Grain-Size Effects on the High-Temperature Oxidation of Modified 304 Austenitic Stainless Steel (original) (raw)
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Comparative study of high temperature oxidation behaviour in AISI 304 and AISI 439 stainless steels
Materials Research, 2003
This work deals with a comparison of high temperature oxidation behaviour in AISI 304 austenitic and AISI 439 ferritic stainless steels. The oxidation experiments were performed between 850 and 950 °C, in oxygen and Ar (100 vpm H 2). In most cases, it was formed a Cr 2 O 3 protective scale, whose growth kinetics follows a parabolic law. The exception was for the the AISI 304 steel, at 950 °C, in oxygen atmosphere, which forms an iron oxide external layer. The oxidation resistance of the AISI 439 does not depend on the atmosphere. The AISI 304 has the same oxidation resistance in both atmospheres, at 850 °C, but at higher temperatures, its oxidation rate strongly increases in oxygen atmosphere. Concerning the performance of these steels under oxidation, our results show that the AISI 439 steel has higher oxidation resistance in oxidizing atmosphere, above 850 °C, while, in low pO 2 atmosphere, the AISI 304 steel has higher oxidation resistance than the AISI 439, in all the temperature range investigated.
Corrosion Science, 2019
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High-temperature oxidation behaviour of nanostructure surface layered austenitic stainless steel
Langmuir, 2022
The present study investigates the high-temperature oxidation behaviour of nanostructure surface layered AISI 304L stainless steel. A severely deformed layer of ~300 μm thickness, consisting of nanoscale grains (~40 nm size) in the topmost region, is successfully developed using the surface mechanical attrition treatment (SMAT) process. The SMATed layer is substantially stable up to 700 • C; however, the surface hardness is reduced by ~37% at 800 • C for 25 h oxidation duration. Glow discharge optical emission spectroscopy and X-ray photoelectron spectroscopy analysis revealed the considerable difference in the chemistry and elemental distribution across the oxide scale of SMATed and non-SMATed specimens. Adherent, denser, and thinner scale, dominated by nanocrystals of Cr-and Mn-rich oxides, is formed on the SMATed steel. However, the Fe-oxide dominated scale containing micro-crystals is found on the non-SMATed specimens, which shows noticeable exfoliation. A high density of grain boundaries and lattice defects in the SMATed layer display admirable reactive diffusion properties of Cr and Mn during oxidation of steel, instigating the formation of a protective oxide scale. The SMATed specimens exhibit multiple zones in the oxide scale: (i) Cr/Mn depleted outer layer, (ii) Cr-/Mn-rich inner layer, and (iii) gradually decreasing Cr/Mn region.
Le Journal de Physique IV, 1993
Stainless steels of type AISI 304 and 316 were heated in air (1-5-15 minutes at 900-1000-1 100 OC) and the oxide layers formed on the surface were analyzed by XRD, CEMS, SIMS and FTIR. At these temperatures the main oxides are CrgOs and a spinel close to MnCr204 for polishing samples (with Fez03 for the chemically cleaned samples). The oxidation induces a Cr and Mn depletion from the metallic substratum and a phase transformation y (f.c.c.) + cu (b.c.c.) in a thin layer of the stee!s near the oxidesmetal interface.
Oxidation of Metals
The effect of p(H 2 O) and p(H 2) on the oxidation of 304L stainless steel at 600°C has been investigated in the present study. The samples were analysed by means of X-ray diffraction, Auger spectroscopy, and scanning electron microscopy equipped with energy dispersive spectroscopy. The results showed that at fixed p(H 2), the corrosion rate increased considerably with increasing p(H 2 O). At fixed p(H 2 O), the corrosion rate decreased slightly with increasing p(H 2). Duplex oxide scales formed during the exposure in all environments. The outer and inner layer consisted of Fe 3 O 4 and (Fe, Cr) 3 O 4 , respectively. The latter was mainly in the form of internal oxidation. The Cr-rich oxide formation was observed at the initial oxidation process before oxide breakdown. The Auger analysis also suggested the presence of Cr-rich oxide layer just after the breakaway oxidation. The results indicated that the rate-determining step in the corrosion attack is surface controlled or diffusion controlled through an oxide layer with fixed thickness over time.
Influence of surface preparation on oxidation of stainless steels at high temperature
Surface and Interface Analysis, 1993
Fourier transform infrared specular reflectance spectra at variable incidence have been recorded in order to characterize the oxide layers formed on both mechanically polished and etched surfaces of stainless steels (AISI 304 and 316). Depending on the surface preparation, the major oxides are either Cr2O3 and MnCr2O4 for polished samples or α-Fe2O3 and Fe3O4 for etched samples in the early stages of the oxidation in air at 900°C. Secondary ion mass spectrometry depth profiles confirm the schematic structure of oxide films (developed on polished surfaces during longer exposures) deduced from infrared reflectance study.
Cyclic Oxidation Behavior of the Super Austenitic Stainless Steel 904L in Air at 500–650 °C
Transactions of the Indian Institute of Metals, 2020
Cyclic oxidation behavior of the super austenitic stainless steel 904L was studied for 100 h over the intermediate temperature range from 500 to 650°C in air. The oxidized surfaces and cross sections of the oxidized samples were examined by scanning electron microscope (SEM-EDS), X-ray diffractometer and electron probe micro analyzer. The weight gain was found to follow nearly parabolic rate law. At 500 and 550°C, there was rapid weight gain up to the initial 5 h of exposure, whereas the rapid weight gain at 600 and 650°C was up to 10 and 25 h of exposure, respectively. The weight gain was drastically reduced during the later stage of exposure. Since the formed scales were thin, strong peaks of austenite (c)matrix were observed in all the exposed samples. There was formation of thin layer of Cr 2 O 3 on the specimens exposed at 500 and 550°C. Also, there was heterogeneous formation of iron oxides in some regions. The exposure at higher temperatures of 600 and 650°C led to the formation of different spinels of oxides such as FeCr 2 O 4 , NiCr 2 O 4 , FeNi 2 O 4 and others, along with Cr 2 O 3 and Fe 2 O 3 oxides.
High Temperature Oxidation of Aisi 439 Ferritic Stainless Steel in Synthetic Air Atmosphere
Jurnal Teknologi, 2018
Stainless steels may be used and exposed to aggressive gases at high temperatures. The oxidation behavior of AISI 439 ferritic stainless steel, was investigated by oxidation treatment at 850 ºC and 950 ºC, for 50h in Synthetic Air with 20% O2 atmosphere in a tubular oven and in a thermobalance. The oxidation kinetics of films are determined by measuring the mass versus oxidation time. The microstructure and chemical composition of the oxides were determined by Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS). Chemical analysis by EDS showed that films formed on AISI 439 stainless steel exhibited Cr as the principal element in the oxide film, in proportions to form the chromium oxide (Cr2O3) and the following elements: Mn, Fe, Ti and Si. Based on the oxidation kinetics, it was observed that steel oxidation follows the parabolic behaviour with increase in temperature and it produced the highest oxidation rate at 950 ºC and the lowest rate at 850 ºC.
ISIJ International, 1994
The influence of alloy surface preparation as induced by mechanical polishing and electropolishing on the oxidation behaviour of AISI 316 stainless steel in dry air under non-isothermal heating (6 K•min~1) followed by isothermal holding at 1 423 K is reported. Mechanically polished surfaces exhibit a shorter incubation period for initial oxidation but better oxidation resistance during isothermal holding as compared to electropolished surfaces. Such observation is attributed to enhancedoutward diffusion of Cr for easy and early establishment of Cr-rich oxide layer on the mechanically polished surfaces. Themorphologies of the scales and nature of their adherenceto the alloy substrates have beencharacterized by SEM. Distribution of the alloying elements like Ni. Cr, Mn, Mo. Si as well as Fe and oxygen across the oxide layers and the type of compounds formed have been examined by EPMA. EDSand XRD techniques. SEM examinations of the alloy/scale cross section for the mechanically polished and oxidized steel, supplementedby the X-ray imagesof the respective elements, indicate preferential formation of a continuous Cr-rich layer near the oxidelair interface along with two continuous bandsof dopedCr203at the scale/alloy region. Onthe other hand, the scale formed on electropolished surfaces of the steel showsfragmented Ni-rich and Cr-rich oxide areas at the bottom region of the scale with mostly compact Fe303-rich layer at the oxide/air interface.
Oxidation of Metals, 2011
A family of alumina-forming austenitic (AFA) stainless steels is under development for use in aggressive oxidizing conditions from *600-900°C. These alloys exhibit promising mechanical properties but oxidation resistance in air with water vapor environments is currently limited to *800°C due to a transition from external protective alumina scale formation to internal oxidation of aluminum with increasing temperature. The oxidation behavior of a series of AFA alloys was systematically studied as a function of Cr, Si, Al, C, and B additions in an effort to provide a basis to increase the upper-temperature oxidation limit. Oxidation exposures were conducted in air with 10% water vapor environments from 800-1000°C, with post oxidation characterization of the 900°C exposed samples by electron probe microanalysis (EPMA), scanning and transmission electron microscopy, and photo-stimulated luminescence spectroscopy (PSLS). Increased levels of Al, C, and B additions were found to increase the upper-temperature oxidation limit in air with water vapor to between 950 and 1000°C. These findings are discussed in terms of alloy microstructure and possible gettering of hydrogen from water vapor at second phase carbide and boride precipitates.