Thread: Elongation at break vs Yield Strength vs Tensile Strength

Metengr, in our situation there is dynamic loading, so toughness is very important.  But I was looking for a correlation between toughness and elongation at break. But comparing sample 1 and 2, sample 2 UTS-YS= 7 ksi, while sample 1 UTS-YS=36ksi.  While both samples had identical elongation at break.  Which puzzles me.  I would expect the sample 2 elogation at break to be...

CR100; As an approximation, the area under the tensile stress/strain curve will give you some idea of material toughness (the larger the area and greater the toughness) but this approach should not be used in design. Instead, you should obtain fracture toughness values or perform Charpy V-notch testing to determine if you have adequate toughness for the intended service conditions.  

( What is the reduction in area at the fracture? Can you measure elongation dynamically during the test? Have you carefully looked at each sample for external reasons \(inclusions, surface defects, notches\)? , )

( Assume that both the test samples are from the same stock.If that is true,then you must closely look at the inhomogenities or any machining marks in the test samples to get such a variance. Also were the two tested by the same operator. I once had an interesting experience on a Hounsfield tensometer,where the zero was not set and misleading results obtained. , )

CR100, Although I can't answer your specific question, I'd suggest that you ignore that second set of test data.  You won't get a combination of 310KSI UTS and 12% elongation in any alloy that I know of (including multi-phase or Aermet). Regards, Terry

CR100, 1524 and maraging 300 steels do not have the same microstructure, so they will not necessarily produce similar strength-ductility relations.  For medium carbon martensitic steels (say 0.20-0.45% C) that are tempered at the same temperature and produce essentially the same strength/hardness, the elongation/fracture strain should be similar.  1524, 4130, and 5135 would produce similar elongation when...