Monday, July 12, 2010

Re: [MW:5958] Inservice failure

Cr is low, hence carbide will form, which even solution annealing can not deal with much. You have wrong supplier.

--- On Mon, 12/7/10, Vaidehi Ganesan <vaidehi@igcar.gov.in> wrote:

From: Vaidehi Ganesan <vaidehi@igcar.gov.in>
Subject: Re: [MW:5951] Inservice failure
To: materials-welding@googlegroups.com
Date: Monday, 12 July, 2010, 2:21 PM

It looks like carbides are formed initially. Yes. It is required to do suitable solution annealing treatments to dissolve the carbides in solid solution. Moreover the impurities (P, S, Si ) segregate along the grain boundaries (during service) and reduces the fracture toughness of the material/ weld. We have faced similar problems with HP turbine blades. Failure must be due to carbide precipitation ( fairly big sizes) and segregation of minor elements along G.B.
All the best,
Thank you,
Vaidehi Ganesan.
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
----- Original Message -----
Sent: Mon, Jul 12, 10 12:49
Subject: Re: [MW:5947] Inservice failure

Dear Vaidehi,
 
The failed sample at the region of shearing or cracking has got Micro tested & found carbide precipitation in the Heat affected zone . the suraface above welding which is 20 mm far from welding is found ok in Micro.
Weather the requirement of solution annealing after welding?
as the tube was solution annealed previously.
 
 
Pankaj
 
 
 
 


 
On Sun, Jul 11, 2010 at 5:51 PM, pankaj abhang <pankaj.abhang1@gmail.com> wrote:


On Sun, Jul 11, 2010 at 5:42 PM, pankaj abhang <pankaj.abhang1@gmail.com> wrote:
Dear Vaidehi,
 Sorry for previous data incorrectly sended. 
   Please find the actual values:-
 
The Chemistry for the Tubes as given below
 
The Material Grade is-  SA249 TP 304.
 
C (MAX)- 0.08       Observed- 0.054
 
Mn (Max)- 2.00     Observed- 1.14
 
P (Max)-0.045       Observed-0.033
 
S (Max)-0.030       Observed- 0.006
 
Si (Max)-1.00        Observed- 0.42
 
Cr (Max-20 Min-18) Observed- 18.07
 
Ni (Max-11- Min -08) Observed- 8.21
 
 
 
Observed UTS Values- 651.4(Mpa)
 
Elongation- 62 mm
 
Hardness- 69-70
 
Micro- ASTM Grain size No.7
Heat Treatment- Solution annealed at minimum 1040 celcius & rapidly water quenched.
 
 
 
 
PANKAJ
 
 
 


 
On Sun, Jul 11, 2010 at 4:14 PM, Vaidehi Ganesan <vaidehi@igcar.gov.in> wrote:
What is the material, compositions?
best regards,
Vaidehi Ganesan.
=============================================================
Dr. Vaidehi Ganesan,
Metallurgy & Materials Group,
IGCAR, Kalpajkkam-603 102, India.
=======================================================
----- Original Message -----
Sent: Sat, Jul 10, 10 10:15
Subject: [MW:5924] Inservice failure

Dear Members,
 
We had supplied a Finned tube radiator after 1 year in service the header to tube joint getting shearing off near 10-15 mm from weld joint. what will be the reason for the failure.
 
Details are as given below-
 
Tube inside process fluid- Steam at 200 celcius
Tube MOC- SA 240 TP 249
Tube Thickness-2 mm
Header pipe -3"NB sch10s
Header MOC- SA 240 TP 312
Welding Joint- UW 16.1(d)
Welding Technique- GTAW
Working pressure- 15 bar(g).

 

 
PANKAJ
 

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