Modeling of the Kinetics of Strain-Induced Martensite Transformation and the Transformation-Induced Plasticity Effect in a Lean-Alloyed Metastable Austenitic Stainless Steel

This article investigates the influence of temperature and strain on second-phase transformation strengthening and the resulting mechanical properties in a lean AISI 301LN austenitic stainless steel within a temperature range of -60 to 180 degrees C. The volume fraction of martensite evolved is determined using nondestructive magnetic Ferritescope measurements that are adjusted by using a calibration factor of 1.7, which is established using the saturation magnetization measurements, X-ray, and neutron diffraction measurements. The kinetics of strain-induced martensite transformation (SIMT) as a function of strain and temperature is accurately described by a set of modified constitutive Boltzmann sigmoidal equations at temperatures below 75 degrees C. For this steel, the M-d (30/50) temperature is determined as 61 degrees C. The absolute M-d temperature is established as approximate to 109 degrees C, and no athermal transformation to martensite is observed upon cooling to -270 degrees C using cryogenic neutron diffraction facilities. Extended JMAK analysis of the transformation is used to shed light on the mechanism of martensitic transformation. It is found that the transformation-induced plasticity (TRIP) effect due to SIMT is at a maximum at 75 degrees C, which is the maximum elongation temperature (MET) and calculations are performed regarding alloy development which will reduce the MET to room temperature.

Automated summary

This study investigates the mechanical properties of a lean AISI 301LN austenitic stainless steel under various temperature and strain conditions, revealing the influence of martensite transformation strengthening on the material's behavior. Various measurement techniques are used to accurately describe the kinetics of strain-induced martensite transformation at different temperatures, providing insights into the alloy's performance at different operating conditions.