Elongation requirement for tensile test of PQR 2

[ukmet]

Dear All,
Can you please guide me:
1. Why there is no requirement for percentage elongation during tensile test of PQR as per ASME Sec IX?
2. Is tensile test value acceptable without elongation value?
3. Why gauge length for tensile specimen is 2"? Why it can't be less than that.?
4. Can the neck portion of tensile specimen of PQR be said gauge length as its just 6mm from both sides of welding with 1" radius from all sides? As it does not fulfill 2" gauge length criteria as described in SA-370.

Please do share your experience.

 

[metengr]

Here are replies to your questions;

1. Why there is no requirement for percentage elongation during tensile test of PQR as per ASME Sec IX?

Reply: This is not required because bend testing is performed as part of WPS qualification, which demonstrates if the weld and surrounding base materials have adequate ductility.

2. Is tensile test value acceptable without elongation value?

Reply: Yes.

3. Why gauge length for tensile specimen is 2"? Why it can't be less than that.?

Reply: Because testing is performed to an accepted standard and this includes specimen size requirements, reporting requirements also need to be standardized, including how UTS is determined, YS and elongation. These values can be influenced by using nonstandard dimensions or lengths.

4. Can the neck portion of tensile specimen of PQR be said gauge length as its just 6mm from both sides of welding with 1" radius from all sides? As it does not fulfill 2" gauge length criteria as described in SA-370.

Reply: No.

 

[Guest102023]

Elongation would be a meaningless result in a standard reduced section weld tensile test, because of the gross non-homogeneity of the sample.

The object of the ASME test is to try and force fracture in the weld zone, the only zone of interest.

 

[ukmet]

Dear Thank you very much for sharing your valuable experience. Dear metengr I could not understand your answer to 3rd point. Can you please elaborate?

By the knowledge you shared I understand that elongation value if found would not be proper. The laboratory which tested our tensile specimen gave elongation of 36% (SA516 Gr 70, 8mm thk. using process SMAW,SAW), which was unbelievable for me. This value would not be realistic keeping in view the facts you told. Am i right?

 

[metengr]

ukmet;
My response to your question 3 is that your modified gauge length should not be used to report elongation. Elongation is based on a standardized gauge length for consistency in reporting, anything outside of 2" will provide no meaningful results.

 

[ukmet]

OK I got it. Again thank you very much for sharing your knowledge.