Investigation of the Effect of Alloying Elements and Water Vapor Contents on the Oxidation and Decarburization of Transformation-Induced Plasticity Steels

Abstract

The present research deals with an investigation of the effect of alloying element additions (Si, P, and Sb) and water vapor content P H 2 O =P H 2 ¼ 0:01 to 0:13 ð Þ on the oxidation and decarburization behavior of transformation-induced plasticity (TRIP) steels in a gas mixture of 95 vol pct argon and 5 vol pct hydrogen/steam, by thermogravimetry (TG). The oxidation proceeds primarily as an internal oxidation front in the TRIP steels, but a thin external scale on the order of a micrometer thickness exists and is comprised primarily of fayalite ((Mn,Fe) 2 SiO 4 ) and ((MnO) x (FeO) 1Àx . The oxidation products are distributed near the surface and along grain boundaries. A comparison between calculated and measured oxidation curves indicated that the oxidation and decarburization are independent. The results for TRIP steels, both with and without an Sb addition, indicate that increasing Si and P contents accelerate, whereas Sb addition suppresses, both decarburization and oxidation rates. Water vapor content has no obvious effect on decarburization but has a pronounced effect on oxidation, and decreasing water vapor content decreases the oxidation rates.

Selective Oxidation and Reactive Wetting during Galvanizing of a CMnAl TRIP-Assisted Steel

“…12 alloy. This phenomenon was also recently observed by Zhang et al [52] for a 2.0 wt pct Mn, 1.5 wt pct Si, and 0.5 wt pct Al TRIP steel. The oxide morphology observed on this high Al-low Si TRIP steel was quite different than the oxide morphology observed on two high Si-low Al TRIPassisted steels annealed under similar conditions by the present authors.…”

Effect of Surface Microstructure on Oxidation of a CMnSi Advanced High Strength Steel

“…As mentioned previously, decarburization often leads to formation of ferrite at the surface of a steel, so studying the differences between oxidation of ferrite versus austenite 7) is indirectly looking at the potential effects of decarburization on oxidation. Studies based around thermogravimetric data on simultaneous oxidation and decarburization in AHSSs 29,30) have noted that decarburization depths are greater than internal oxidation depths, indicating they are independent processes. It is also noted that increasing external oxidation thickness seems to slightly hinder decarburization, indicating oxidation may influence decarburization kinetics.…”

Insight into selective oxidation of dual‐phase steel after annealing in pure H2 atmosphere at different heating rates and temperatures

“…And then, the steel is only composed of austenite and no ferrite could be found at 843°C. However, the phase transformation of the steel matrix from austenite to ferrite occurs during the oxidation because of the depletion of the alloying elements at high water pressure . Depending on the oxidation temperature, the depletion of Mn from the austenite steel matrix due to MnO precipitation may result in the formation of ferrite.…”

“…This means that higher temperature causes internal oxidations as a result of increased dissolved oxygen concentration at the surface and results in a more inward flux of oxygen diffusion from the surface to the bulk …”