Regarding Tensile test.

[Mohit Aggarwal]

Dear Sir,

Greetings of the day!

I have one query, I have done Tensile test for full  Pipe specimen OD 25.7mm and thk 2.1 mm material SS 304L according to EN standard by calculating gauge length by consideration the OD of pipe with formula 5.65 x square root of Area which is coming 130 mm rounded off . In UTM machine I have select hollow pipe section and tensile strength is coming automatically with these settings.
But elongation is coming 32% and minimum required is 40%. We have done test by pressing the pipe ends.

Kindly let me know where is actual problem can oocurs.

I will be thankful to you.

Best Regards,
Mohit Aggarwal

[meisam shokri arfaei]

Dear Mohit

Why you press those two ends?

For full pipe testing, the normal way is using mandrel/plug in two ends and then doing the test. Pressing may cause unpredictable deformation in small size pipes and lead to un-normal fracture.

Then check your acceptance criteria. Minimum elongation required for different samples with different gauge length (proportional and non-proportional) may be different. Check required elongation related to your case. 

Then check the fracture surface and look for any defect which may cause unexpected fracture and then unacceptable elongation.

Also check the fracture area. It should be in the middle half of the gauge length. In other cases (fracture occurs out of gauge or near two ends) the test (usually sample preparation) may contains some errors and could be discarded and retested (It depends on your reference standard).

Also you may check ISO 2566-1 for elongation conversion in carbon steels. It may be helpful.

Regards

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M. Shokri Arfaei

ASNT NDT Level III

International Welding Engineer

Mob.:+98 912 1394023

[Harish Kannepalli]

Hi Mohit,

             As per any standard, you cannot perform tensile test by pressing tube ends. You have plug the ends with length as specified in standard.

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Regards,

Mr. Harish.

[Mohit Aggarwal]

Dear Sir,

Thanks for your guidance.Here we don't have the  manderl to plug in pipe. That's why we have done pressing the ends. I have checked with elongation required is minimum 40% for SS 304 material. Now I have done test with some fixture arrangement available which have some V type groove in between to hold the specimen and testing done of Base material of SS pipe. Now yield strength is coming less than required.

We will now do the test of welded samples with same fixture and of same size specimen.

Sir, Kindly confirm if a pipe having OD given then we will consider area as pi/4 (D*D-d*d) or Pi/4 D*D.

Best Regards,
Mohit Aggarwal
9619549616

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