A Review on Measurement Techniques of Deformation‐Induced Transformation Kinetics in Transformation‐Induced Plasticity and Transformation‐Induced Plasticity‐Assisted Steels

Abstract

Deformation‐induced austenite‐to‐martensite transformation is an important phenomenon that controls the flow behavior of transformation‐induced‐plasticity (TRIP) and TRIP‐assisted steels. Transformation kinetics and triggering strain are important parameters that need to be known during transformation. Both these parameters can be correctly determined by an accurate quantitative assessment of the austenite during deformation. Herein, both in situ and ex situ measurement techniques used for quantitative assessment of austenite during/after tensile deformation of the TRIP and TRIP‐assisted steels are reviewed. A comparison of various techniques such as X‐ray diffraction, neutron diffraction, Mossbauer spectroscopy, and DC/AC magnetic permeability is presented. Due to limited penetration power of the radiations, difficult access, and difficulty in setting up the measurement facility for the in situ measurements, X‐ray diffraction, neutron diffraction, and Mossbauer spectroscopy techniques do not yield accurate quantitative results and are time‐consuming. It is envisaged that an accurate quantitative assessment of austenite from the bulk of TRIP and TRIP‐assisted steel specimens is possible with magnetic permeability measurement techniques. Real‐time quantitative assessments can be made by measuring changes in the magnetic permeability due to changes in the ferromagnetic content during deformation. magnetic permeability measurements require extensive calibration for the accurate measurement of the phases during deformation of the steel.