Tuesday, 1 January 2013

Temp. reduction in sub size specimen for Charpy impact test



We need to know way of calculation temperature reduction when we use sub size specimen.
Problem:
We have tested an A333 Gr.6 (4" pipe-6.3 mm thickness). Laboratory used a sub size specimen (55*5*10). and tested it at -48c. test temperature of A 333 Gr.6 is -45C (3 degree Celsius cooler temperature) Unfortunately absorbed energy was low and the test was failed. We 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 "
Is this clause applicable for this case??????
Really we don't know which one is correct?
  • (5/6.3) * 100 = 79% then we should not apply the above mentioned clause and we shall calculate reduction temperature and test my sample in cooler temperature(-45 + -3 = -48).
  • (10/6.3) * 100 = 159% then we should not apply the above mentioned clause and no need to reduction temperature and test my sample in MDMT(-45).

1 comments:

Anonymous said...

(5/6.3) * 100 = 79% then we should not apply the above mentioned clause and we 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 Impact 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

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