Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
- 2019 (40) (entfernen)
Dokumenttyp
Sprache
- Englisch (40)
Referierte Publikation
- ja (40) (entfernen)
Schlagworte
- Laser beam welding (5)
- Friction (4)
- Wear (4)
- Hydrogen (3)
- 3D printing (2)
- Additive manufacturing (2)
- Dual phase steel (2)
- High power laser beam welding (2)
- High-strength steels (2)
- Hydrogen assisted cracking (2)
- Laser implantation (2)
- Martensite (2)
- Multiple cracks (2)
- Non-metallic inclusions (2)
- Pores (2)
- Resistance spot welding (2)
- TiB2 (2)
- 3D Druck (1)
- AISI 304L (1)
- AISI 321 stainless steel (1)
- AISI D2 (1)
- Abrasion (1)
- Additive Fertigung (1)
- Additive Manufacturing (1)
- Adsorption (1)
- Advanced high strength steel (1)
- Advanced high strength steels (1)
- Biopolymers (1)
- Boundary element method (1)
- Bulging effect (1)
- Carbide (1)
- Carrier gas hot extraction (1)
- Characterisation (1)
- Characterization (1)
- Chunky graphite (1)
- Circumferential weld (1)
- Coarse-grained heat-affected zone (1)
- Composites (1)
- Contact fatigue (1)
- Corrosion pits (1)
- Crack (1)
- Crack arrest (1)
- Cracking (1)
- Critical strain (1)
- Defects (1)
- Deposition welding (1)
- Deuterium (1)
- Direct energy deposition (1)
- Dissimilar metal weld overlays (1)
- Ductile iron (1)
- Editorial Board (1)
- Electro-thermomechnical model (1)
- Electrode geometry (1)
- Electromagnetic stirring (1)
- Element transport (1)
- Ellipsometry (1)
- End crater (1)
- Engine oil design (1)
- Engine oil testing (1)
- Environment (1)
- Experimental design (1)
- Fatigue (1)
- Fatigue crack propagation (1)
- Fatigue crack propagation stages (1)
- Fatigue strength (1)
- Fatigue strength and life (1)
- Ferritic spheroidal graphite cast iron (1)
- Finite element method (1)
- Formation (1)
- Fracture mechanics (1)
- Full penetration (1)
- Fusion zone (1)
- GMA welding (1)
- GMAW (1)
- Grain size (1)
- Grain structure (1)
- Graphite modules (1)
- Hardmetal (1)
- Heat conduction (1)
- Heat control (1)
- Heat treatment (1)
- Highspeed-plasma-laser-cladding (1)
- Hot crack (1)
- Hot cracking (1)
- Hot steam (1)
- Hot-Stamping (1)
- Hybrid laser-arc welding (1)
- Hydrogen assisted stress corrosion cracking (1)
- Hydrogen dependent mechanical properties (1)
- Hydrogen-containing hot gas (1)
- Hydrophobin (1)
- Impact damage (1)
- In-situ Process Monitoring (1)
- Inclusion cluster (1)
- Inclusion size (1)
- Inconel 718 (1)
- Initial crack size (1)
- Intergranular cracking (1)
- Journal (1)
- LME (1)
- Laser Metal Deposition (1)
- Laser Powder Bed Fusion (1)
- Laser Pulver Auftragsschweißen (1)
- Laser beam melting (1)
- Laser dispersing (1)
- Laser welding (1)
- Liquid metal embrittlement (1)
- Low heat input GMA welding (1)
- MHD (1)
- Magnetohydrodynamics (1)
- Material defects (1)
- Mechanical properties (1)
- Mechanical property (1)
- Micro-shrinkages (1)
- Microstructure (1)
- Mis-match (1)
- Modeling (1)
- Neutron imaging (1)
- NiCrBSi (1)
- Nickel alloys (1)
- Niobium alloying (1)
- Non-destructive Materials (1)
- Numerical analysis (1)
- Numerical simulation (1)
- Optical measurment technique (1)
- Oscillating magnetic field (1)
- PEAK (1)
- Parabolic flight (1)
- Prevention (1)
- Process development (1)
- Process parameters (1)
- Process simulation (1)
- Properties (1)
- RSW (1)
- Raman spectroscopy (1)
- Residual stresses (1)
- Restraint (1)
- Safety (1)
- Scratches (1)
- Selective Laser Melting (1)
- Shrinkages (1)
- Solidification (1)
- Standardisation (1)
- Statistics (1)
- Sub-oxide (1)
- Surface roughness (1)
- Surface texturing (1)
- Testing method (1)
- Thermal conductivity device (1)
- Thermo-fluid dynamics (1)
- Thermo-fluid flow (1)
- Thermografie (1)
- Thermography (1)
- Thick materials (1)
- ToF-SIMS (1)
- Tribofilm (1)
- Tungsten carbide (1)
- UHMWPE (1)
- Ultra-high strength steel (1)
- Vacuum (1)
- Wear resistance (1)
- Weld pool behavior (1)
- Welding process simulation (1)
- X38CrMoV5-3 (1)
- Year in Review (1)
- Zinc coated steel (1)
- Zirconia (1)
- arbidic austempered ductile iron (1)
- digital image correlation (1)
- dual phase steel (1)
- resistance spot welding (1)
- µ-gravity (1)
Organisationseinheit der BAM
- 9 Komponentensicherheit (40) (entfernen)
Automotive engine lubricants
(2019)
In 2003, ASTM Manual 37, Fuels and Lubricants Handbook: Technology, Properties, Performance and Testing, featured a chapter discussing automotive lubricants, including engine oils, automatic transmission fluids, manual transmission fluids, gear lubricants, and greases. This chapter, by Schwartz, Tung, and McMillan, surveyed all of these classes of lubricants, up to its publication in 2003.
More recently, the period between 2003 and 2010 has been addressed as part of a book copublished by ASTM and SAE International (coeditors Simon Tung and George Totten), where Fox surveyed the development of engine oil specifications that emerged during those years.
This chapter surveys the evolution of engine oil design and testing since 2002 and concludes with insights into future directions offered by recent tribological research. Our objective is to provide a reader new to the field with an understanding of the following:
- Engine oil composition and formulation
- North American engine oil specification development, and an outline of emergent European specifications
- How emergent specifications and legislative requirements are linked to the introduction of new engine hardware
- How tribological innovation can contribute to future enhancements in engine efficiency
In parallel, we will provide several tables comparing groups of contemporaneous specifications.
Carbidic Austempered Ductile Iron (CADI) microstructures containing eutectic carbides can be produced by the addition of carbide stabilizing elements, such as chromium. Carbides formed from the addition of Cr are eutectic of M3C type. The presence of such hard phases can enhance the abrasion wear resistance of ductile iron. A new CADI can be produced by the addition of Nb. Niobium carbide particles are formed in the beginning of solidification and remain stable once they are insoluble in solid iron matrix. The dry sand abrasive wear resistance of ductile irons alloyed with 1.0, 1.8, and 2.4 wt% Nb were tested in both “as-cast” and “heat treated” conditions using standard ASTM G65. Results were compared to abrasive wear data obtained on ductile iron alloyed with 1 wt% Cr, CADI (1 wt% Cr), and the basic composition of iron without carbide stabilizing elements. In the “ascast” condition, the addition of Nb did not lead to a reduction in wear, while CADI with Nb is a promising substitute for CADI with Cr addition, because both materials showed very similar values of abrasion resistance.
Micro-ploughing and micro-cutting mechanisms were observed on the worn surfaces of ductile irons. Abrasive wear resistance of these alloys was correlated with the volume fraction of carbides.
The present work deals with the development of a strategy for the prevention of end crater defects in high-power laser welding of thick-walled circumferential welds. A series of experiments were performed to understand the influence of the welding Parameters on the formation of end crater defects such as pores, cracks, root excess weld metal and shrinkage cavities in the overlap area. An abrupt switch-off of the laser power while closing the circumferential weld leads to a formation of a hole which passes through the whole welded material thickness. A laser power ramp-down causes solidification cracks which are initiated on the transition from full-penetration mode to partial penetration. Defocusing the laser beam led to promising results in terms of avoiding end crater defects. Cracks and pores in the overlap area could be effectively avoided by using defocusing techniques.
A strategy for avoiding of end crater imperfections was tested on flat specimens of steel grade S355J2 with a wall thickness of between 8 mm and 10 mm and then transferred on the 10 mm thick pipe sections made of high-strength pipeline steel API5L-X100Q.
Among the various welding technologies, resistance spot welding (RSW) and laser beam welding (LBW) play a significant role as joining methods for the automobile industry. The application of RSW and LBW for the automotive body alters the microstructure in the welded areas. It is necessary to identify the mechanical properties of the welded material to be able to make a reliable statement about the material behavior and the strength of welded components. This study develops a method by which to determine the mechanical properties for the weldment of RSW and LBW for two dual phase (DP) steels, DP600 and DP1000, which are commonly used for the automotive bodies. The mechanical properties of the resistance spot weldment were obtained by performing tensile tests on the notched tensile specimen to cause an elongation of the notched and welded area in order to investigate its properties. In order to determine the mechanical properties of the laser beam weldment, indentation tests were performed on the welded material to calculate its force-penetration depth-curve. Inverse numerical simulation was used to simulate the indentation tests to determine and verify the parameters of a nonlinear isotropic material model for the weldment of LBW. Furthermore, using this method, the parameters for the material model of RSW were verified. The material parameters and microstructure of the weldment of RSW and LBW are compared and discussed. The results show that the novel method introduced in this work is a valid approach to determine the mechanical properties of welded high-strength steel structures. In addition, it can be seen that LBW and RSW lead to a reduction in ductility and an increase in the amount of yield and tensile strength of both DP600 and DP1000.
Ferritic spheroidal graphite cast iron (SGI) materials have a remarkable technical poten-tial and economic impact in modern industry. These features are closely related to the question of how the cast materials can be produced without structural defects and graphite degenerations such as for example chunky graphite. Although the chunky graphite degeneration superficially seems to be well known, its metallurgical background is still controversially discussed, appropriate field-tested non-destructive tools for its quantification in castings are lacking and the knowledge on its impact on material properties is fairly limited. Addressing this status, the article is providing a current overview on the subject. Existing theories on formation and growth mechanisms of chunky graphite are briefly reviewed. Furthermore, from a metallurgical point of view, causes for the appearance of chunky graphite as well as preventive measures are concisely summarized. Particular attention is paid to the morphology of chunky graphite and how it can be characterized by destructive and non-destructive techniques. Special emphasis was laid on providing a comprehensive overview on the impact of chunky graphite on strength, ductility, fatigue limit, fatigue crack growth rate as well as fracture tough-ness of ferritic SGI materials based on experimental data. Moreover, conclusions for the assessment of castings affected by chunky graphite are drawn.
Advanced high strength steels are usually coated by a zinc layer for an increased resistance against corrosion. During the resistance spot welding of zinc coated steel grades, liquid metal embrittlement (LME)mayoccur. As a result, cracking inside and around the spot weld indentation is observable. The extent of LME cracks is influenced by a variety of different factors. In this study, the impact of the used electrode geometry is investigated over a stepwise varied weld time.
A spot welding finite element simulation is used to analyse and explain the observed effects. Results show significant differences especially for highly increased weld times. Based on identical overall dimensions, electrode geometries with a larger working plane allow for longer weld times, while still preventing LME within the investigated material and maintaining accessibility.
The laser implantation–named technique aims to address the tribological problems frequently seen on tool surfaces during hot stamping. It is based on the creation of elevated dome- or ring-shaped hard structures on the surface of tool steels by a localized dispersing of hard particles. Therefore, a combination of the two distinct approaches that are normally used in surface Technology for optimizing friction and wear, i.e., surface texturing and surface material optimization, are realized in one processing step. In experimental studies, a localized dispersing of TiB2 particles in the surface layer of the hot work tool steel X38CrMoV5-3 was considered and compared with punctual laser–remelted textures. The structures (micro-) hardness was measured at top- and cross-sections. With the aid of a scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction the interaction between the hard particles and the substrate material were studied. From the results, an optimal parameter range was identified for laser implantation. To the investigation’s end, the implant geometry was measured by optical microscopy and White light microscopy. Furthermore, a mathematic model was introduced, which allows a prediction of the implant geometry as a response to the laser parameters. It was shown that the implantation of TiB2 particles leads to a significant hardness increase up to 1600 HV1 due to the dispersion of initial particles and an in situ precipitation of new titanium-rich phases. It was possible to create defect-free dome- and ring-shaped microstructures on the surfaces. It was also shown that the implants geometry highly depends on the applied laser parameters. The applied central composite design shows a good agreement with the experimental results.
In the present work it was shown that the tribologcal profiles of special model oxides under dry unidirectional sliding have shown, that sub-oxides have a contribution to the tribological behavior of carbides and cermets, when they are tribo-oxidatively formed, because their tribological profiles as monolithic materials are homologous in part or totally, or compete with hardmetals or cermets, depending from the operating conditions regarded.