scholarly journals Hydrogen-Induced Cracking of 500 HBW Steels Studied Using a Novel Tuning-Fork Test with Integrated Loadcell System

CORROSION ◽  
10.5006/3592 ◽  
2020 ◽  
Vol 76 (10) ◽  
pp. 954-966
Author(s):  
Renata Latypova ◽  
Oskari Seppälä ◽  
Tun Tun Nyo ◽  
Timo Kauppi ◽  
Sakari Pallaspuro ◽  
...  
Keyword(s):  
Hydrogen Embrittlement ◽  
Crack Propagation ◽  
Tuning Fork ◽  
Rolling Direction ◽  
Grain Structure ◽  
Propagation Mechanism ◽  
Cleavage Crack ◽  
Martensitic Steels ◽  
Structural Applications ◽  
Time To Fracture

Hydrogen embrittlement is a well-known problem with high-strength steels. An important aspect of hydrogen embrittlement research is the effect of the prior austenite grain (PAG) structure on hydrogen-induced fracture. The microstructural anisotropy of PAG structure depends on the steel manufacturing process. In this study, 500 HBW martensitic steels with different PAG structures are investigated with a novel tuning-fork test that utilizes an integrated loadcell system. The loadcell clamping system is used during hydrogen charging, allowing tracking of the applied force throughout the tests, which enables detection of separate phases of cracking and time-to-fracture. The elongated PAG morphology produces different results depending on the crack path direction in relation to the rolling direction, whereas the equiaxed PAG morphology does not manifest an orientation dependence. Depending on the PAG shape, also the fracture morphology differs. Time-to-fracture results show that elongated grain morphologies with transgranular quasi-cleavage crack propagation are more beneficial against hydrogen-induced fracture than equiaxed grain structure with intergranular crack propagation. These results demonstrate that the shape of the PAG structure plays an important role in the crack propagation mechanism and that it is important to consider the possible direction of hydrogen-induced cracks in the final structural applications.

A Consideration of Cleavage Crack Propagation in Fe2Si Steel

2008 ◽  
Vol 385-387 ◽  
pp. 1-4 ◽  
Author(s):  
Fabio Sorbello ◽  
Peter E.J. Flewitt ◽  
A.G. Crocker ◽  
Gillian E. Smith
Keyword(s):  
Crack Propagation ◽  
Focused Ion Beam ◽  
Process Zone ◽  
Ion Beam ◽  
Local Strain ◽  
Propagation Path ◽  
Propagation Mechanism ◽  
Cleavage Crack ◽  
Ion Milling ◽  
Bcc Structure

It is well established that within the lower-shelf temperature range of Fe2-3Si polycrystalline steels, the brittle fracture occurs predominately by transgranular cleavage, unless subject to embrittling heat-treatments. The cleavage fracture develops on the well established {001} planes of the bcc structure. In this paper we revisit the growth, of these cleavage cracks by considering crack propagation in single crystals of Fe2Si steel. Three point bend specimens manufactured from oriented crystals have been tested by impact loading at a temperature of -196°C. High spatial resolution focused ion beam imaging combined with ion milling is used to examine in detail the crack propagation path and has provided a new insight into the mechanisms involved. In particular it has been established that within the process zone of the propagating cracks local strain is accommodated by the formation of {112} twins. The results are discussed with respect to the overall crack propagation mechanism.

Mechanism of irregular crack-propagation in thermal controlled fracture of ceramics induced by microwave

2020 ◽  
Vol 21 (6) ◽  
pp. 610
Author(s):  
Xiaoliang Cheng ◽  
Chunyang Zhao ◽  
Hailong Wang ◽  
Yang Wang ◽  
Zhenlong Wang
Keyword(s):  
Crack Propagation ◽  
Industrial Application ◽  
Ceramic Materials ◽  
Advanced Technology ◽  
Analytical Models ◽  
Propagation Mechanism ◽  
Unstable Crack ◽  
Fracture Simulation ◽  
Initial Stage ◽  
Controlled Fracture

Microwave cutting glass and ceramics based on thermal controlled fracture method has gained much attention recently for its advantages in lower energy-consumption and higher efficiency than conventional processing method. However, the irregular crack-propagation is problematic in this procedure, which hinders the industrial application of this advanced technology. In this study, the irregular crack-propagation is summarized as the unstable propagation in the initial stage, the deviated propagation in the middle stage, and the non-penetrating propagation in the end segment based on experimental work. Method for predicting the unstable propagation in the initial stage has been developed by combining analytical models with thermal-fracture simulation. Experimental results show good agreement with the prediction results, and the relative deviation between them can be <5% in cutting of some ceramics. The mechanism of deviated propagation and the non-penetrating propagation have been revealed by simulation and theoretical analysis. Since this study provides effective methods to predict unstable crack-propagation in the initial stage and understand the irregular propagation mechanism in the whole crack-propagation stage in microwave cutting ceramics, it is of great significance to the industrial application of thermal controlled fracture method for cutting ceramic materials using microwave.

scholarly journals Correlation between Microstructure and Hydrogen Degradation of 690 MPa Grade Marine Engineering Steel

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 851
Author(s):  
Heng Ma ◽  
Huiyun Tian ◽  
Juncheng Xin ◽  
Zhongyu Cui
Keyword(s):  
Crack Propagation ◽  
Base Metal ◽  
Hydrogen Diffusion ◽  
Hydrogen Permeation ◽  
Steel Substrate ◽  
Phase Interface ◽  
Grain Structure ◽  
Hydrogen Degradation ◽  
Two Phase ◽  
Annealed Steel

Electrochemical H charging, hydrogen permeation, and hydrogen-induced cracking (HIC) behavior of 690 MPa grade steel substrate and different heat-treatment states (annealed, quenched, normalized, tempered) are investigated by cyclic voltammetry (CV), hydrogen permeation, electrochemical H charging, and slow strain rate tensile test (SSRT). The results show that hydrogen diffuses through the steel with the highest rate in base metal and the lowest rate in annealed steel. The hydrogen-induced cracks in base metal show obvious step shape with tiny cracks near the main crack. The cracks of annealed steel are mainly distributed along pearlite. The crack propagation of quenched steel is mainly transgranular, while the hydrogen-induced crack propagation of tempered steel is along the prior austenite grain boundary. HIC sensitivity of base metal is the lowest due to its fine homogeneous grain structure, small hydrogen diffusion coefficient, and small hydrogen diffusion rate. There are many hydrogen traps in annealed steel, such as the two-phase interface which provides accommodation sites for H atoms and increases the HIC susceptibility.

Influence of Hole Size on Crack Propagation Mechanism of Nano-Single Crystal Copper

2013 ◽  
Vol 328 ◽  
pp. 679-683
Author(s):  
Ge Li ◽  
Xian Qin Hou ◽  
Zhi Min Liu
Keyword(s):  
Molecular Dynamics ◽  
Crack Propagation ◽  
Hole Diameter ◽  
Propagation Mechanism ◽  
Hole Size ◽  
Single Crystal Copper ◽  
Dislocation Glide ◽  
Hole Position ◽  
Crack Propagation Mechanism ◽  
Dynamics Method

By molecular dynamics method, the tensile processes of nanosingle crystal copper with the crack front existence hole were simulated, and the effect of different hole size on crack propagation mechanism was analyzed. The results indicate that as the hole position remain unchanged, the hole diameter was more bigger, the atomic staggered and the crack tip deactivation were more obvious under tensile loads caused more dislocation glide appeared, meanwhile the number of slide-line was more and the trend of crack branch extend to hole position was more obvious.

Crack propagation analysis of hydrogen embrittlement based on peridynamics

2021 ◽  
Author(s):  
Xiu Ran ◽  
Songrong Qian ◽  
Ji Zhou ◽  
Zhengyun Xu
Keyword(s):  
Hydrogen Embrittlement ◽  
Crack Propagation ◽  
Propagation Analysis

scholarly journals Fatigue Crack Growth Behaviour and Role of Roughness-Induced Crack Closure in CP Ti: Stress Amplitude Dependence

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1656
Author(s):  
Mansur Ahmed ◽  
Md. Saiful Islam ◽  
Shuo Yin ◽  
Richard Coull ◽  
Dariusz Rozumek
Keyword(s):  
Fatigue Crack ◽  
Crack Propagation ◽  
Crack Growth ◽  
Crack Closure ◽  
Fatigue Cracks ◽  
Propagation Mechanism ◽  
Amplitude Dependence ◽  
Crack Growth Behaviour ◽  
Crack Propagation Mechanism ◽  
Cp Ti

This paper investigated the fatigue crack propagation mechanism of CP Ti at various stress amplitudes (175, 200, 227 MPa). One single crack at 175 MPa and three main cracks via sub-crack coalescence at 227 MPa were found to be responsible for fatigue failure. Crack deflection and crack branching that cause roughness-induced crack closure (RICC) appeared at all studied stress amplitudes; hence, RICC at various stages of crack propagation (100, 300 and 500 µm) could be quantitatively calculated. Noticeably, a lower RICC at higher stress amplitudes (227 MPa) for fatigue cracks longer than 100 µm was found than for those at 175 MPa. This caused the variation in crack growth rates in the studied conditions.

scholarly journals Analysis of Stress Corrosion Cracking Propagation of SS304 Stainless Steel Using Crack Shape and Etch Pits

2020 ◽  
Vol 58 (9) ◽  
pp. 583-589
Author(s):  
Byung Hak Choe ◽  
Sang Woo Lee ◽  
Jong Kee Ahn ◽  
Jinhee Lee
Keyword(s):  
Stainless Steel ◽  
Phase Transformation ◽  
Hydrogen Embrittlement ◽  
Crack Propagation ◽  
Stress Corrosion ◽  
High Hardness ◽  
Face Centered Cubic ◽  
High Concentration ◽  
Etch Pits ◽  
Tem Analysis

Austenitic stainless steel SS304 is vulnerable to Cl atmosphere SCC (stress corrosion crack). In this study, SCC phenomena related to stress and corrosion composition were analyzed to identify the mechanism for SCC initiation and propagation in SS304. The microstructure and mechanical properties resulting from crack propagation were analyzed by OM, SEM/EDS and micro Vickers hardness tests. The abnormal phase transformation induced by the SCC was analyzed by TEM and diffraction. As a result of these analyses, the shape of SCC was observed to form a branched type crack, which was related to etch pit patterns on the etched surface due to the austenitic fcc (face centered cubic) lattice slip. In addition, the high concentration accumulation of Cl and S components at the SCC site, observed by SEM/EDS, indicated that the SCC was affected by the corrosive atmosphere. The SCC crack propagation was accompanied by hardening, which is believed to be associated with the mechanism of hydrogen embrittlement. High resolution TEM analysis found abnormal satellite diffraction points in the SCC high hardness region. This means that a superlattice phase with high hardness values is formed near the SCC region. And the HIC (hydrogen induced crack) effect, a kind of hydrogen embrittlement, was also influenced by the hardened superlattice phase. It is assumed that the SCC and HIC are similar phenomena produced in the same stress and corrosive atmosphere by superlattice phase transformation.

Anisotropic Microstructure and Hydrogen Permeability of Nb-Ti-Ni Duplex Phase Alloy Prepared by Hot Forging-Rolling Technique

2006 ◽  
Vol 980 ◽  
Author(s):  
Sho Tokui ◽  
Kazuhiro Ishikawa ◽  
Kiyoshi Aoki
Keyword(s):  
Solid Solution ◽  
Hydrogen Embrittlement ◽  
Hydrogen Permeability ◽  
Rolling Direction ◽  
Hot Forging ◽  
The Other ◽  
Rolling Reduction ◽  
Eutectic Microstructure ◽  
Ni Alloys ◽  
Other Hand

AbstractIt has been demonstrated that the as-cast Nb40Ti30Ni30 duplex phase alloy, which consists of the primary (Nb, Ti) solid solution and the fine lamellar type eutectic {TiNi+(Nb, Ti)} phase, shows higher hydrogen permeability ¶ than that of pure Pd without the hydrogen embrittlement at 673K. In this alloy, the eutectic phase contributes to the suppression of the hydrogen embrittlement, while the primary one does mainly to the hydrogen permeation. It is important to note that even if the eutectic microstructure disappears and is replaced by the small spherical (Nb, Ti) phase embedded in the TiNi matrix by rolling and subsequent annealing, its high hydrogen permeability and large resistance to the hydrogen embrittlement are sustained. Furthermore, the present authors have observed that the primary (Nb, Ti) phase is largely elongated along the rolling direction. Consequently, it is expected that rolled and annealed Nb-Ti-Ni alloys show the large anisotropy of the microstructure and the hydrogen permeability. In the present work, the microstructure and hydrogen permeability ¶nof the Nb40Ti30Ni30 alloy after rolling and annealing treatments are examined in order to develop highly hydrogen permeable alloys utilizing the anisotropic microstructure.The primary (Nb, Ti) phase and the very fine eutectic {TiNi+(Nb, Ti)} phase are observed in the as-cast Nb40Ti30Ni30 alloy by scanning electron microscopy (SEM). The X-ray diffractometry (XRD) indicates that this alloy consists of the B2-TiNi intermetallic compounds and the bcc- (Nb, Ti) solid solution. The primary (Nb, Ti) phase is largely elongated along the rolling direction by forging and subsequent rolling at 1173 K. On the other hand, the eutectic microstructure becomes unclear with increasing the rolling reduction. The composite alloys in which the (Nb, Ti) phase is elongated along to the rolling direction are obtained by 69 % rolling reduction. ¶n of this sample is four times higher than that of as-cast one. On the other hand, ¶ for the sample vertical to the rolling direction is reduced to about one third of that of as-cast one. Thus, the hydrogen permeability of the Nb40Ti30Ni30 alloy varies about ten times or more depending on the direction of the primary¡]Nb, Ti¡^ phase. We conclude that it is possible to produce highly hydrogen permeable Nb-Ti-Ni alloys using the anisotropy of the microstructure prepared by hot forging and rolling.

scholarly journals Three Dimensional Simulation of Polycrystalline Cleavage Crack Propagation in Steel

2009 ◽  
Vol 95 (6) ◽  
pp. 498-505 ◽  
Author(s):  
Kei Sugimoto ◽  
Shuji Aihara ◽  
Yoichi Tanaka
Keyword(s):  
Crack Propagation ◽  
Three Dimensional ◽  
Cleavage Crack ◽  
Dimensional Simulation
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