Effect of Sulfur on the Hot Plasticity of GH625 Superalloy

The influences of sulfur on the hot plasticity of superalloy GH625 were studied. The results indicate that the area reduction rate were 70% between 950°C to 1250°C with the S content below 0.0020%. When the S content is higher than 0.0025%, the area reduction rate was below 50%. The fractography was examined and analyzed by scanning electric microscope (SEM). The SEM results showed that the tensile fracture was cleavage fracture with the S content above 0.0030%. There were dimples in the tensile fracture when the S content was 0.0020% and below. It is indicated that the content of sulfur has great effect on the mechanical properties of GH625. In order to improve the hot plasticity of superalloy GH625, the content of sulfur should be controlled below 20ppm.

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Evaluation of Mechanical Properties and Microstructures of Casing-Drilling Steels

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.146-147.674 ◽

2010 ◽

Vol 146-147 ◽

pp. 674-677

Author(s):

Tian Han Xu ◽

Yao Rong Feng ◽

Sheng Yin Song ◽

Zhi Hao Jin

Keyword(s):

Mechanical Properties ◽

Fracture Surface ◽

Impact Energy ◽

Cleavage Fracture ◽

Fracture Mechanism ◽

Tensile Fracture ◽

Tensile Fracture Surface ◽

Dimple Fracture ◽

Drilling Technology ◽

Casing Drilling

An investigation into the mechanical properties of K55，N80 and P110 steels was carried out for casing-drilling technology. The obvious presence of bright facets on broken K55 Charpy V-Notch (CVN) sample surfaces was indicative of the effect of microstructure on the cleavage fracture. The appearing of bright facet surfaces of K55 was attributed to the microstructure of ferrite and pearlite. The fracture surfaces of N80 and P110 CVN samples included quasi-cleavage fracture mechanism and dimple fracture mechanism, respectively. The tensile fracture surface of all three types of casing-drilling steels included dimple fracture mechanism, both the N80 and P110 specimen show higher UTS and impact energy values compared to the K55 specimen.

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Effects of CaCO3 Modificator on Microstructure and Mechanical Properties of Cast AZ91 Magnesium Alloy

Materials Science Forum ◽

10.4028/www.scientific.net/msf.546-549.155 ◽

2007 ◽

Vol 546-549 ◽

pp. 155-158

Author(s):

Qu Dong Wang ◽

Yang Zhao ◽

Qing Hua Li

Keyword(s):

Mechanical Properties ◽

Magnesium Alloy ◽

Cleavage Fracture ◽

Tensile Fracture ◽

Az91 Alloy ◽

Az91 Magnesium Alloy ◽

Microstructure And Mechanical Properties ◽

Reticular Structure ◽

Az91 Magnesium ◽

Alloy Increase

Effects of CaCO3 modificator on microstructure and mechanical properties of cast AZ91 Magnesium alloy have been investigated. Tensile fracture behavior of AZ91 alloys modified by CaCO3 has also been studied. Results show that CaCO3 modificator can obviously refine the grain of AZ91 magnesium alloy and Mg17Al12. Mg17Al12 in grain boundary of AZ91 alloy after modified by CaCO3 changes from continuous reticular structure to discontinuous reticular structure, even so much as granular structure and rod structure. After modified by 0.5wt% CaCO3 modificator, ultimate tensile strength, yield strength, impact toughness and elongation of AZ91 alloy increase from 186MPa to 200MPa, from 147MPa to 160MPa, from 4J to 9J and from 2.6% to 5%, respectively. And 0.5wt% CaCO3 modificator brings about an optimal refining effect. The study also shows that the fracture mechanism of modified AZ91 alloy is between cleavage fracture and quasi-cleavage fracture, which is as same as that of unmodified AZ91 alloy.

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Microstructure and Mechanical Properties of Cobalt Alloy Coating Deposited by Electro-Spark

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.881-883.1400 ◽

2014 ◽

Vol 881-883 ◽

pp. 1400-1404

Author(s):

Qi Feng Jing ◽

Ye Fa Tan ◽

Jian Tang ◽

Hua Tan ◽

Xiang Hong ◽

...

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Phase Composition ◽

Carbon Steel ◽

Cleavage Fracture ◽

Shear Fracture ◽

Alloy Coating ◽

Tensile Fracture ◽

Cobalt Alloy ◽

Dimple Fracture

Stellite190 cobalt alloy coating was deposited on 45 carbon steel by electro-spark deposition. Formation mechanism, microstructure, phase composition and mechanical properties of the coating were researched, fracture mechanism of the coating was analyzed. The results indicate that, the coating has dense and well distributed microstructure, mainly composed of Co, (CoCrW)6C, Cr7C3. The coating presents excellent mechanical properties with a tensile strength of 731.83 MPa, a bonding strength of 213.01 MPa and good peeling resistance. The mechanism for tensile fracture of the coating is dimple fracture, and for shear fracture is cleavage fracture.

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Studies on the Modification of Commercial Bisphenol-A-Based Epoxy Resin Using Different Multifunctional Epoxy Systems

Applied Mechanics ◽

10.3390/applmech2020023 ◽

2021 ◽

Vol 2 (2) ◽

pp. 419-430

Author(s):

Ankur Bajpai ◽

James R. Davidson ◽

Colin Robert

Keyword(s):

Mechanical Properties ◽

Glass Transition ◽

Transition Temperature ◽

Glass Transition Temperature ◽

Bisphenol A ◽

Epoxy Resin ◽

Tensile Fracture ◽

Chemical Structures ◽

Amino Phenol ◽

Epoxy Systems

The tensile fracture mechanics and thermo-mechanical properties of mixtures composed of two kinds of epoxy resins of different chemical structures and functional groups were studied. The base resin was a bi-functional epoxy resin based on diglycidyl ether of bisphenol-A (DGEBA) and the other resins were (a) distilled triglycidylether of meta-amino phenol (b) 1, 6–naphthalene di epoxy and (c) fluorene di epoxy. This research shows that a small number of multifunctional epoxy systems, both di- and tri-functional, can significantly increase tensile strength (14%) over neat DGEBA while having no negative impact on other mechanical properties including glass transition temperature and elastic modulus. In fact, when compared to unmodified DGEBA, the tri-functional epoxy shows a slight increase (5%) in glass transition temperature at 10 wt.% concentration. The enhanced crosslinking of DGEBA (90 wt.%)/distilled triglycidylether of meta-amino phenol (10 wt.%) blends may be the possible reason for the improved glass transition. Finally, the influence of strain rate, temperature and moisture were investigated for both the neat DGEBA and the best performing modified system. The neat DGEBA was steadily outperformed by its modified counterpart in every condition.

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Analysis of the Microstructure and Mechanical Properties of TiBw/Ti-6Al-4V Ti Matrix Composite Joint Fabricated Using TiCuNiZr Amorphous Brazing Filler Metal

Materials ◽

10.3390/ma14040875 ◽

2021 ◽

Vol 14 (4) ◽

pp. 875

Author(s):

Hao Tian ◽

Jianchao He ◽

Jinbao Hou ◽

Yanlong Lv

Keyword(s):

Mechanical Properties ◽

Base Metal ◽

Matrix Composite ◽

Room Temperature ◽

Filler Metal ◽

Ceramic Fiber ◽

Tensile Fracture ◽

Alloy Matrix ◽

Composite Joint ◽

Secondary Cracks

TiB crystal whiskers (TiBw) can be synthesized in situ in Ti alloy matrix through powder metallurgy for the preparation of a new type of ceramic fiber-reinforced Ti matrix composite (TMC) TiBw/Ti-6Al-4V. In the TiBw/Ti-6Al-4V TMC, the reinforced phase/matrix interface is clean and has superior comprehensive mechanical properties, but its machinability is degraded. Hence, the bonding of reliable materials is important. To further optimize the TiBw/Ti-6Al-4V brazing technology and determine the relationship between the microstructure and tensile property of the brazed joint, results demonstrate that the elements of brazing filler metal are under sufficient and uniform diffusion, the microstructure is the typical Widmanstätten structure, and fine granular compounds in β phase are observed. The average tensile strength of the brazing specimen is 998 MPa under room temperature, which is 97.3% of that of the base metal. During the high-temperature (400 °C) tensile process, a fracture occurred at the base metal of the highest tensile test specimen with strength reaching 689 MPa, and the tensile fracture involved a combination of intergranular and transgranular modes at both room temperature and 400 °C. The fracture surface has dimples, secondary cracks are generated by the fracture of TiB whiskers, and large holes form when whole TiB whiskers are removed. The proposed algorithm provides evidence for promoting the application of TiBw/Ti-6Al-4V TMCs in practical production.

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Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽

10.3390/cryst11010062 ◽

2021 ◽

Vol 11 (1) ◽

pp. 62

Author(s):

Xu Xu ◽

Zeping Zhang ◽

Wenjuan Yao

Keyword(s):

Mechanical Properties ◽

Graphene Oxide ◽

Grain Boundaries ◽

Functional Groups ◽

Oxygen Content ◽

Tensile Fracture ◽

Hydroxyl Groups ◽

Molecular Configuration ◽

Spatial Design ◽

Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

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Effect of Rare Earth on High Temperature Properties of Heat-Resisting Steel

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.557-559.108 ◽

2012 ◽

Vol 557-559 ◽

pp. 108-111

Author(s):

Xiao Liu ◽

Hu Fei Zhang

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Rare Earth ◽

High Temperature ◽

Oxidation Resistance ◽

Cleavage Fracture ◽

Oxidation Rate ◽

High Temperature Mechanical Properties ◽

Dimple Fracture ◽

Reduction Of Area

The oxidation resistance and high temperature mechanical properties of FeCrNi heat-resisting steel are analyzed and studied. The results show that the oxidation resistance of the heat-resisting steel is improved remarkably after adding RE. The value of oxidation rate of Sample 1 (without adding RE) is 1.71 times higher than Sample 2, respectively at 1423K. And the value of oxidation rate of Sample 1 is 1.4 times higher than Sample 2, respectively at 1473K. The fracture mode of heat-resisting stainless steel is typical cleavage fracture, but dimple fracture after adding RE into the steel. The high temperature mechanical properties of heat-resisting steel is improved obviously by RE. In comparison with heat-resisting stainless steel without RE, the reduction of area of heat-resisting stainless steel with RE is increased 26.27% at 1123K.

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Micro-mechanical modeling using DEM to study the effect of mechanical properties on crack propagation for snow slab avalanches

10.5194/egusphere-egu21-11482 ◽

2021 ◽

Author(s):

Bobillier Gregoire ◽

Bergfled Bastian ◽

Gaume Johan ◽

van Herwijnen Alec ◽

Schweizer Jürg

Keyword(s):

Mechanical Properties ◽

Steady State ◽

Crack Propagation ◽

Sensitivity Study ◽

Tensile Fracture ◽

Crack Speed ◽

Stress Concentrations ◽

Snow Layer ◽

Stress Regime ◽

Weak Layer

<p>Dry-snow slab avalanche release is a multi-scale process starting with the formation of localized failure in a highly porous weak snow layer below a cohesive snow slab, which can be followed by rapid crack propagation within the weak layer. Finally, a tensile fracture through the slab leads to its detachment. About 15 years ago, the propagation saw test (PST) was developed. The PST is a fracture mechanical field test that provides information on crack propagation propensity in weak snowpack layers. It has become a valuable research tool to investigate the processes involved in crack propagation. While this has led to a better understanding of the onset of crack propagation, much less is known about the ensuing propagation dynamics. Here, we use the discrete element method to numerically simulate PSTs in 3D and analyze the fracture dynamics using a micro-mechanical approach. Our DEM model reproduced the observed PST behavior extracted from experimental analysis. We developed different indicators to define the crack tip that allowed deriving crack speed. Our results show that crack propagation in level terrain reaches a stationary speed if the snow column is long enough. Moreover, we define stress concentration sections. Their length evolution during crack propagation suggests the development of a steady-state stress regime. Slab and weak layer elastic modulus, as well as weak layer shear strength, are the key input parameters for modeling crack propagation; they affect stress concentrations, crack speed, and the critical length for the onset of crack propagation. The results of our sensitivity study highlight the effect of these mechanical parameters on the emergence of a steady-state propagation regime and consequences for dry-snow slab avalanche release. Our DEM approach opens the possibility for a comprehensive study on the influence of the snowpack mechanical properties on the fundamental processes for avalanche release.</p>

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Effect of graphite and silicon carbide fillers on mechanical properties of PA6 polymer composites

Journal of Polymer Engineering ◽

10.1515/polyeng-2015-0441 ◽

2017 ◽

Vol 37 (6) ◽

pp. 547-557 ◽

Cited By ~ 5

Author(s):

Sekaran Sathees Kumar ◽

Ganesan Kanagaraj

Keyword(s):

Mechanical Properties ◽

Silicon Carbide ◽

Polymer Composites ◽

Interfacial Adhesion ◽

Hybrid Composites ◽

Fracture Morphology ◽

Tensile Fracture ◽

Injection Molded ◽

The Individual

Abstract In this paper, the combined effect of different weight percentages of silicon carbide (SiC) and graphite (Gr) reinforcement on the mechanical properties of polyamide (PA6) composite is studied. Test specimens of pure PA6, 85 wt% PA6+10 wt% SiC+5 wt% Gr and 85 wt% PA6+5 wt% SiC+10 wt% Gr are prepared using an injection molding machine. The tensile, impact, hardness, morphology and thermal properties of the injection molded composites were investigated. The obtained results showed that mechanical properties, such as tensile and impact strength and modulus of the PA6 composites, were significantly higher than the pure PA6, and hybridization with silicon carbide and graphite further enhanced the performance properties, as well as the thermal resistance of the composites. The tensile fracture morphology and the characterization of PA6 polymer composites were observed by scanning electron microscope (SEM) and Fourier transform infrared spectroscopic methods. SEM observation of the fracture surfaces showed the fine dispersion of SiC and Gr for strong interfacial adhesion between fibers and matrix. The individual and combined reinforcing effects of silicon carbide and graphite on the mechanical properties of PA6 hybrid composites were compared and interpreted in this study. Improved mechanical properties were observed by the addition of small amount of SiC and Gr concurrently reinforced with the pure PA6. Finally, thermogravimetric analysis showed that the heat resistance of the composites tended to increase with increasing silicon carbide and graphite content simultaneously.

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