Steels for bearings

The mechanical properties of ex-situ and in-situ metallic glass matrix composites (MGMCs) have proven to be both scientifically unique and of potentially important for practical applications. However, the underlying deformation mechanisms remain to be studied. In this article, we review the development, fabrication, microstructures, and properties of MGMCs, including the room-temperature, cryogenic-temperature, and high-temperature mechanical properties upon quasi-static and dynamic loadings. In parallel, the deformation mechanisms are experimentally and theoretically explored. Moreover, the fatigue, corrosion, and wear behaviors of MGMCs are discussed. Finally, the potential applications and important unresolved issues are identified and discussed.

/pdf/metallic-glass-matrix-composites-4gwn3l3aoz.pdf

Metallic glass matrix composites

https://docs.lib.purdue.edu/cgi/viewcontent.cgi?article=2056&context=nanopub

Fatigue Performance Improvement in AISI 4140 Steel by Dynamic Strain Aging and Dynamic Precipitation During Warm Laser Shock Peening

Bulk metallic glasses (BMGs) can exhibit excellent combinations of strength and fracture toughness that cannot be achieved by traditional metals, making them attractive for load bearing, mechanical engineering applications. Furthermore, recent research on BMGs has shown that many early perceived shortcomings, such as apparent brittleness or poor fatigue resistance, are not as big of a problem as once thought. The purpose of this paper is to review some of the unique mechanical characteristics of BMGs along with some of the strategies that may be used to improve or exploit their characteristics so that BMGs may be used as structural materials in engineering applications.

Bulk Metallic Glasses as Structural Materials: A Review

Direct Z-scheme anatase/rutile bi-phase nanocomposite TiO 2 nanofiber photocatalyst with enhanced photocatalytic H 2 -production activity

The work investigates the cyclic fatigue behavior of alumina. It reveals that for cyclic torsion tests the maximum stress criterion is not valid. Cyclic torsion loading leads to a reduced lifetime compared to cyclic tensile-compression. Also an increased cyclic fatigue effect compared to four point bending tests was revealed.

Fatigue of Alumina Under Cyclic Torsion Loading

For an increase in safety against crack initiation and growth in metallic structures of airplanes different concepts were developed in the past. In the focus of this work are profiles made of continuously reinforced extruded aluminum. The production and the used die set of these profiles is presented as well as problems occurring in terms of geometrical inaccuracies of the embedded high strength wires. In addition, this paper attends to the problem of lateral seam weld formation. The interface between the AA-2099 as well as AA-6056 aluminum alloy and the high strength wires Nivaflex and Nanoflex were characterized by metallurgic investigations and push-out tests. As a result it can be stated that a sufficient geometrical accuracy could be achieved and a high interface strength can be accomplished even if a slight gap is still present in the interface layer between matrix and reinforcing element.

/pdf/prototype-manufacturing-of-extruded-aluminum-aircraft-3ft5sdrfl4.pdf

Prototype Manufacturing of Extruded Aluminum Aircraft Stringer Profiles with Continuous Reinforcement

In the field of lightweight construction for transportation means, hybrid structures composed of high-strength and low-density materials exhibit a high potential for application. The composite extrusion process allows an easy embedding of metallic reinforcements into a multitude of light metal alloys. The current work shows that different metallic wire reinforced light alloys with a content of 11.1 vol% lead to a significant increase in lifetime of different aluminum and magnesium alloys under fully reversed stress controlled fatigue loading. Based on the knowledge of the quasi-static behavior of the single components and the fatigue behavior of the matrix material, a new lifetime model is used to predict the lifetime for different unidirectionally reinforced material systems.

Fatigue Behavior and Lifetime Prediction of Unidirectionally Wire Reinforced Lightweight Metal Matrix Composites

Rissausbreitungsverhalten in hochfesten Stählen

A possibility to increase both stiffness and strength of aluminium-based structures for the application in lightweight profiles for vehicle space frames is the use of composite extrusions in which high-strength metallic reinforcements are incorporated. Within the scope of the present investigations, composite-extruded profiles with wire-reinforcements made of austenitic spring steel 1.4310 (X10CrNi18-8), in an aluminium matrix AA6060 (AlMgSi0.5), which were exposed to different corrosive media for different times, were characterised in terms of the debonding shear strength using the push-out-technique. The formation of a galvanic couple could be conceived mathematically in regard of terms describing the formation of a shear-impeding layer and the corrosive attack. Thereby the parameters for the different media could be determined.

/pdf/documentation-of-the-corrosion-of-composite-extruded-5c3035maez.pdf

Eberhard Kerscher

Papers

Fatigue of Alumina Under Cyclic Torsion Loading

Prototype Manufacturing of Extruded Aluminum Aircraft Stringer Profiles with Continuous Reinforcement

Fatigue Behavior and Lifetime Prediction of Unidirectionally Wire Reinforced Lightweight Metal Matrix Composites

Rissausbreitungsverhalten in hochfesten Stählen

Documentation of the Corrosion of Composite-Extruded Aluminium Matrix Extrusions using the Push-Out Test