Evaluation of Plastic Deformation Limit by Circumferentially Notched Tension Test

Abstract

Circumferentially notched and smooth round tension tests were carried out at room temperature with and without compressive prestrain in a hot-rolled ferrite-pearlite SM490B steel, and the effects of the compressive prestrain and the notch on the plastic deformation limit (PDL) were investigated. The PDL was defined as a termination point in a true stress-true strain curve which was caused by a ductile or cleavage fracture. The notch caused variations in the average stress-true strain curve but did not affect the true stress-true strain curve. A true strain at the plastic instability was determined by a work hardening exponent, regardless of the notch. On the other hand, the true strain at the PDL differed according to the notch. An axial stress at the PDL was found to be about 1 300 MPa, regardless of the ductile and cleavage fracture. KEY WORDS: plastic deformation limit; circumferentially notched tension test; true stress; true strain; axial stress. Fig. 1. The circumferentially notched tension specimen.

Prediction on Nominal Stress-Strain Curve of Isotropic Polycrystal Ti-15-3-3-3 Sheet by FE Analysis

“…17) K. Enami et al defined the onset point of ductile fracture as the plastic deformation limit (PDL). 5) In other words, the PDL means the onset of a very rapid decrease in load or stress. 5,17) In the present paper, a rapid decrease in the nominal stress is not obviously observed by the strain of approximately 0.18.…”

“…5) In other words, the PDL means the onset of a very rapid decrease in load or stress. 5,17) In the present paper, a rapid decrease in the nominal stress is not obviously observed by the strain of approximately 0.18. Hence, it is hard to determine the PDL.…”

“…1,2) Since the onset of localized necking cannot be theoretically predicted, the authors may set the second stage from P max to the onset of localized necking and the third stage from the onset of localized necking to final fracture. Plastic deformation limit (PDL) as the onset of ductile fracture 5) is also proposed in the third stage as in Fig. 1.…”

Prediction on Nominal Stress-Strain Curve of Anisotropic Polycrystal with Texture by FE Analysis

“…However, this consideration is not always experimentally true. 5,6) Under a load-controlled mode of deformation, the metal seems to proceed into fracture directly at P max as shown in Fig. 1(a), 6) although it is not easy to know how the metal deforms after P max .…”

“…1,7) Since the onset of localized necking cannot be theoretically predicted, the authors may set the second stage from P max to the onset of localized necking and the third stage from the onset of localized necking to final fracture. Plastic deformation limit (PDL) as the onset of ductile fracture 5) is also proposed in the third stage as in Fig. 1(b).…”