Correlation between Microstructures and Ductility Parameters of Cold Drawn Hyper-Eutectoid Steel Wires with Different Drawing Strains and Post-Deformation Annealing Conditions

Abstract

The relationship between microstructures and ductility parameters, including reduction of area, elongation to failure, occurrence of delamination, and number of turns to failure in torsion, in hypereutectoid pearlitic steel wires was investigated. The transformed steel wires at 620 °C were successively dry-drawn to drawing strains from 0.40 to 2.38. To examine the effects of hot-dip galvanizing conditions, post-deformation annealing was performed on cold drawn steel wires (ε = 0.99, 1.59, and 2.38) with a different heating time of 30–3600 s at 500 °C in a salt bath. In cold drawn wires, elongation to failure dropped due to the formation of dislocation substructures, decreased slowly due to the increase of dislocation density, and saturated with drawing strain. During annealing, elongation to failure increased due to recovery, and saturated with annealing time. The variation of elongation to failure in cold drawn and annealed steel wires would depend on the distribution of dislocations in lamellar ferrite. The orientation of lamellar cementite and the shape of cementite particles would become an effective factor controlling number of turns to failure in torsion of cold drawn and annealed steel wires. The orientation and shape of lamellar cementite would become microstructural features controlling reduction of area of cold drawn and annealed steel wires. The density of dislocations contributed to reduction of area to some extent.

Heat Treatment of Steels

“…Jung et al [13] report on the relationship between microstructures and ductility parameters, including the reduction in area, elongation to failure, occurrence of delamination, and the number of turns until failure in torsion in hypereutectoid pearlitic steel wires.…”

Hydrogen-Assisted Microdamage of Eutectoid Pearlitic Steel in the Presence of Notches: The Tearing Topography Surface

“…Many papers have dealt with the study of different hardening and strengthening mechanisms after cold-drawing of pearlitic microstructures [24][25][26][27][28][29][30][31]. With regard to fracture (post-yield) behavior of pearlitic steels, one can find classical papers by Porter et al [32], Hyzak and Bernstein [33], Park and Bernstein [34], Alexander and Bernstein [35] and Dollar et al [36], and more recent works [37][38][39][40][41][42] dealing with plasticity/yielding behavior, as well as fracture performance.…”