Magnetic measurement of strain-induced martensite formation in Fe–30Ni steel

ABSTRACT

This investigation focuses on deformation-induced plasticity in Invar-type steel alloys. The effect is being studied in an austenitic model alloy, containing 30 wt-% of nickel. Its temperature dependent mechanical properties are being presented. Furthermore, the martensitic phase content has been determined by magnetic means in an alloy with two ferromagnetic phases for the first time. The results show that the α′-martensite formation within the austenitic phase with primarily wavy glide mechanism allows an increase in ductility of around 10% at the M_sσ temperature of −5°C. This is the point of maximum uniform elongation. Near the M_s temperature, a microstructure of 70 vol.-% deformation-induced α′-martensite can be achieved.

KEYWORDS:

• Invar
• α′-TRIP
• deformation-induced martensite formation
• high-alloyed austenitic steel

Acknowledgements

The authors particularly acknowledge the support through realisation of and counsel regarding the ferromagnetic measurements by Professor Dr. Ferenc Tranta, Miskolc University, Hungary. As well as the support through realisation and evaluation of XRD measurements by Dr.-Ing. Christian Schimpf and Dipl.-Ing. Christiane Ullrich, Institute of Materials Science, TU Bergakademie Freiberg Germany.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors would like to acknowledge the funding of this work by the German Research Foundation as part of the Collaborative Research Centre 799: TRIP Matrix Composite [CRC 799].