Effect of Cold Drawing on Microstructure and Mechanical Properties of 410 Martensite Stainless Steel Wire

Abstract

The microstructure and mechanical properties of 410 martensite stainless steel wire during the cold drawing process have been investigated by means of universal testing machine, optical microscope (OM) and transmission electron microscope (TEM) techniques. The results showed that the microstructure of 410 stainless steel was consisted of martensite and ferrite. During the cold drawing, when the wire was drawn from a diameter of 7.5 mm to a diameter of 5.0 mm, the average grain size decreased from 22.7 to 13.8 μm, the tensile strength increased from 504 to 741 MPa, elongation decreased from 38.2 to 13.1%. The strain hardening of the steel wire could be divided into two stages. In the first stage, the n value increased gradually and peaked at 0.85 which was associated with the plastic deformation of ferrite. In the second stage, the n value decreased to 0.25 which was associated with plastic deformation of martensite and the declined compatibility of the duplex phase. Moreover, the workhardening mechanism was discussed. The main work-hardening mechanism of 410 steel wire during the cold drawing process is fine grain strengthening and dislocation strengthening. When the steel wire was drawn from a diameter of 7.5 mm to a diameter of 5.0 mm, the strengthening benefit increased by 46.8 MPa and the dislocation strengthening increased by 173 MPa.