Effects of Tensile Test Specimen Thickness on Elongation and Deformation Energy for Industrial Pure Iron

Abstract

Industrialpureironspecimenswiththethicknessvariedfrom0.2to2.0mmwereinvestigatedintensiletesttoexaminetheinfluencesof specimen thickness on elongation and deformation energy. Conventionally, the total elongation of tensile specimen can be converted by JIS 0202-1987 formula, which is related to the tensile test specimen thickness. However, in this experiment, it was noticed that there were number of factors which led to the inaccuracy in the result. The totalelongationwasinfluencedbythestresstriaxiality.AccordingtotheFEM(FiniteElementMethod)analysis,itshowedthatthestress triaxialityincreasedsignificantlywiththethinnerspecimen,thiswasduetothevoidgrowthbehavior,observedbySEM(ScanningElectron Microscope)underlowvoltage.Theseresultsrevealedthatvoidsnucleationandgrowthbehaviorinfluencedbythestresstriaxialitywerethe main cause for the formula incompatibility. After the tensile test, stress-strain curve can be obtained and categorized into the uniform and local deformation. The uniform deformation energy was not depended on the specimen thickness in contrast to duplex stainless steel of previous study. On the other hand, the local deformation energy lowered with the decrease in specimen thickness as with duplex stainless steel. These results indicated that the void nucleation andgrowthbehaviorhadasignificantimpactonthetotalelongation.

Quantitative evaluation of augmented strain at the weld metal during the Trans-Varestraint test

“…The bending deformation of the Trans-Varestraint test was simulated using the thermal elastic-plastic analysis. The mechanical properties of pure iron were obtained from the study conducted by Takeda [23]. A material model that considers the temperature dependence was used to simulate the bending deformation accurately.…”

Effect of γ-Phase Stability on Local Deformation Energy of α-γ Duplex Stainless Steel

“…Hence, dU can be used to evaluate the deformation behavior of specimens with different strengths. For these reasons, this study does not use local elongation itself, but rather evaluates the local deformation energy or the dU value of the system in the local elongation region obtained from the stressstrain curves from tensile testing 4,12,13) .…”