WPB elbow tensile test

[MFQC]

Dear friends
we perform a tensile test on a sample from a batch of A234-WPB elbow to ensure that the data in certificate has mentioned right.
result for tensile and yield strengh was in the range of ASME SecII tables.
But the elongation was 3% lower than the minimum requirements.
As you know because of the elbow curvature , we have to straighten the sample. then we sent it for machining to prepare the tensile test specimen according to SA-370.
what is your opinion about this issue ? is this reduction in elongation a cause for rejection?
Does the cold work which we have done on the sample, has any effect on elongation?
what would you do in this situation?
Best regards

 

[MFQC]

No comments?!

 

[SJones]

I would ask for a repeat with a round bar test piece taken from an unflattened sample.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[bobjustbob]

If you have cold worked material in your gauge length then the %elongation will be affected. How much it is affected will depend on the amount of cold work and how much it is in your gauge length. I assume that the break was not in the work hardened area, is that correct? Were you using the same gauge length and cross section as the test method required in your specification and used by your supplier for testing? Was the %RA, tensile and yield all within specification and similar to the reported values on the CMTR?


Bob

 

[MagBen]

Cold work will decrease elongation.
The gage length, the strain rate, the size of specimen, and direction of deformation/cold work will all affect EL.
Measurement on part and on as-shipped bar/plate stock can make a difference as well.