"Usual problem (had personally faced) encountered while using Inconel
Overlay for SS 410S Clad. That too with P4 as the Base Material.
The issue is not due to Pickling or passivation rather due to the:
1) Differential thermal expansions between P4 base , SS 410S Clad and Clad
restoration by Inconel 625-
We can't do anything on this except to ensure the following :
a) During the clad restoration, the chamfering of the clad i.e 45° and
width of the clad restoration shall
be carefully considered.
b) Usually the corner pass between the Base & Clad shall be preferably
done by GTAW or low dia electrode
to get full fusion at the junction. If the fusion is in doubt , it will
open up during the subsequent passes/
layers of overlay and after PWHT also.
2) Here, the wagon track indication, is clearly associated with joint
design , bead sequence and Process parameters.
Lastly we need to know what was the PWHT Parameters used. This is very
important as we have different materials involved."
Regards
Principal Inspection Engineer- Welding/Metallurgy
Venkateshwaran Subramaniyam (Venky)
-----Fereidoun Majdnia/TPGAUH wrote: -----
----- Forwarded by Fereidoun Majdnia/TPGAUH on 01/12/2010 08:20 AM -----
"PEMMARAJU RAGHAVENDRA" <rpe@hzw.ltindia.com>
Sent by: materials-welding@googlegroups.com
01/12/2010 07:31 AM Please respond to
materials-welding@googlegroups.com
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Subject
[MW:4019] Linear Indications After Pickling and passivation and PWHT
Dear All,
I have a typical problem with my vendor who is manufacturing Coke drums for
us.
The stage of NDT including RT is such that we need to take RT before PWHT
and before overlay.
One of the section ( shell to Shell) under went the above process and
cleared. After that it was overlayed by AWS class Inconel E NiCrFe3
electrodes on base plates ( SA387 Gr.11 ClassII) with 410S cladding on
either side. Later the same was subjected to Pickling and passivation and
went for PWHT.
Now durng APWHT stage, when we are performing PT and RT, surprisingly we
are getting two wagon track linear indications on either sides of weld toes
from inside ( on cladding side) which are exactly the border junction of
ENiCrFe3 inconel and 410S cladding of the shell plates.
It is having a depth of around 0.5mm and width also same.
Could any one explain the cause of formation of this indication at the
above juncture. As per our estimation, it could have happend due to
pickling and passivation. Since another shell with above processes ( except
pickling and passivation ) has not got any such indications.
Thanks for your time and efforts.
Regards,
Raghavendra
Larsen & Toubro Limited
www.larsentoubro.com
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