scholarly journals Combined experiment and first-principles study of the formation of the Al2O3 layer in alumina-forming austenitic stainless steel

RSC Advances ◽  
2017 ◽  
Vol 7 (26) ◽  
pp. 15727-15734 ◽  
Author(s):  
Nan Dong ◽  
Yongfeng Qiao ◽  
Caili Zhang ◽  
Jian Wang ◽  
Guangwei Fan ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Oxide Layer ◽  
First Principles ◽  
Multilayer Structure ◽  
Al2o3 Layer ◽  
First Principles Study ◽  
The Matrix

Combined experiment and DFT research on the formation of the Al2O3 layer in AFA stainless steel is presented. The oxide layer has the multilayer structure with outer Cr2O3 and inner Al2O3 due to the diffusion of Al from the matrix to the Cr2O3 slab.

Simple Estimation of Deformation-Induced Martensite in Stainless Steel

2005 ◽  
Vol 297-300 ◽  
pp. 500-506 ◽  
Author(s):  
Hidefumi Date
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Magnetic Force ◽  
Volume Fraction ◽  
Tensile Deformation ◽  
Electric Resistivity ◽  
Electric Resistance ◽  
The Matrix ◽  
Simple Estimation ◽  
Measured Resistivity

To estimate the volume fraction of martensite induced in 304ss type austenitic stainless steel during tensile deformation, the electric resistance of the specimen was measured using the four-point-probes method at the temperatures of 77, 196 and 293K during the deformation. The magnetic force of the deformed specimen was also measured using a permanent magnet to determine the strain at which the martensite was induced initially in the specimen. The parallelepiped model was suggested to separate the effects of the deformation and transformation on the electric resistivity because the resistivity was influenced by the evolution of the martensite and the growth of the defect in the matrix at a constant temperature. The parallelepiped model consisted of m columns with n pieces of the cubic element and was assumed to be a group of small electric resistors. The volume fraction of the martensite estimated using the measured resistivity and the model was compared with the experimental results reported by other researchers and then it was clarified that the volume fraction of the martensite estimated by the model was in agreement with the volume fraction measured by the experiment.

scholarly journals Intergranular and Pitting Corrosion in Sensitized and Unsensitized 20Cr-25Ni-Nb Austenitic Stainless Steel

CORROSION ◽  
10.5006/3725 ◽  
2021 ◽  
Author(s):  
Ronald Clark ◽  
Choen Chan ◽  
W. Walters ◽  
Dirk Engelberg ◽  
Geraint Williams
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Grain Boundary ◽  
Grain Boundaries ◽  
Pitting Corrosion ◽  
Intergranular Corrosion ◽  
Niobium Carbide ◽  
Ion Concentration ◽  
Kelvin Probe ◽  
The Matrix

Advanced gas-cooled reactor (AGR) oxide fuels used in the UK are clad in bespoke grade 20%Cr-25%Ni-Nb austenitic stainless steel. Electrochemistry was first applied to correlate the breakdown potential with chloride ion concentration, temperature and pH for this alloy. At near-neutral pH the unsensitized material exhibited a linear E<sub>b</sub> = A + B log10[Cl<sup>-</sup>] relationship, where A = 0.7 V (vs. SCE), and B = 0.098 V/decade. Scanning Kelvin probe force microscopy revealed grain boundary regions in the heat-treated material up to 65 mV less noble to the matrix, whereas un-dissolved niobium carbide (NbC) precipitates were up to 55 mV more noble to the matrix. In-situ time-lapse microscopy and post-corrosion observations confirmed that sensitized grain boundaries were susceptible to pitting corrosion, further developing along intergranular corrosion pathways. It has however been shown that micro galvanic coupling between the Nb precipitates and matrix and / or sensitized grain boundary regions is not a factor in corrosion initiation as all experiments were performed under external potential control. Post corrosion observations showed the presence of pits at NbC precipitates promoting grain boundary corrosion. It is postulated that corrosion initiates at NbC precipitates as a pit, and when in close vicinity to Cr-depleted grain boundaries, then propagates along grain boundaries as intergranular corrosion.

Creep ruptures of AISI 347 austenitic stainless steel foils at elevated temperature of 750 ℃

2015 ◽  
Vol 231 (6) ◽  
pp. 516-522
Author(s):  
H Osman ◽  
FM Nor ◽  
YM Hamdan ◽  
MN Tamin
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Creep Damage ◽  
Primary Creep ◽  
Second Phase ◽  
Precipitate Coarsening ◽  
Second Phase Particles ◽  
The Matrix ◽  
Dislocation Movement ◽  
Rupture Properties

The creep rupture properties of AISI 347 austenitic stainless steel foil used in compact recuperators have been evaluated at 750 ℃ in the stress range of 54–221 MPa to establish baseline behavior for its extended use. The creep curve of the foil shows that the primary creep stage is brief and creep life is dominated by tertiary creep deformation with rupture lives in the range 3–433 h. Power law relationship was obtained between the minimum creep rate and the applied stress with stress exponent value of n = 4.25. The creep damage tolerance parameter for specimen tested at 750 ℃ and 54 MPa indicates that creep fracture takes place by precipitate coarsening mechanism. Nucleation of voids mainly occurs at second-phase particles (Cr23C6 carbides). The improvement in strength is attributed to the precipitation of fine niobium carbides in the matrix which prevents dislocation movement of the microstructure.

Multi-Layer Metal Matrix Alloy Surfacing Composite Material Fusion Research on the 45Mn-Austenitic Stainless Steel-(Cr-Ni) System

2013 ◽  
Vol 813 ◽  
pp. 148-152
Author(s):  
Yu Ping Zhao ◽  
Yu Hai Xu
Keyword(s):  
Stainless Steel ◽  
Composite Material ◽  
Composite Materials ◽  
Austenitic Stainless Steel ◽  
Abrasion Resistance ◽  
Metal Alloy ◽  
Fusion Welding ◽  
Resistance Testing ◽  
Carbon Equivalent ◽  
The Matrix

This article in view of the 45Mn-austenitic stainless steel-(Cr-Ni) system composed of metal alloy surfacing multilayer composite materials of the fusion mechanism research, through the hardness testing, impact test and analysis of the abrasion resistance testing, the results show that: Cr-Ni surfacing welding metal alloy system has good abrasion resistance, but the fusion welding the gender is poorer, as long as the matrix in martensite properly morphology of carbon dioxide, its hardness &abrasion resistance may achieve in, high carbon equivalent to achieve performance, show that the alloy elements Mn composite materials plays an important role in improving the wear resistance. Then define the matrix with 45Mn as metal materials, with austenitic stainless steel as sandwich bond, Cr-Ni system alloy metal as surfacing welding surface layer, a new multi-level composite material with excellent comprehensive performance. For multilayer compound material field research provides a theoretical basis.

Microstructure after Solution Annealing of the Nuclear Grade Austenitic Stainless Steel DIN 1.4970

2021 ◽  
Vol 1016 ◽  
pp. 1147-1152
Author(s):  
Ronald Lesley Plaut ◽  
Angelo Fernando Padilha ◽  
Flavio Beneduce Neto ◽  
Leandro Gomes de Carvalho
Keyword(s):  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Heat Treatments ◽  
Steel Matrix ◽  
Solution Annealing ◽  
X Ray Diffraction ◽  
The Matrix ◽  
Annealing Heat Treatment ◽  
Complementary Techniques ◽  
Annealing Heat

The main objective of the present work was to characterize the phases that are present after solution annealing in the microstructure of the titanium stabilized austenitic stainless steel W.-Nr. 1.4970, developed as a candidate material for fast breeder reactor fuel cladding. The crystalline structure, chemical composition, quantity, size, morphology, and distribution of the phases present in the microstructure after solution annealing heat treatments were studied in detail with the help of several complementary techniques. Chemical dissolution of the matrix has been performed using the Berzelius solution and the extracted residue has been analyzed by X-ray diffraction in a high precision camera. Three phases have been observed and identified after solution annealing heat treatments performed in the 1090 to 1300 °C temperature range, namely: (Ti,Mo)C; Ti (N,C) and Ti4C2S2. The Ti-nitride and the Ti-carbosulfide did not dissolve in the steel matrix up to 1300 °C, on the other hand, the solubility of the (Ti,Mo)C raised strongly with temperature. A solution annealing heat treatment is recommended for the W. Nr. 1.4970 stainless steel.

Oxide Film Morphology and Composition Analysis of TP304H Austenitic Stainless Steel at High Temperature

2011 ◽  
Vol 117-119 ◽  
pp. 917-920
Author(s):  
Mao Lin Liu ◽  
Zhi Wu Wang ◽  
Wei Wei
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Austenitic Stainless Steel ◽  
Oxide Film ◽  
Film Growth ◽  
Composition Analysis ◽  
Metallic Elements ◽  
X Ray ◽  
Temperature Diffusion ◽  
The Matrix

The oxide scale of TP304H austenitic stainless steel was analyzed with SEM, X-ray, and ESA after being oxidized at 650 °C, 750 °C and 850 °C for different time. The results show that: the initial oxide film consists of needle-like cores. With the heating proceeding, the needle-like cores grow up gathering into granular cores, and then new needle-like cores grow up on former granular cores, and gradually grow into flakes which continue to gather into more granular cores then. As the oxide film becomes thicker, this process is in continuous cycle. The subsequent needle-like or flakey cores form on the basis of previous granular cores. The content of metallic elements is analyzed to find the law of diffusion and oxidation. As the figure shows the Fe of the matrix diffuses outward and the oxidation takes place at the oxide film-gas interface, which means a series of reactions does not occur inside the matrix. Below the temperature of 650 °C, the growth of oxide film is relatively slow, while above this temperature diffusion and displacement of metallic elements and oxide film growth rate accelerates. The oxide film is easy to fall off when reaching to a certain thickness, which means that TP304H stainless steel is not suitable in high-temperature and oxidative environment for long service.

Influences of Nitrogen Content and Aging Precipitates on Pitting Corrosion Resistance Properties of High Nitrogen Austenitic Stainless Steel

2013 ◽  
Vol 448-453 ◽  
pp. 102-106
Author(s):  
Zu Rui Zhang ◽  
Zhen Ye Zhao ◽  
Chun Zhi Li ◽  
Zhou Hua Jiang ◽  
Hua Bing Li
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Austenitic Stainless Steel ◽  
Nitrogen Content ◽  
Pitting Corrosion ◽  
Corrosion Potential ◽  
High Nitrogen ◽  
Pitting Corrosion Resistance ◽  
The Matrix ◽  
Nose Temperature

This study is concerning the influences of nitrogen content and aging precipitates on pitting corrosion resistance properties of high nitrogen austenitic stainless steel (HNS) through potentiodynamic polarization method. The microstructure of aged HNS is analized by scanning electron microscopy (SEM). The main results obtained are as follow: the formation of intergranular, cellular Cr2N and intermetallic χ precipitates makes the depletion of Cr and Mo in the matrix and deteriorates the resistance to pitting corrosion in aged specimens. Cr2N starts to precipitate in the form of lamellar structure to cellular precipitates, the pitting corrosion drops to about 0 VSCE. HNSs perform the same tendency that the pitting corrosion potential firstly decreases then increases and reduce to the minimum value at nose temperature. All the pitting corrosion potential of HNS-B aged for 2h at different temperature presents more than that of HNS-A. The pitting corrosion resistance is mainly controlled by nitrogen content before great precipitates of cellular Cr2N and intermetallic χ phase rich in Cr and Mo. It is also mainly controlled by the content and the type of precipitates after great precipitates of cellular Cr2N.

Sign in / Sign up

Export Citation Format

Share Document