[MW:13223] RE: 13222] Impact test fail with A333 Gr6

Hi Solomon,

 

The problem looks to be in the the HAZ (FL & FL-2mm) on the pipe (SA 336 Gr-6) not much  in the weld metal or on the flange SA 350 LF2. A few things to look for :-

1. What were the impact properties of the pipe, impact temperature vs. impact values
2. What were the impact properties of the GNAW filler,impact temperature vs. impact values
3. Did you have any control on the heat input of the first two passes of GTAW. If so how much was the  calculated heat input??
4. What was the heat input in the first 2 layers of Submerged Arc Welding (SAW). It's better to be within 1.5-2.0 Kj/mm max  range for the first two layers.
5. In a single Vee  weld the  amount of dilution and effect of the heat input on the base metal & HAZ would be major in the first 2-3 passes. In this case the first two layers were done by GTAW. However as SAW is  a high heat input process, it may substantially over temper the subsequent layers of the weld or the adjacent HAZ.So it would be advisable to control the heat input in the first 2 passes of SAW.

The worst area look to be the root of the weld and the adjacent HAZ on  SA 333 Gr 6.If pipes are properly heat treated for guaranteed impact and so is the welding welding consumable  then the culprit would he the heat input.

 

Appreciate your thoughts and results of further follow-up on this issue.

 

Thanks.

 

Prada Goswami,P.Eng.IWE

Welding & Metallurgical Specialist & Consultant

Ontario,Canada.

Email-pgoswami@sympatico.ca,

pgoswami@quickclic.net

 

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From: materials-welding@googlegroups.com [mailto:materials-welding@googlegroups.com] On Behalf Of solomon
Sent: Saturday, December 17, 2011 2:47 AM
To: materials-welding@googlegroups.com
Subject: [MW:13222] Impact test fail with A333 Gr6

Dear everyone

I do PQR with following data

1. pipe SA 333 Gr 6 (12" SCH. 160) and Flange SA 350 LF2

2. Joint design is single V

3. Process GTAW+SAW

4. Preheat 80C Min. with burner torch

5. With out backing gas for root pass

6. Use ER 80-S-Ni1 (BOHLER) two layer with total deposited about 5mm and 

The result of tensile, bend, marcro look very good.

Before impact test I already RT, UT, and MT to confirm that no defect

The impact test (joules) done at -46C, on the location as follow and the result as shown

FL,Root(Flange)            112,86,89

FL+2,Root(Flange)         26,61,107

FL,Root(Pipe)                25,130,12  

FL+2,Root(pipe)             24,14,19

FL,Middle(flange)            131,108,132

FL+2,Middle(flange)         194,154,200

FL,Middle(pipe)              38,56,125

FL+2,Middle(pipe)           80,124,112

WM,Root                        42,80,79

WM,Middle                     24,106,92 

 

The acceptance criteria is average 20 and Min. 16

From the result above I have to retest again with

FL,Root(pipe)                 37,19,20

FL+2,Root(pipe)             14,12,25

So I need some help from you guides to analyze the cause of this result. In my opinion I think it may come from one of below reason

1. the preheat temperature too low due to the thickness of base mat about 34 mm so the heat dissipate very quick for GTAW. 

2. skill of welder may be not familiar with this filler (add Ni)  so the fusion to base material not deep enough even the NDE result not shown any defect

Due to I don have remaining mat. enough to do it many time I need some advice from yours

Thanks you in advance for your kind support

Bye

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