scholarly journals Compound Layer Design for Deep Nitrided Gearings

Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 455
Author(s):  
Stefanie Hoja ◽  
Matthias Steinbacher ◽  
Hans-Werner Zoch
Keyword(s):  
Bulk Material ◽  
Load Capacity ◽  
Nitrided Layer ◽  
High Strength ◽  
Compound Layer ◽  
Nitride Layer ◽  
Negative Influence ◽  
Core Material ◽  
Simultaneous Formation ◽  
Short And Long Term

Deep nitriding is used to obtain a nitriding hardness depth beyond 0.6 mm. The long nitriding processes, which are necessary to reach the high nitriding hardness depths, mostly have a negative influence on the hardness and strength of the nitrided layer as well as on the bulk material. The compound layer often is considered less, because in most practical cases, it is removed mechanically after nitriding, to avoid spalling in service. However, in former investigations, it was shown, that thick and compact compound layers have the potential for high flank load capacity of gears. The investigations focus on the simultaneous formation of a high nitriding depth and a thick and compact compound layer. Beside the preservation of the strength, a challenge is to control the porosity of the compound layer, which should be as low as possible. The investigations were carried out using the common nitriding and heat treatable mild steel 31CrMoV9, which is often used for gear applications. The article gives an insight on the development of multistage nitriding processes studied by short- and long-term experiments aiming for a specific compound layer build-up with low porosity and high strength of the nitride layer and core material.

Mechanical performance of honeycomb sandwich structures built by FDM printing technique

2021 ◽  
pp. 089270572199789
Author(s):  
S Gohar ◽  
G Hussain ◽  
A Ali ◽  
H Ahmad
Keyword(s):  
Fused Deposition Modeling ◽  
Mechanical Performance ◽  
Sandwich Structures ◽  
Weight Ratio ◽  
High Strength ◽  
Core Material ◽  
Interfacial Bond Strength ◽  
Fused Deposition ◽  
Competitive Prices ◽  
Composite Face

Honey Comb Sandwich Structures (HCSS) have numerous applications in aerospace, automobile, and satellite industry because of their properties like high strength to weight ratio, stiffness and impact strength. Fused Deposition Modeling (FDM) is a process which, through its flexibility, simple processing, short manufacturing time, competitive prices and freedom of design, has an ability to enhance the functionality of HCSS. This paper investigates the mechanical behavior (i.e. flexural, edgewise compression and Interfacial bond strength) of FDM-built HCSS. The influence of face/core material was examined by manufacturing four types of specimens namely ABS core with Composite (PLA + 15% carbon fibers) face sheets, ABS core with PLA face sheets, TPU core with composite face sheets and TPU core with PLA face sheets. To measure the effect of face sheets geometry, raster layup was varied at 0°/90° and 45°/−45°. The mechanical characterization revealed that an optimum combination of materials is ABS core with composite face sheets having raster layup of 0°/90°. This study indicates that HCSS with complex lamination schemes and adequate mechanical properties could be manufactured using FDM which may widen the applications of FDM on an industrial scale.

scholarly journals Calculated research of aeroelastic stability of a bridge over the river Ob in Salekhard at the stage of assembling and operation

2019 ◽  
Vol 6 (3) ◽  
Author(s):  
Anastasiya Shustikova ◽  
Andrei Kozichev ◽  
Sergei Paryshev ◽  
Konstantin Strelkov
Keyword(s):  
Cfd Simulation ◽  
Load Capacity ◽  
Air Flow ◽  
Lift Coefficient ◽  
High Strength ◽  
Railway Bridge ◽  
Aeroelastic Stability ◽  
Ansys Fluent ◽  
Long Span ◽  
Long Span Bridge

Recently, long span bridge construction has been demanded for development of the regions of the Russian Federation. In terms of economy, it’s useful to build a combined road-railway bridge. Such bridges, generally, constitute a metal cross-cutting girder with carriageways on lower, upper or both zones of the girder. The major advantages of combined bridges are high strength and load capacity, plus cross-cutting to wind load. Focus of this research is a combined road-railway bridge over the Ob river at the stage of assembling and operation. The purpose of the study was to determine the limits of aeroelastic stability of combined road-railway bridge at the stage of assembling and operation using numerical simulation. To better understand the bridges behaviour in air flow, flow around a section model has been researched with CFD simulation in the ANSYS FLUENT. Then based on the given results of the calculations the dependence of the bridge vibrations on wind speed within a specified range is obtained, and also values of drag coefficient Сх, lift coefficient Су and torque coefficient Мz are received. These studies were carried out in the range of angles of attack α = ±3°. The possibility of divergence and galloping was also estimated. The results of the study made it possible to estimate the influence of air flow on combined bridge cross-cutting girder. Overall, the conducted research seems promising for further investigation and development in the field of bridge aeroelasticity.

scholarly journals The Assessment of Using CFRP to Enhance the Behavior of High Strength Reinforced Concrete Corbels

2021 ◽  
Vol 28 (1) ◽  
pp. 71-83
Author(s):  
Mazin Abdulrahman ◽  
Shakir Salih ◽  
Rusul Abduljabbar
Keyword(s):  
Reinforced Concrete ◽  
Ultimate Strength ◽  
Load Capacity ◽  
High Strength ◽  
Load Carrying Capacity ◽  
Test Results ◽  
Ultimate Load Capacity ◽  
Load Carrying ◽  
Externally Bonded ◽  
Effective Depth

In this research, an experimental study is conducted to investigate the behavior and strength of high strength reinforced concrete corbels externally bonded with CFRP fabric sheets and Plates with different patterns taking into account the effect of adopted variables in enhancing the ultimate strength; the effect of shear span to effective depth (a/d), configuration, type and amount of bonding. Eleven high strength reinforced corbels were cast and tested under vertical loads. Test results showed there was an improvement in the behavior and load carrying capacity of all strengthened corbels. An increasing in the ultimate strength of strengthened corbel by inclined CFRP strips reached to (92.1%) while the increasing reached to (84.21%) for using one horizontal CFRP Plates compared to un-strengthened reference specimen. Also, it can be conducted that the increase of (a/d) ratio from (0.6 to 0.8) resulted in decreasing by 21.05% in ultimate load capacity of corbels and from (0.4 to 0.6) by 31.25% and 58.69% in cracking and ultimate loads respectively Using CFRP .

Synthesis of submicrometer-grained-ultrahigh-carbon steel containing 10% aluminum by ball-milling of powders

1996 ◽  
Vol 11 (11) ◽  
pp. 2725-2730 ◽  
Author(s):  
Eric M. Taleff ◽  
Mamoru Nagao ◽  
Yoshio Ashida ◽  
Oleg D. Sherby
Keyword(s):  
Grain Size ◽  
Ball Milling ◽  
Bulk Material ◽  
Hot Isostatic Pressing ◽  
High Strength ◽  
Tensile Tests ◽  
Grain Sizes ◽  
Ultrahigh Carbon Steel ◽  
Processing Step ◽  
Size Powder

An ultrahigh-carbon (1.25 wt.%) steel alloy containing 10 wt.% aluminum (UHCS–10Al) was processed by a powder metallurgy technique. Gas-atomized powders were subjected to ball-milling in an attritor in order to obtain a submicrometer grain size. Powder material was consolidated by both hot isostatic pressing (HIP) and by hot isopressure extrusion (HIE). Bulk material with submicrometer grain sizes was produced from attrited powders. The chemical composition and microstructure of this material are characterized at each processing step, from atomization through consolidation. Tensile tests show that a high strength results from the submicrometer grain size produced in the bulk material.

Mechanical Behaviour of Gas Nitrided Ti6Al4V Bars Produced by Selective Laser Melting

2016 ◽  
Vol 704 ◽  
pp. 225-234 ◽  
Author(s):  
Peter Franz ◽  
Aamir Mukhtar ◽  
Warwick Downing ◽  
Graeme Smith ◽  
Ben Jackson
Keyword(s):  
Heat Treatment ◽  
Selective Laser Melting ◽  
Nitrided Layer ◽  
Xrd Analysis ◽  
Compound Layer ◽  
Processing Parameters ◽  
Heat Treatments ◽  
Laser Melting ◽  
Gas Nitriding ◽  
Heat Treated

Gas atomized Ti-6Al-4V (Ti64) alloy powder was used to prepare distinct designed geometries with different properties by selective laser melting (SLM). Several heat treatments were investigated to find suitable processing parameters to strengthen (specially to harden) these parts for different applications. The results showed significant differences between tabulated results for heat treated billet Ti64 and SLM produced Ti64 parts, while certain mechanical properties of SLM Ti64 parts could be improved by different heat treatments using different processing parameters. Most heat treatments performed followed the trends of a reduction in tensile strength while improving ductility compared with untreated SLM Ti64 parts.Gas nitriding [GN] (diffusion-based thermo-chemical treatment) has been combined with a selected heat treatment for interstitial hardening. Heat treatment was performed below β-transus temperature using minimum flow of nitrogen gas with a controlled low pressure. The surface of the SLM produced Ti64 parts after gas nitriding showed TiN and Ti2N phases (“compound layer”, XRD analysis) and α (N) – Ti diffusion zones as well as high values of micro-hardness as compared to untreated SLM produced Ti64 parts. The microhardness profiles on cross section of the gas nitrided SLM produced samples gave information about the i) microhardness behaviour of the material, and ii) thickness of the nitrided layer, which was investigated using energy dispersive spectroscopy (EDS) and x-ray elemental analysis. Tensile properties of the gas nitrided Ti64 bars produced by SLM under different conditions were also reported.

The Contribution of In-Line IMU Inspection to Geohazard and Crack Management Strategies

2021 ◽  
Author(s):  
Andy Young ◽  
Andrew Wilde ◽  
Ivan Grosmann
Keyword(s):  
Management Practices ◽  
Load Capacity ◽  
Management Strategies ◽  
High Strength ◽  
Ground Movement ◽  
Ground Subsidence ◽  
Measurement Unit ◽  
External Loading ◽  
Integrity Management ◽  
The Right

Abstract Geohazards and external loads are a significant threat to the integrity of pipelines in hilly terrain, at river crossings and where ground subsidence is taking place. Well designed pipelines can tolerate strains that exceed the nominal strain of 0.5% that corresponds specified minimum yield strengths, however the presence of weld defects and stress corrosion cracking can reduce the load capacity dramatically. Welds that are to specification but are under-matched on actual strength to the adjacent parent pipe have also been recognised as potentially vulnerable to low strain failures in high strength pipes. Modern pipelines in terrain susceptible to geohazards normally include design studies to identify and avoid or mitigate the threats. Surveillance of the right-of-way is also routinely carried out for pipelines with good integrity management practices, and particularly for major strategic lines. In-line inspection using an inertial measurement unit (IMU) is a well-known method to detect ground movement loads and contributes to the integrity management of pipelines. In this paper we illustrate : 1. How IMU inspection is an important tool in the management of geohazards and how it compliments other methods of geohazard assessment. 2. How locations of elevated pipe strain are identified and evaluated for external loading threats, and can be aligned with other data sets that indicate the pipeline load capacity. 3. How the locations of bending strain can be prioritised for further action. 4. How the loading profile in the pipeline can be incorporated into crack management strategies in order prioritise locations for further investigation or assessment.

Investigation of Compound Layer Structures after Nitriding and Nitrocarburizing of Quenched and Tempered Steels

2021 ◽  
Vol 76 (3) ◽  
pp. 219-236
Author(s):  
M. Sommer ◽  
S. Hoja ◽  
M. Steinbacher ◽  
R. Fechte-Heinen
Keyword(s):  
Surface Layer ◽  
Phase Composition ◽  
Bulk Material ◽  
Fatigue Behavior ◽  
Nitrogen Concentration ◽  
Maximum Level ◽  
Compound Layer ◽  
X Ray Diffraction ◽  
Treatment Processes ◽  
Layer Structures

Abstract A compound layer is formed by ingress of nitrogen from an external nitrogen source into the surface layer and the formation of nitrides when the solubility of nitrogen in the bulk material is exceeded. In the surface layer, where the nitrogen concentration is at its maximum level, the nitrides form a closed layer. The compound layer continues to contain alloy nitrides which have formed from the carbides and other precipitates from the bulk material. The properties of the compound layer have a decisive influence on the wear and fatigue behavior of the loaded surfaces. The current investigations deal with the extensive characterization of compound layers that have been produced in heat treatment processes with the aim of producing stress-resistant nitriding layers. The commonly used nitriding and quench and temper (Q&T) steels 31CrMoV9 and 42CrMo4 served as examination material. The structure of the compound layers was varied within the nitriding trials regarding the phase composition, porosity and layer thicknesses. The phase composition of the compound layers was determined by special etching, scanning electron microscopy (SEM), X-ray diffraction and GDOES.

On a possibility of replacing grey cast iron for manufacturing cast elements of electrolyzer gas collecting bell

2021 ◽  
Vol 77 (9) ◽  
pp. 1063-1070
Author(s):  
A. A. Usol’tsev ◽  
N. A. Kozyrev ◽  
S. V. Knyazev ◽  
A. I. Kutsenko ◽  
A. R. Mikhno
Keyword(s):  
Corrosion Resistance ◽  
Cast Iron ◽  
Heat Resistance ◽  
High Strength ◽  
Grey Cast Iron ◽  
Simultaneous Formation ◽  
Metal Base ◽  
Spherical Graphite ◽  
Grey Cast ◽  
Graphite Inclusions

The main process leading to the destruction of the cast elements of gas-collection bell of electrolyzer, made of grey cast iron, is the oxidation of iron by oxygen, SO2 gas and sulfur vapors to form magnetite, hematite and pyrrhotin. The simultaneous formation of iron oxides and sulfides does not prevent further corrosion, since scale is formed with a loose structure that does not have protective properties. Reducing the length of the interfacial boundaries inside the material of the cast enables to reduce the rate of corrosion destruction, which can be achieved by modifying the cast iron to change the shape of graphite inclusions, i.e. obtaining high-strength cast iron with a spherical shape of graphite inclusions. However, the obtaining spherical graphite in cast iron using magnesium modification does not exclude the access of aggressive gases to the surface of the products and the possibility of their diffusion along the grain boundaries. It was shown that alloying can be an alternative, which leads not only to the exclusion of lamellar secretions of graphite in the structure of cast iron, but also to the formation of surface oxide layers based on the alloying element preventing the corrosion. Alloying with chromium gives cast iron high abrasive resistance due to the presence of a carbide component in the structure, as well as corrosion resistance due to the alloying of the metal base, heat resistance due to increasing the electrochemical potential of the metal base and creating a strong neutral oxide film on the surface of the castings, heat resistance, etc. An experimental comparative analysis of the corrosion resistance of cast iron used for manufacturing of gas collecting bell of electrolyzers showed that chromic cast iron ЧХ3 has a higher corrosion resistance than high-strength cast iron with spherical graphite ВЧ50 and much higher than grey cast iron with lamellar graphite. However, chromic cast iron ЧХ3 has low casting properties, is very sensitive to the cooling rate and has a large heterogeneity in structure, which makes it difficult to use it for the manufacture of gas collecting bell of electrolyzers.

Ultimate Load Capacity of Spot Welds Made of Ultra High Strength Steels

2011 ◽  
Author(s):  
Zongfen Zhang ◽  
Chris Chen ◽  
Gregory Zywicki ◽  
Brad Blaski ◽  
James Blenman
Keyword(s):  
Ultimate Load ◽  
Load Capacity ◽  
High Strength Steels ◽  
High Strength ◽  
Spot Welds ◽  
Ultimate Load Capacity ◽  
Ultra High Strength Steels

scholarly journals Multilayered-Sheet Hot Stamping and Application in Electric-Power-Fitting Products

Metals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 215 ◽  
Author(s):  
Bin Zhu ◽  
Zhoujie Zhu ◽  
Yongmin Jin ◽  
Kai Wang ◽  
Yilin Wang ◽  
...  
Keyword(s):  
Contact Pressure ◽  
Load Capacity ◽  
Hot Stamping ◽  
High Strength ◽  
Optimal Number ◽  
Electrical Connection ◽  
Number Of Layers ◽  
Stamping Process ◽  
New Type ◽  
High Load Capacity

Traditional electric transmission line fittings, which are always manufactured from thick metal slabs, possess the disadvantage of heavy weight. In this study, a new type of electrical-connection-fitting, clevis-clevis component made of high-strength steel is developed to reduce weight, and a new hot-stamping process for multilayered sheets is proposed to manufacture the component efficiently. First, the structure of the new clevis-clevis component is designed, and the corresponding tool is developed. Second, a flat-tool heat transfer experiment is conducted. The influence of the number of layers and contact pressure on the cooling rate of each sheet is investigated. The optimizing number of layers and contact pressure for the multilayered-sheet, hot-stamping process are obtained. The optimal number of layers is two, and the optimal contact pressure is more than 20 MPa. The final microstructure of each sheet is fully martensitic, and the strength is about 1500 MPa. Finally, U-shaped, double-layer-sheet hot stamping is implemented to produce a typical electrical-connection-fitting, clevis-clevis component. The bearing capacity of a four-layered clevis-clevis is tested through numerical and experimental methods. The new connection-fitting clevis-clevis component exhibits a high load capacity of 280 kN. Compared with that of the traditional component, the weight of the new component is reduced by 60%.

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