Re: [MW:28251] Pulse GMAW-Black spots observed- Argon +2%CO2

Use Argon + 2% Oxygen. Check the cleaning of base metal and filler wire. Degreasing of filler metal may not be in order

On Sun, 9 Sep 2018 12:06 pm 'Shashank Vagal' via Materials & Welding, <materials-welding@googlegroups.com> wrote:

Hello,

Please try 100% Ar (confirm purity before use) and increase flow rate. Check general cleanliness, particularly of the filler and surfaces to be welded.

To remove black spots, pickle the weldments in

1.                                  30% nitric, 5% hydrofluoric - acids (rest water) at room temp for enough time till cleaned.

 2.        30% nitric (no HF). Time will increase.

Observe all safety precautions.

Best Regards,

Shashank C Vagal (Quality Adviser), (+91) 8082395502, 8779046302,

NEO METAL-ANALYST & NDT SERVICES

·       A-25, Geet Siddhi, Boradevadi, Moshi-Haveli, PCMC, Pune 412105

·      301, PRATHAMESH, M G Rd – Mahant Rd, Vile Parle East, Mumbai 400 057 INDIA

www.neometalanalystndt.com / enquiry@neometalanalystndt.com / nach_sam@yahoo.com

On Sunday, 9 September, 2018, 9:02:34 AM IST, Hrushikesh Sangamnerkar <hrushi612@gmail.com> wrote:

Dear expert,

Problem observed:

After welding Black spots are seen on weld. These black spots are not removed even after pickling & passivation.

MOC - SS 347

Filler metal - ER347

Dia. - 1.2mm

Gas used Argon + 2% CO2

Mode - Pulse

Flow rate - 10lpm

Note:

EDS analysis of weld doesn't show any carbon content.

Pl suggest some remedy by which these black spots can be avoided.

Regards,

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