Effect of specimen width on elongation

[tamal1475]

As per SA 213, minimum elongation specified for T12 is 30% on 50mm gauge length. However, we observe substantial difference in tested values of elongation between full section tubes specimen and 12.7 mm wide strip specimens. This is even after considering reduction factor for thicknesses less than 8 mm. Elongation values come regularly less than 30% for strips even when full section tests are well above. Is there any conversion factor? Is there any guideline or specification which can be used to resolve the issue?

 

[metengr]

What are your elongation values under Note B below of Table 4 for SA 213? You will be having reduced elongation, less than 30% for strip tension test thickness as indicated by Note B.

Note B For longitudinal strip tests, a deduction from the basic minimum elongation values of 1.00% for TP444, T23, T24, T91, T92, T122, and T911, and of 1.50% for all other low alloy grades for each 1⁄32 in. [0.8 mm] decrease in wall thickness below 5⁄16 in. [8 mm] shall be made.

We always have used subsize rounds machined from tubes under Note A with no issues reported for low elongation values.

 

[metengr]

Also look at ASTM E8 especially X1. FACTORS AFFECTING TENSION TEST RESULTS

http://daniel.fime.uanl.mx/labs/laboratorios/Agosto2012/practicas/ten.pdf

 

[EdStainless]

Full body tube samples will always give you a higher greater elongation than strip or bar samples. Part of the elongation in a tube is the collapse of the column, that can't happen in a solid sample.
With high elongation SS (over 40%) we typically see a difference of 5% between tube and strip samples.

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P.E. Metallurgy, Plymouth Tube