Re: [MW:16367] Temp. reduction in sub size specimen for Charpy impact test

 

Dear Farhang

REFER MY REPLY IN RED

 

Best Regards,
M.P.N.Muthukumaran

From: Farhang <hyperm2m@gmail.com>
To: materials-welding@googlegroups.com
Sent: Saturday, 29 December 2012 11:17 AM
Subject: [MW:16362] Temp. reduction in sub size specimen for Charpy impact test

Dear All

I need to know way of calculation temperature reduction when we use sub size specimen.

My problem:

I have tested an A333 Gr.6 (4" pipe-6.3 mm thickness). Labratoary used a sub size specimen (55*5*10). and they tested it in -48c. test temperature of A 333 Gr.6 is -45C and they tested it in 3c cooler temperature Unfortunately absorbed energy was low and my test failed.

But i see a clause in standard(SA-333/SA-333M) which described that:

" 14.1.2) When sub size Charpy impact specimens are used and the width along the notch is less than 80% of the actual wall thickness of the original material "
actual wall thickness i.e 6.3mm thickness of Pipe
Is this clause applicable for my case??????

Really i don't know which one is correct?

• (5/6.3) * 100 = 79% then i should not apply the above mentioned clause and i shall calculate reduction temperature and test my sample in cooler temperature(-45-3=-48).This is correct, With small correction.Kindly check the note below Table 6 of SA/A 333 "Straight line interpolation for intermediate values is permitted.So by calculations -45-4=-49.

SA/A 333 - 13.2 Test specimens shall be obtained so that the longitudinal axis of the specimen is parallel to the longitudinal axis of the pipe while the axis of the notch shall be perpendicular to the surface.

 

SA/A 333 -14.1.2 When subsize Charpy impact specimens are used and the width along the notch is less than 80 % of the actual wall thickness of the original material,

 

All sub size specimens will be 2.5x10, 5x10,7.5x10,etc. So for Imapct specimen one width should be always 10mm and second width along the notch  is restricted by thickness of the material being tested.  Hope this clarifies  

• (10/6.3) * 100 = 159% then i should not apply the above mentioned clause and no need to reduction temperature and test my sample in MDMT(-45).

** In the above text i use different color for digits because you can trace them easier.


Many Thanks
Farhang
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