Regulating of tensile properties through microstructure engineering in Fe-Ni-C TRIP steel processed by different strain routes of severe deformation

Abstract

In this research, the effects strain routes during Repetitive Corrugation and Straightening by Rolling (RCSR) process in Fe-24Ni-0.2C TRIP steel are investigated from the viewpoint of microstructure development and tensile properties. It is observed that performing the RCSR process mainly leads to a drastic decrease in grain size along with an increase in dislocation density. It also leads to the occurrence of deformation-induced martensite. As well, results showed considerable improvement of Yield Strength (YS). It is also found that different routes induced diverse effects on the volume fractions of deformation-induced martensite. These effects instigated differences in yield strength, ultimate tensile strength (UTS), uniform elongation, and work hardening exponent. In that sense, the yield strength, after 25 cycles of the RCSR process, increased from 254 MPa to 872 MPa, and from 254 MPa to 921 MPa in routes A and B, respectively. In addition, results proved that ultimate tensile strength increased from 1210 MPa to 1362 MPa in route A and it reached 1460 MPa in route B after applying 25 cycles of the RCSR. Accordingly, it was observed that in route B, compared with route A, higher values of YS and UTS are achievable for the same amounts of uniform elongation.