Hi Paresh Career001.

I am not speaking from knowledge of the code or the paper that you cite, but rather from my experience pulling tensiles on hot rolled and cold finished steel bars.

I'm choosing to use 1045 carbon steel for my illustration, I do not know off hand what the grades involved are in your code.

The % reduction in area actually has declines as the YS/tensile ratio increase:

Example data 2.5" 1045 steel Cold drawn, 100,000 psi TS; 85000 YS; % Elongation range 9-18%; %RA range 25-45;ys/ts=.85.

For hot rolled T&P 2.5" 1045 steel TS range 82-97000 psi; YS range 50-65000 psi; %elongation range18-28%; %ra range 35-55; YS/TS .61 to .67.

My explanation explanation for this data is that cold work has reduced the available ductility thus lower its measured value as %RA;

Heat treated (water quenched 1045)data is not so easily explained:

This data shows that as the YS/TS ratio increases from .727 to .765, the %ra increases from 36 to 54; However the YS/TS ratio inflects lower at 1200 F falling from .765 to .714 while the %RA climbs 7 points to 61.

This data shows that for tempered martensite microstructure the Yeld Tensile ratio and the % ra trend upward together as quenching stresses are relaxed, up to a point, at which case the yield / tensile ratio falls while the material continues to gain %RA.

I hope that this explanation of actual behavior in tensile testing in some way illuminates your question.

It's been a heck of a long time since university and frankly its been a few years since I developed this data in the lab...

If you look up CR4 member Abdelhalimgalala or KWETZ they will probably have more insight to your specific code question.

I'm just a former lab rat.

milo

thanks for your kind reply. seems like you know every bit of the your expertise.

Actually my question is regarding ASME Section VIII Div.2 Edition 2007.... this code gives lower wall thickness vessel compared to VIII-2 addenda 2006. so i wanted to know how one can presume that which material will give about how much % red. in thickness ( actual reduction in new code thickness comared to old code thickness )

so, how only YS/TS plays major role in % red. rather than cosidering basis for allowable stress in both code.