scholarly journals Hydrogen Trapping Behavior in Vanadium Microalloyed TRIP-Assisted Annealed Martensitic Steel

Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 741
Author(s):  
Yang ◽  
Yu ◽  
Li
Keyword(s):  
Vanadium Carbide ◽  
Hydrogen Diffusion ◽  
Martensitic Steel ◽  
Tensile Tests ◽  
Test Results ◽  
Hydrogen Trapping ◽  
Martensitic Steels ◽  
Transformation Induced Plasticity ◽  
Hydrogen Charging ◽  
Transmission Electron

Transformation induced plasticity (TRIP)-assisted annealed martensitic (TAM) steel combines higher tensile strength and elogangtion, and has been increasingly used but appears to bemore prone to hydrogen embrittlement (HE). In this paper, the hydrogen trapping behavior and HE of TRIP-assisted annealed martensitic steels with different vanadium additions had been investigated by means of hydrogen charging and slow strain rate tensile tests (SSRT), microstructral observartion, and thermal desorption mass spectroscope (TDS). Hydrogen charging test results indicates that apparent hydrogen diffusive index Da is 1.94 × 10−7/cm2·s−1 for 0.21wt.% vanadium steel, while the value is 8.05×10−7/cm2·s−1 for V-free steel. SSRT results show that the hydrogen induced ductility loss ID is 76.2% for 0.21wt.%V steel, compared with 86.5% for V-free steel. The trapping mechanism of the steel containing different V contents is analyzed by means of TDS and Transmission electron microscope (TEM) observations. It is found out that the steel containing 0.21wt.%V can create much more traps for hydrogen trapping compared with lower V steel, which is due to vanadium carbide (VC) precipitates acting as traps capturing hydrogen atoms.The relationship between hydrogen diffusion and hydrogentrapping mechanism is discussed in details.

Hydrogen Transport in 34CrMo4 Martensitic Steel: Influence of Microstructural Defects on H Diffusion

2012 ◽  
Vol 323-325 ◽  
pp. 485-490 ◽  
Author(s):  
L. Moli-Sanchez ◽  
F. Martin ◽  
E. Leunis ◽  
J. Chêne ◽  
M. Wery
Keyword(s):  
Diffusion Coefficient ◽  
Room Temperature ◽  
Martensitic Steel ◽  
Hydrogen Trapping ◽  
Martensitic Steels ◽  
Hydrogen Diffusivity ◽  
Apparent Diffusion ◽  
Quenched Steel ◽  
Set Up ◽  
Permeation Test

The electrochemical permeation technique was used to evaluate the effect of the microstructure on hydrogen diffusivity and hydrogen trapping at room temperature in martensitic steels. A detailed study of the electrochemical permeation technique was first performed in order to identify the boundary conditions of a permeation test in the selected experimental set-up. The validity of the apparent diffusion coefficient derived from this test is also discussed. A 34CrMo4 quenched steel has been selected and designed at three tempering temperatures (200°C, 540°C and 680°C) in order to obtain three different microstructures. According to permeation measurements, H diffusion strongly depends on the microstructure. The material tempered at 540°C exhibits the smallest diffusion coefficient and the largest fraction of reversible traps at room temperature.

scholarly journals Mechanical Behaviors of Microalloyed TRIP-Assisted Annealed Martensitic Steels under Hydrogen Charging

Materials ◽  
2021 ◽  
Vol 14 (24) ◽  
pp. 7752
Author(s):  
Xiongfei Yang ◽  
Hao Yu ◽  
Chenghao Song ◽  
Lili Li
Keyword(s):  
Tensile Strength ◽  
Volume Fraction ◽  
Hydrogen Desorption ◽  
Total Elongation ◽  
Microalloyed Steels ◽  
Steel Matrix ◽  
Hydrogen Trapping ◽  
Martensitic Steels ◽  
Hydrogen Charging ◽  
Trapping Effect

Transformation Induced Plasticity (TRIP)-assisted annealed martensitic (TAM) steel sheets with various microalloying additions such as niobium, vanadium, or titanium were prepared on laboratory scale and subjected to a double-quenching and austempering heat treatment cycle. Slow strain rate tensile (SSRT) was tested on the investigated TAM steels with and without hydrogen charging to reveal their tensile behaviors and hydrogen induced embrittlement effects. Microstructure observations by scanning electron microscope (SEM) are composed of a principal annealed martensitic matrix and 11.0–13.0% volume fraction of retained austenite, depending on the type of microalloying addition in the different steels. SSRT results show that these TRIP-assisted annealed martensitic steels under air media conditions combine high tensile strength (>1000 MPa) and good ductility (~25%), while under hydrogen charging condition, both tensile strength and ductility decrease where tensile strength ranges between 680 and 760 MPa, down from 1000–1100 MPa, and ductility loss ratio is between 78.8% and 91.1%, along with a total elongation of less than 5%. Hydrogen charged into steel matrix leads to the appearance of cleavage fractures, implying the occurrence of hydrogen induced embrittlement effect in TAM steels. Thermal hydrogen desorption results show that there are double-peak hydrogen desorption temperature ranges for these microalloyed steels, where the first peak corresponds to a high-density dislocation trapping effect, and the second peak corresponds to a hydrogen trapping effect exerted by microalloying precipitates. Thermal desorption analysis (TDS) in combination with SSRT results demonstrate that microalloying precipitates act as irreversible traps to fix hydrogen and, thus, retard diffusive hydrogen motion towards defects, such as grain boundaries and dislocations in microstructure matrix, and eventually reduce the hydrogen induced embrittlement tendency.

Microstructure and Mechanical Properties of n-Irradiated Fe-Cr Model Alloys

2006 ◽  
Vol 981 ◽  
Author(s):  
Milena Matijasevic ◽  
Abderrahim Al Mazouzi
Keyword(s):  
Mechanical Stability ◽  
Tensile Tests ◽  
High Energy ◽  
Mechanical Tests ◽  
Test Results ◽  
Martensitic Steels ◽  
Irradiation Hardening ◽  
Cr Concentration ◽  
Accelerator Driven Systems

AbstractHigh chromium ( 9-12 wt %) ferritic/martensitic steels are candidate structural materials for future fusion reactors and other advanced systems such as accelerator driven systems ADS). Their use for these applications requires a careful assessment of their mechanical stability under high energy neutron irradiation and in aggressive environments. In particular, the Cr concentration has been shown to be a key parameter to be optimized in order to guarantee the best corrosion and swelling resistance, together with the least embrittlement.In this work, the characterization of the neutron irradiated Fe-Cr model alloys with different Cr % with respect to microstructure and mechanical tests will be presented. The behavior of Fe-Cr alloys have been studied using tensile tests at different temperature range ( from -160°C to 300°C). Irradiation-induced microstructure changes have been studied by TEM for two different irradiation doses at 300°. The density and the size distribution of the defects induced have been determined. The tensile test results indicate that Cr content affects the hardening behavior of Fe-Cr binary alloys. Hardening mechanisms are discussed in terms of Orowan type of approach by correlating TEM data to the measured irradiation hardening.

Role of Mo/V carbides in hydrogen embrittlement of tempered martensitic steel

2015 ◽  
Vol 33 (6) ◽  
pp. 433-441 ◽  
Author(s):  
Junmo Lee ◽  
Taekyung Lee ◽  
Young Jin Kwon ◽  
Dong-Jun Mun ◽  
Jang-Yong Yoo ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Hydrogen Embrittlement ◽  
Beneficial Effect ◽  
Mechanical Performance ◽  
Martensitic Steel ◽  
Carbide Precipitation ◽  
Hydrogen Trapping ◽  
Martensitic Steels ◽  
Cr Addition

AbstractThe vulnerability of tempered martensitic steel to hydrogen embrittlement (HE) has attracted attention from a number of researchers. Although utilizing carbide precipitation is one of effective methods to improve HE resistance, few studies have focused on the effects of carbide characteristics, such as the chemical composition and morphology of carbide. This work clarifies the role of Mo carbide and V carbide in the HE behavior of tempered martensitic steels with four steels whose chemical composition was carefully controlled. The beneficial effect of carbides is discussed in terms of hydrogen trapping and fracture mode. The low amount of trapped hydrogen and undissolved carbide led to excellent HE resistance of Mo carbides compared to V carbides. In addition, the superior mechanical performance of Cr-Mo steel was also interpreted by the effect of Cr addition as well as Mo carbides.

Research on the Microstructure and Mechanical Properties of Spray-Deposited 8009 Heat Resistant Aluminum Alloy

2014 ◽  
Vol 543-547 ◽  
pp. 3733-3736
Author(s):  
Rong Hua Zhang ◽  
Biao Wu ◽  
Xiao Ping Zheng
Keyword(s):  
Mechanical Properties ◽  
Aluminum Alloy ◽  
Tensile Tests ◽  
Test Results ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Resistant ◽  
Microstructure And Mechanical Properties ◽  
Transmission Electron

In this study, 8009 heat resistant aluminum alloy was synthesized by the spray atomization and deposition technique. The microstructure and mechanical properties of the alloy were studied using transmission electron microscopy, X-ray diffraction, and tensile tests. The secondary phases in the microstructure of the spray-deposited alloy were examined. The tensile test results indicate that the spray-deposited 8009 alloy both at room and elevated temperature displays superior tensile strength due to the presence of the thermally stable Al12(Fe,V)3Si particles.

Effects of Thermal Exposure on the Mechanical Properties and Microstructure Stability of an Al-Cu-Mg-Ag Alloy

2012 ◽  
Vol 554-556 ◽  
pp. 671-681
Author(s):  
Sheng Yin Song ◽  
De Li Gao ◽  
Chun Feng ◽  
Zhi Yi Liu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Exposure Time ◽  
Thermal Exposure ◽  
Tensile Tests ◽  
Test Results ◽  
Strengthening Phase ◽  
Ω Phase ◽  
Microstructure Stability ◽  
Transmission Electron

Mechanical properties and microstructural evolution of an Al-Cu-Mg-Ag alloy during thermal exposure at elevated temperature were characterized by means of tensile tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The tensile test results suggested that tensile strength ( ) and yield strength ( ) reduced with both increasing exposure time and temperature. Correspondingly elongation of samples increased steadily with increasing exposure time and temperature, which resulted in ductile fracture. TEM results suggested the reduction of mechanical property of samples was attributed to coarsening and reduction in amount of dominant strengthening phase-Ω phase during thermal exposure.

Effects of Thermal Exposure on the Mechanical Properties and Microstructure Stability of an Al-Cu-Mg-Ag Alloy

2010 ◽  
Vol 97-101 ◽  
pp. 675-678
Author(s):  
An Jing Duan ◽  
Zhi Yi Liu ◽  
Li Fang Gao
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Thermal Exposure ◽  
Tensile Tests ◽  
Transgranular Fracture ◽  
Test Results ◽  
Ω Phase ◽  
Microstructure Stability ◽  
Transmission Electron ◽  
Thermal Stability Of

Mechanical properties and microstructural evolution of an Al-Cu-Mg-Ag alloy during thermal exposure at elevated temperature were characterized by means of tensile tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observation. The tensile test results suggested that tensile strength (σBbB) and yield strength (σBsB) reduced with both increasing exposure time and temperature. When exposed at 150°C, the Al-Cu-Mg-Ag alloy exhibits good structural stability due to the splendid thermal stability of the Ω phase. SEM results showed that the specimen was fractured in a combined manner of intergranular and transgranular fracture. TEM results suggested the reduction of mechanical properties of samples was attributed to the coarsening of Ω phase and the precipitation of θ phase during thermal exposure.

Analysis of temperature and strain rate dependencies of softening regime for tempered martensitic steel

2017 ◽  
Vol 52 (4) ◽  
pp. 226-238 ◽  
Author(s):  
Johanna Eisenträger ◽  
Konstantin Naumenko ◽  
Holm Altenbach ◽  
Elisabetta Gariboldi
Keyword(s):  
Strain Rate ◽  
Mechanical Behaviour ◽  
Elevated Temperatures ◽  
Martensitic Steel ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Test Results ◽  
Strain Localisation ◽  
Surface Measurements ◽  
Softening Stage

This article aims to analyse the influence of temperature and strain rate on the mechanical behaviour of the high-chromium martensitic steel X20CrMoV12-1. The analysis is based on two series of high-temperature uniaxial tensile tests. In a first series, the tensile tests are conducted until rupture, and temperature as well as strain rate are varied systematically. The corresponding stress–strain curves show an extended softening stage. In order to examine softening, it is crucial to distinguish between microstructural changes and strain localisation due to necking. For this reason, a tensile test at low strain rate is performed several times, while the test is terminated at different strain levels in order to examine the onset of necking. Based on the test results and surface measurements of the deformed specimens, the strain level at which necking starts is determined, and possible interactions between softening and necking are discussed. The tensile tests have been conducted in order to calibrate a mechanical model which supplies reliable predictions on the material behaviour under different loading scenarios at elevated temperatures. For this reason, a framework based on microstructural processes is presented in the second part of the article. The model applies a binary mixture approach in conjunction with an iso-strain concept. Furthermore, backstress and softening variables are introduced to consider hardening and softening effects. This procedure results in a system of three differential equations describing the mechanical behaviour.

Microstructural Characteristics and Mechanical Properties of Spray-Deposited Mg-Gd-Y-Zr Alloy

2014 ◽  
Vol 783-786 ◽  
pp. 503-508
Author(s):  
Feng Wang ◽  
Bai Qing Xiong ◽  
Yon Gan Zhang ◽  
Zhi Hui Li ◽  
Hong Wei Liu ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Scanning Transmission Electron Microscopy ◽  
Tensile Tests ◽  
Test Results ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Strengthening Phases ◽  
Zr Alloy

In this study, Mg-6.8Gd-4.5Y-0.5Zr alloy was fabricated by the spray atomization and deposition technique. The microstructure and mechanical properties of the alloy were studied using optical microscopy, scanning/transmission electron microscopy, X-ray diffraction, and tensile tests. The secondary phases in the microstructure of the spray-deposited alloy were examined. The tensile test results indicate that the spray-deposited Mg-6.8Gd-4.5Y-0.5Zr alloy displays superior tensile strength due to grain refinement and the presence of precipitating strengthening phases.

Effects of Thermal Exposure on Mechanical Properties of Al-4.87Cu-1.2Mg-1.0Ag Alloy

2011 ◽  
Vol 189-193 ◽  
pp. 1031-1035
Author(s):  
An Jing Duan ◽  
Wei Jiang ◽  
Yao Hui Ou ◽  
Jian Jun Qin ◽  
Zhi Yi Liu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
Thermal Exposure ◽  
Tensile Tests ◽  
Transgranular Fracture ◽  
Test Results ◽  
Excellent Thermal Stability ◽  
Ω Phase ◽  
Transmission Electron ◽  
Thermal Stability Of

Mechanical properties and microstructural evolution of an Al-Cu-Mg-Ag alloy during thermal exposure at elevated temperature were characterized by means of tensile tests, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observation. The tensile test results suggested that tensile strength (σb) and yield strength (σs) reduced with both increasing exposure time and temperature. When exposed at 150°C, the Al-4.87Cu-1.2Mg-1.0Ag alloy exhibits good structural stability due to the excellent thermal stability of the Ω phase. SEM results showed that the specimen was fractured in a combined manner of intergranular and transgranular fracture. TEM results suggested the reduction of mechanical properties of samples was attributed to the coarsening of Ω phase and the precipitation of S' phase during thermal exposure.

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