Abstract
This paper highlights some recent efforts to extend the use of medium-Mn steels for applications other than intercritically batch-annealed steels with exceptional ductility (and strengths in the range of about 1000 MPa). These steels are shown to enable a range of promising properties. In hot-stamping application concepts, elevated Mn concentration helps to stabilize austenite and to provide a range of attractive property combinations, and also reduces the processing temperatures and likely eliminates the need for press quenching. The “double soaking” concept also provides a wide range of attractive mechanical property combinations that may be applicable in cold-forming applications, and could be implemented in continuous annealing and/or continuous galvanizing processes where Zn-coating would typically represent an additional austempering step. Quenching and partitioning of steels with elevated Mn concentrations have exhibited very high strengths, with attractive tensile ductility; and medium-Mn steels have been successfully designed for quenching and partitioning using room temperature as the quench temperature, thereby effectively decoupling the quenching and partitioning steps.
Highlights
Medium-manganese steels with Mn concentrations in the range of about 5 to 10 wt. pct. have been explored over the past decade as potential options to provide “3rd Generation” Advanced High StrengthSteel (AHSS) sheets for automobile bodies, with excellent combinations of strength and ductility.These steels are most commonly employed in the intercritically batch-annealed condition, where an ultra-fine microstructure is obtained, and extensive Mn partitioning to austenite helps to stabilize substantial amounts of austenite, providing effective transformation-induced plasticity (TRIP) and attractive tensile property combinations
Mn alloying are less than those employed in twinning-induced plasticity steels, and their tensile ductilities are greater than leaner-alloyed Advanced High StrengthSteel (AHSS) products employing alternative processing approaches
The results show that the tempering step decreases the work hardening rate and tensile strength while increasing ductility; austempering decreases the work hardening rate and tensile strength while increasing ductility; austempering decreases the strength to a lesser degree while enhancing ductility
Summary
Medium-manganese steels with Mn concentrations in the range of about 5 to 10 wt. pct. have been explored over the past decade as potential options to provide “3rd Generation” Advanced High Strength. Steel (AHSS) sheets for automobile bodies, with excellent combinations of strength and ductility These steels are most commonly employed in the intercritically batch-annealed condition, where an ultra-fine microstructure is obtained, and extensive Mn partitioning to austenite helps to stabilize substantial amounts of austenite, providing effective transformation-induced plasticity (TRIP) and attractive tensile property combinations. Intercritical annealing may be employed in the hot-band condition, to obtain the requisite Mn partitioning, while softening the microstructure before cold-rolling These steels are of particular interest at tensile strength levels of about 1000 MPa, as the levels of. A variety of challenges are associated with medium-Mn steels, such as very large yield-point elongations in some instances, and sensitivity of mechanical properties to small changes in annealing temperature.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
