Prediction of Martensite Volume Fraction in Fe–Cr–Ni Alloys

Abstract

Martensitic stainless steels, such as those in the AISI type 4xx series, have good corrosion resistance, good edge retention, high strength, high hardness, and good wear resistance. 1) Maintaining control over the amount of martensite is important when designing alloy compositions and determining heat treatment conditions, because of the contribution of martensite to the mechanical and electrochemical properties in these stainless steels. Dilatometric analysis has been widely used for determining quantitative volume fractions of transformed phases, and many investigations have provided analytical models for converting dilatometric data into volume fractions of the constituent phases. [2][3][4][5][6][7][8] However, most of these previous models have been mainly focused on heat-treatable low-alloy steels whose total amount of alloying element is below 5 wt%. The principle used in these models for dilatometric analysis is based on the relative atomic volume change between parent phase and transformed phase. This volume change is affected by the changes of the crystal structure, the lattice parameters of the unit cells, and the thermal expansion coefficient during phase transformation. The crystal structure of the phase is determined by the thermo-mechanical conditions, while the lattice parameters can vary due to the type and amount of alloying elements added as a consequence of having different atomic radii. [9][10][11][12] The purpose of the present research is to demonstrate an analytical model for predicting the volume fraction of martensite from a dilation curve by considering the effect of alloying elements in Fe-Cr-Ni stainless steel alloys. The dilation curves of Fe-Cr-Ni alloys with different chemical compositions were selected from literature to verify the analytical model, and the effect of alloying elements is discussed as part of this study.

Effect of heat treatment on the chromium‐depleted zones of a high carbon martensitic stainless steel

“…The X-ray diffraction results can also be applied to estimate the carbon content (wt%) in the retained austenite [23,24] :…”

Dilatometric Analysis and Kinetics Research of Martensitic Transformation under a Temperature Gradient and Stress

“…Li et al [ 13 , 14 ] suggested a dilatometric analysis model for the isothermal austenite decomposition in both hyper-eutectoid and hypo-eutectoid Fe–C steels. Some researchers took the effect of alloying elements on lattice parameters into account [ 15 , 16 ]. Garcia et al [ 17 ] and Kop et al [ 1 ] improved the model to analyze the transformations in continuously heating or cooling steels.…”