Re: [MW:29161] Re: Repairing a brazed crack by TIG / MIG Welding

1) We are repairing aero turbine shrouds by detecting cracks on them and then repairing surface cracks by conducting vacuum brazing.

Detected cracks by what method? Why repairing cracks by vacuum brazing if it will not long lasts?

2) However, this does not last long and when the shrouds return for repairs can we fill in the brazed cracks by TIG / MIG welding on the brazed surface.

What is the thickness of shrouds, yes as said you need to specify full configurations and can you share some pictures?

Brazed cracks have been fully removed, i mean cracks? Did your remove all the linear indication without any entrapment?

4) Alternately the question may be that Can we TIG or MIG weld on the brazed joint to repair.

Irrelevant to the case possible or impossible to do that you need governed procedure / repair procedure with owners approval to perform this scenario, secondly you simply cannot make a procedure because of melting points both varies and joining Vs fusion is far different as metallurgical changes will be at any consequences from solid to liquid or liquid to solid state.

Hence your case is to be scrutinized on the depth of cracks and length of the crack by contemplating the visual of real scenarios, at any case braze over weld is not acceptable.

Thanks.

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Regards,

MOHAMED MUNEEB MAHABOOB

From: sandeep kumar

Date: 2019-02-24 11:29

To: Materials & Welding

Subject: [MW:29146] Re: Repairing a brazed crack by TIG / MIG Welding

Hi

My answer based on general welding guidelines in your case as I have no practical exp in your issue.One thing,you didn't specify the base material & brazing filler wire details.

However back to topic, as TIG/MIG is a fusion welding process where a braze joint I consider as a partial solid state bonding process & are not considered as strength welds.

Now two possible scenario:

1. You remove the earlier braze joint completely and welded with TIG which will offer the optimal strength between the weld metal and the base metal

2. Failure to remove completely the braze weld and welded further with TIG will leave a weak point in terms of strength joint between the weld joining line of braze to base metal.

Hope it make sense.

Regards
Sandeep Kumar

On Friday, February 22, 2019 at 8:49:07 AM UTC+3, Enginayyars wrote:

Revered Experts

Please enlighten on the following:

1) We are repairing aero turbine shrouds by detecting cracks on them and then repairing surface cracks by conducting vacuum brazing.

2) However, this does not last long and when the shrouds return for repairs can we fill in the brazed cracks by TIG / MIG welding on the brazed surface.

3) I will not be able to share BPS or WPS for proprietory constraints.

4) Alternately the question may be that Can we TIG or MIG weld on the brazed joint to repair.

Warmest

engin...@gmail.com

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