scholarly journals Identification of Inhomogeneous Temperature on Stainless Steel using Statistical Analysis

2021 ◽  
Vol 2084 (1) ◽  
pp. 012008
Author(s):  
Yuli Sri Afrianti ◽  
Husaini Ardy ◽  
Udjianna Sekteria Pasaribu ◽  
Fourier Dzar Eljabbar Latief
Keyword(s):  
Stainless Steel ◽  
Contingency Table ◽  
Compound Formation ◽  
Prolonged Heating ◽  
Light Blue ◽  
Σ Phase ◽  
Frequency Table ◽  
Long Time ◽  
Inhomogeneous Temperature ◽  
Chemical Etchant

Abstract Corrosion in stainless steel, abbreviated as SS, is still an exciting topic to study. Even though SS is a corrosion resistance material, this property will be degraded when exposed to high temperatures for a long time because of σ phase, such as a Fe-Cr compound, formation. The presence of this phase can be observed using a special chemical etchant solution that will give five specific colours to this phase: light brown, dark brown, bluish brown, light blue, and dark blue. In this study, the specimen sample is from ASTM A297. Furthermore, the metallography process is carried out to obtain microstructure images that describe the σ phase. Here, two grains were taken as objects to discretize with one of them was around the specimen sample center and the other was close to the boundary with the environment. The discretization resulted in a 2 x 5 frequency table, called contingency table, that is analysed by the independence χ2-test. The contingency table is also represented geometrically in cartesian. The study shows that two grains were not independent. The grain which was around the specimen sample center contained many σ phases dominated by light blue colour (43%). In other words, the prolonged heating did not give homogeneous corrosion level.

scholarly journals Long-time performance of a stainless steel crossflow filter with simulated Hanford tank waste

2015 ◽  
Vol 102 ◽  
pp. 69-79 ◽  
Author(s):  
Philip P. Schonewill ◽  
Richard C. Daniel ◽  
Rick W. Shimskey ◽  
Carolyn A. Burns ◽  
Justin M. Billing ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Time Performance ◽  
Long Time ◽  
Tank Waste

Microstructure and Properties of 304 Stainless Steel Specimen Manufactured by Cold Metal Transfer + Pulse Composite Arc Additive

2021 ◽  
Vol 13 (1) ◽  
pp. 152-160
Author(s):  
Yanjie Wang ◽  
Xuru Hou ◽  
Lin Zhao ◽  
Yun Peng ◽  
Chengyong Ma ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Additive Manufacturing ◽  
Fracture Surface ◽  
Steel Specimen ◽  
Corrosion Current ◽  
Electrochemical Analysis ◽  
304 Stainless Steel ◽  
Cold Metal Transfer ◽  
Σ Phase ◽  
Microstructure And Properties

304 stainless steel test block was fabricated by continuous melting wire with CMT and pulse mixed mode, and the path of additive manufacturing is layered slice S-shaped. The relationship between microstructure and properties of the specimen was investigated by microscope, SEM, EBSD, XRD, tensile, impact and electrochemical experiments. The results show that molding between weld and weld is very good, and the microstructure is mainly Austenite, Ferrite and a little of σ, and there are three kinds of Ferrite morphology: cellular, wormlike and lath. σ phase precipitates easily in regions with high ferrite content and is distributed at the boundary between austenite and ferrite. The specimen has good low temperature toughness. The microscopic fracture surface is mainly dimple, and the precipitates in the fracture surface are mainly fine carbide particles. The tensile strength of the additive manufacturing 304 specimen is higher than the forged specimen, and the type of fracture is ductile fracture. The electrochemical analysis of 304 stainless steel specimens and forgings shows that CMT and pulse arc additive manufacturing specimen has excellent corrosion resistance and its corrosion current is slightly lower than the forging.

Influence of Sigma Phase Precipitation on Pitting Corrosion of 2507 Super-Duplex Stainless Steel

2010 ◽  
Vol 658 ◽  
pp. 380-383 ◽  
Author(s):  
Ying Han ◽  
De Ning Zou ◽  
Wei Zhang ◽  
Jun Hui Yu ◽  
Yuan Yuan Qiao
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Ambient Temperature ◽  
Duplex Stainless Steel ◽  
Pitting Corrosion ◽  
Super Duplex Stainless Steel ◽  
Phase Precipitation ◽  
Pitting Potential ◽  
Σ Phase ◽  
Pitting Corrosion Resistance

Specimens of 2507 super-duplex stainless steel aging at 850°C for 5 min, 15 min and 60 min were investigated to evaluate the pitting corrosion resistance in 3.5% NaCl solution at 30°C and 50°C. The results are correlated with the microstructures obtained with different aging time. The precipitation of σ phase remarkably decreases the pitting corrosion resistance of the steel and the specimen aged for 60 min presents the lowest pitting potential at both 30°C and 50°C. With increasing the ambient temperature from 30°C to 50°C, the pitting potential exhibits a reduction tendency, while this tendency is less obviously in enhancing the ambient temperature than in extending the isothermal aging duration from 5 to 60 min. SEM analysis shows that the surrounding regions of σ phase are the preferable sites for the formation of corrosion pits which grew up subsequently. This may be attributed to the lower content of corrosion resistance elements in these regions formatted with σ phase precipitation.

The Effect of Aging Conditions on the Stress Relaxation Behavior of 17-7PH Stainless Steel

2021 ◽  
Vol 1016 ◽  
pp. 1664-1669
Author(s):  
Shota Yamasaki ◽  
K. Takano
Keyword(s):  
Stainless Steel ◽  
Stress Relaxation ◽  
Dislocation Density ◽  
Cold Working ◽  
Relaxation Behavior ◽  
Age Hardening ◽  
Stress Relaxation Behavior ◽  
Long Time ◽  
Aging Conditions ◽  
High Age

17-7PH stainless steel is high age-hardening property due to precipitate NiAl intermetallics by aging heat treatment after the deformation induced martensitic transformation by cold working. In this study, the effect of aging conditions on stress relaxation behavior of 17-7PH stainless steel was investigated, and the mechanism of the stress relaxation was discussed. The 0.2% proof stress after aging at 753K for 180s-18ks is about 450MPa, and then decreases after 18ks. On the other hand, the stress relaxation ratio decreases by long time aging at 753K. The dislocation density of 17-7PH decreases by long time aging at 753K. The formation of NiAl clusters around 5nm by 3D-AP analysis is observed in 17-7PH aged at 753K for 1.8ks. It is suggested that the reduction of the stress relaxation ratio after long time aging at 753K is caused by NiAl clusters and decreasing mobile dislocation density.

scholarly journals Mechanical, structural and tribological properties of superaustenitic stainless steel submitted at solution heat treatment

2015 ◽  
Vol 20 (1) ◽  
pp. 160-168 ◽  
Author(s):  
Fabiana Cristina Nascimento Borges ◽  
Willian Rafael de Oliveira ◽  
Jonas Kublitski
Keyword(s):  
Stainless Steel ◽  
Austenitic Steel ◽  
Instrumented Indentation ◽  
X Ray Diffraction ◽  
Superaustenitic Stainless Steel ◽  
Space Group ◽  
X Ray ◽  
Σ Phase ◽  
Bulk Data ◽  
Corrosive Environments

The superaustenitic stainless steel presents several technological applications, mainly in corrosive environments. The different phase precipitation might alter some of its mechanical properties. Such alterations affect several factors, including the working life of the material under adverse working conditions. In this study, Instrumented Indentation techniques, Tribology and X-ray diffraction (XRD) were used to evaluate alterations in regions close to the surface. The parameters analyzed were: hardness and elastic modulus (instrumented indentation), friction coefficient (tribology) and structural alterations of the unit cell of the identified phases (XRD - Rietveld Refinement). All properties analyzed were compared with those of common austenitic steel. The presence of σ-phase (space group P42mnm) and γ-austenite (space group Fm3m) were detected. Data analyzed indicated that the presence of σ-phase caused small alteration in properties such as hardness in regions close to the surface. In the regions farther from the surface (material bulk) data can be compared to that of conventional austenitic steel.

scholarly journals Investigating Marital Infidelity from the Perspective of Payame Noor and Azad Universities’ Students in Bileh Savar County in 2015

2017 ◽  
Vol 11 (8) ◽  
pp. 124
Author(s):  
Mohsen Alayi ◽  
Azam Faridi
Keyword(s):  
Complete Separation ◽  
Descriptive Statistics ◽  
The Past ◽  
Research Survey ◽  
Frequency Table ◽  
Marital Infidelity ◽  
Research Population ◽  
Long Time ◽  
Married Students ◽  
Research Analysis

Infidelity is one of the problems which families are involved in and it goes forward to complete separation. Of course, this problem existed long time ago, with this difference that infidelity and polygamy were common categories in families in the past and they were a privilege especially for men. Sometimes, even women themselves were looking for a wife for their husband. However, at the present time, polygamy is not considered as a privilege and value and even women are not willing to share their husband with another woman. This subject has become a problem in families. The research population consisted of students (male and female) of Payame Noor and Azad Universities in Bileh Savar County. All students of Payame Noor University were 500 and students of Azad University were 1000. Since there were no accurate statistics of married students at both universities, and also due to the lack of financial ability and high costs of research analysis, 150 students were randomly selected as the sample of research. Survey research method and questionnaire were used for data collection. Statistical methods were applied in the forms of descriptive statistics (frequency table, percent, charts) and referential statistics (Pearson test, t-test).

scholarly journals A New Approach to the Study of Multi-Pass Welds–Microstructure and Properties of Welded 20-mm-Thick Superduplex Stainless Steel

2019 ◽  
Vol 9 (6) ◽  
pp. 1050 ◽  
Author(s):  
Maria Valiente Bermejo ◽  
Kjell Hurtig ◽  
Daniel Eyzop ◽  
Leif Karlsson
Keyword(s):  
Stainless Steel ◽  
Arc Welding ◽  
Gas Metal Arc Welding ◽  
Secondary Phases ◽  
Σ Phase ◽  
Flux Cored Arc Welding ◽  
Welding Sequence ◽  
Superduplex Stainless Steel ◽  
Secondary Austenite ◽  
The Impact

Type 2507 superduplex stainless steel 20 mm in thickness was multi-pass-welded with Gas Metal Arc Welding (GMAW) and Flux-Cored Arc Welding (FCAW) processes. Recommended and higher arc energies and inter-pass temperatures were used. Thermal cycles were monitored using a recently developed procedure involving the successive instrumentation of the multi-pass welds, pass by pass, by addition of thermocouples in each weld pass. The repeatability of temperature measurements and survival rate of more than 90% of thermocouples confirmed the reliability of the procedure. Reheating by subsequent passes caused a progressive increase in the austenite content of the weld metal. The as-deposited GMAW passes with higher-than-recommended arc energy showed the lowest presence of nitrides. Therefore, the cooling rate—and not the time exposed at the critical temperature range—seems to be the key factor for nitride formation. The welding sequence layout also plays an important role in the distribution of secondary phases. A larger amount and concentration of secondary austenite and σ-phase was found for a larger number of subsequent passes in the immediate vicinity of a specific weld pass. The impact toughness exceeded requirements for all welds. Differences in absorbed energies were related to the amount of micro-inclusions found with the FCAW weld showing the lowest absorbed energies and highest amount of micro-inclusions. Pitting corrosion preferentially initiated in locations with secondary austenite and σ-phase. However, in the absence of these secondary phases, the HAZ containing nitrides was the weakest location where pitting initiated. The results of this work have implications on practical welding for superduplex stainless steels: the current recommendations on maximum arc energy should be revised for large thickness weldments, and the importance of the welding sequence layout on the formation of secondary phases should be considered.

Examination of the Orientation Relationships between the Main Phases of Duplex Stainless Steel by EBSD

2007 ◽  
Vol 537-538 ◽  
pp. 297-302
Author(s):  
Tibor Berecz ◽  
Péter János Szabó
Keyword(s):  
Stainless Steel ◽  
Duplex Stainless Steel ◽  
Stainless Steels ◽  
Electron Backscatter Diffraction ◽  
Duplex Stainless Steels ◽  
Alloying Elements ◽  
Orientation Relationships ◽  
Σ Phase ◽  
Electron Backscatter ◽  
Backscatter Diffraction

Duplex stainless steels are a famous group of the stainless steels. Duplex stainless steels consist of mainly austenitic and ferritic phases, which is resulted by high content of different alloying elements and low content of carbon. These alloying elements can effect a number of precipitations at high temperatures. The most important phase of these precipitation is the σ-phase, what cause rigidity and reduced resistance aganist the corrosion. Several orientation relationships have been determined between the austenitic, ferritic and σ-phase in duplex stainless steels. In this paper we tried to verify them by EBSD (electron backscatter diffraction).

Very-Short-Time, Very-High-Temperature Creep Rupture of Type 347 Stainless Steel and Correlation of Data

1969 ◽  
Vol 91 (1) ◽  
pp. 32-38 ◽  
Author(s):  
C. D. Lundin ◽  
A. H. Aronson ◽  
L. A. Jackman ◽  
W. R. Clough
Keyword(s):  
Stainless Steel ◽  
High Temperature ◽  
Minimum Creep Rate ◽  
Creep Rupture ◽  
Aisi Type ◽  
Data Scatter ◽  
Long Time ◽  
Short Time ◽  
Very High ◽  
Rupture Behavior

Available equipment initially developed for welding research studies was used to investigate the creep-rupture behavior of AISI type 347 stainless steel in a very-high-temperature range from 62 to 86 percent of the solidus. Stress applications from 900 to 28,000 psi gave rupture times from a fraction of a second to several hundred seconds with thousandfold variations of minimum creep rate. Results could be presented by conventional means. Data scatter on a Monkman-Grant plot was typical. Correlation and extrapolation procedures developed by Larson-Miller, Manson-Haferd, Dorn, Korchynsky, and Conrad for conventional long-time results were found to be applicable, with preference being given to the Manson-Haferd procedures.

Effect of Thermal Cycle on Microstructure and Corrosion Behavior of Duplex Stainless Steel SAF 2205 Electron Beam Welded Joint

2018 ◽  
Vol 786 ◽  
pp. 119-127
Author(s):  
Sameh M. Khafagy ◽  
Morsy Amin Morsy ◽  
H.M. El Sherbini ◽  
Y.F. Barakat
Keyword(s):  
Stainless Steel ◽  
Corrosion Resistance ◽  
Duplex Stainless Steel ◽  
Thermal Cycle ◽  
Welded Joint ◽  
Volume Fraction ◽  
Holding Time ◽  
Σ Phase ◽  
Phase Volume Fraction ◽  
Saf 2205

It is known that heat treatment (HT) highly affects the properties of base metal (BM) and fusion zones (FZ) of duplex stainless steel (DSS). In fact, it may give unwanted structure changes. Duplex stainless steels SAF 2205 welded joint was subjected to thermal cycle at temperature of 850◦C at holding times 1, 3, 5 and 7 hours. The influence of heating cycles and concentration of corrosive medium on the corrosion properties and microstructure of 2205 alloy was the objective of this work. It was found that process led to noticeable decrease in the corrosion resistance of BM and FZ specimens; moreover the decrease was large in BM than FZ. It was also found that sigma phase (σ) precipitated in the different zones of the structure. σ phase volume fraction was found to increase with increasing the holding time of HT, and its increase is larger in BM. Corrosion resistance was found to be oppositely related to σ phase formation. Secondary austenite phase (γ2) was also precipitated and its volume fraction in FZ was found to increase with increasing the holding time of HT and decreased in BM.

Sign in / Sign up

Export Citation Format

Share Document