Re: [MW:29150] Welding Invar 36

Sorry I realized that there were a few errors in my reply

Dear Girish:

First, why not using similar filler metal...? 

There are a few Invar 36 filler metals available, they should have Nb (better than Ti-alloyed filler metals) and make sure to make the weld as clean as possible to eliminate Sulphur and P (shall be very very low, especially S < 0.001). 

I do not know about your specification but some specifications require the longitudinal varestraint test (LVT) and especially double bead LVT for Invar 36 weld since the main issue with welding Invar 36 is solidification & reheat cracking, Ductility Dip Cracking (DDP). It might be a good idea to proceed with this test before commencement of the welding.

Regards  

Ramin  Kondori

Sr. QA/QC & Welding Engineer

-----------------------------------------------------------

PG-Dip. in Welding Engineering (IWE  AT  0070)

BSc. in Civil Engineering (IUT)

BGAS Painting Inspector

ASNT Level I&II

                        

On Sun, Feb 24, 2019 at 3:20 PM Girish Shejale <gshejale@mjbi.com> wrote:

Dear All,

 

Recently, we faced a problem welding INVAR-36/Alloy 36 (Ni 36%, Fe – 62%)  diaphragms used in gas turbines, which is block of 2 inch thickness approximately.

 

This is actually not a weld to weld joint, but only a material built up for building up thickness. Based on our experience we have found Nimonic 263 filler wire using TIG works well for material build up on INVAR-36 diaphragms.

 

Currently, we have a situation while welding with Nimonic 263, spattering occurs during welding. In fact, welding and melting is not taking place at all. Only spatters are observed, with some black color localized oxidation. We then tried using different filler wires such as SS308, IN-625 but the spatter and non-melting problem continued. We then tried with ERW method using Ni-Rod electrode and it worked to some extent, but lot of porosity was observed.

 

We are now thinking of using Alloy 36 filler wire, but not sure whether the problem will be eliminated.

 

Please let me know if anyone has any experience with a similar kind of problem, welding INVAR-36/Alloy 36 material.

 

 

 

Regards,

 

Girish Shejale

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