a handful of good Inconel 625 filler manufacturers. Techalloy 625 is one of them.

 

[PressEquip]

Thank you for the comments

Samsam1973, would you be willing to share which manufacturer made the hot wire TIG equipment that you're using? How many passes does it take to achieve less than 5% dilution?

Thanks

A Fan of EngTips, share the knowledge

 

[samsam1973]

I will pass the supplier info soon. less than 5% in 2 layers.

 

[samsam1973]

Press Equip. Please visit TIP TIG USA

http://www.tiptigusa.com/

There are distributors around N.A and Canada.I do have local distributor and i am in Canada.

 

[PressEquip]

samsam1973, thank you for the information. I'll loot at their website

Has your company tried overlaying nickel alloys with some of the newer MIG technology (Such as Fronius C.M.T. (Cold Metal Transfer)or Lincoln Electric S.T.T. (Surface Tension Transfer)) ?

I heard our shop tried it a couple years ago using the STT machine and the overlay ended up having micro-cracks at the grain boundaries (very bad news). Lincoln even took a spool of the MIG wire we were using and tried it at their R&D facility and got the same results and communicated that they didn't know what was causing it or how to remedy it. Based on that experience we've sort of given up on the new MIG technology for overlay of Nickel alloys.

I'm wondering if some company has developed it more and has a robust MIG system for nickel alloys. Any one have input on this topic ?

A Fan of EngTips, share the knowledge

 

[samsam1973]

Press Equip - I have used STT in the past for weld overlays including Inconel 625. We were successful in developing procedures for under 10% dilution. It is still manual(semi automatic)application. Fronius CMT was not around at that time. In recent years CMT is becoming popular big time. Trials are on going and i have to collect some info on the success of CMT for corrosion resistant overlay.(I heard bonding issues that come up with CMT and parameters are very finiky)
On the other hand TIP TIG can be attached to any fixture quite easily and made automatic and no issues of bonding. It is quite simple to use as maual torch for touchups / repair and is proven for immediate successful procedures.