Effects of Pre-Stretching on the Mechanical Behavior of Cold-Rolled 5%Mn Medium Manganese Steel

Studies about the pre-stretching effect on the mechanical behavior of cold-rolled 5%Mn medium manganese steel have adopted optical microscopy, scanning electron microscopy, transmission electron microscopy and X-ray diffraction techniques. Results showed that pre-stretching would change the ferrite morphology from massive and lath-like to strip-like. With the pre-stretching increasing from 0% to 14%, the dislocation density and yield strength both grew gradually, which corresponded to growth from 6.49 x 1014 m-2 to 7.98 x 1014 m-2 and growth from 765 MPa to 1109 MPa, respectively. Meanwhile, the austenite volume fraction, elongation and product of strength and elongation were all reduced with the pre-stretch increase. The stabilized retained austenite with pre-stretch delayed the occurrence of the TRIP effect and improved the work hardening rate. As a result, the Luders band disappeared at 2% pre-stretch and the PLC band vanished from the stress-strain curve at 14% pre-stretch.

Automated summary

Studies have shown that pre-stretching affects the morphology of ferrite, increases dislocation density and yield strength, and reduces the volume fraction of austenite, elongation, and the product of strength and elongation in cold-rolled 5%Mn medium manganese steel.