Strain-hardening of spheroidized high carbon steels

Journal Article · Thu Jan 01 04:00:00 EST 1976 · Acta Metall.; (United States)

DOI:https://doi.org/10.1016/0001-6160(76)90038-9· OSTI ID:7087783

Anand, L; Gurland, J

The strain-hardening behavior of spheroidized steels is examined in terms of continuum and quasi-continuum models based on the requirement that continuity be maintained at various boundaries in the two-phase polycrystals. For plastic strains up to 3.5 percent the increase in the flow stress appears to be composed of contributions arising from (i) dislocations stored in the material for (a) statistical and (b) geometrical reasons and (ii) an average back stress predominantly due to the presence of the unrelaxed plastic strain discontinuity between the ferrite matrix and the cementite particles. The latter contribution, which is a large fraction of the total strain-hardening increment, increases rapidly with strain up to a plastic strain of 3.5 percent and remains approximately constant thereafter. The attainment of the maximum value of the back stress corresponds to the observed transition in the overall strain-hardening rate (''double-n'' behavior). The experimentally determined components of the hardening increment due to the geometrically necessary dislocations agree well with the predictions of Ashby's theory. At strains greater than 3.5 percent, the average back stress remains approximately constant and the geometrically necessary dislocation density increases only slightly with strain. This indicates a deviation from Ashby's theory which predicts a continuous increase of this dislocation population with strain. The strain-hardening increments at these strain levels therefore appear to be controlled mainly by the increase in the statistical dislocation population.

• Research Organization: Brown Univ., Providence
• OSTI ID: 7087783
• Journal Information: Acta Metall.; (United States), Journal Name: Acta Metall.; (United States) Vol. 24; ISSN AMETA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
CARBON STEELS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DISLOCATIONS
FLOW STRESS
HARDENING
IRON ALLOYS
IRON BASE ALLOYS
LINE DEFECTS
STEELS
STRAIN HARDENING
STRESSES