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,
https://materials-welding.blogspot.com/
https://www.linkedin.com/groups/122787
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