Heinz Werner Höppel

• PD Dr.-Ing.
• Friedrich-Alexander-University Erlangen-Nürnberg

Cu/Nb laminated metallic composites (LMCs) exhibit extraordinary mechanical strength while electrical conductivity is maintained at a high level. In this research, Cu‐based LMCs with varying volume fraction of niobium are produced via accumulative roll bonding (ARB) and additionally cold‐rolled and heat‐treated to identify the role of these heterog...

Herein, the influence of one‐ and two‐step preageing treatments prior to the artificial ageing step to peak age condition for three different 6xxx alloys, from low to high alloy content, is investigated. Analysis of the preaged conditions using atom probe tomography (APT) reveals a broad distribution of Mg and Si clusters, with some instances of Gu...

Copper alloys containing chromium and hafnium combine elevated mechanical strength and high electrical and thermal conductivity. For the simultaneous enhancement of both material properties, precipitation hardening is the utilized mechanism. Therefore, the aim is to analyze the influence of chromium and hafnium in binary and ternary low-alloyed cop...

Investigations on microstructure and texture development during processing of Al–Mg–Si sheet and extrusion profiles focused on describing and modelling the changes in the bulk. However, understanding the evolution of microstructure in the sub-surface region is highly relevant, as this governs material performance under corrosion and bending deforma...

Heterostructured materials such as metallic laminates (LMCs) can be specifically tailored to showcase significantly increased mechanical behavior based on the hetero-deformation-induced (HDI) strengthening effect caused by the co-deformation at the vicinity of interfaces. This study introduces a new approach to quantify these co-deformation effects...

The capability of wire and arc additive manufacturing (WAAM) to produce large, near-net-shaped parts with inexpensive equipment has led to the process being considered as one of the options to significantly decrease the buy-to-fly ratio in aircraft manufacture. Even so, there are several challenges associated with the process: achieving mechanical...

In the present study, fatigue crack growth (FCG) in a laminated metal composite (LMC) consisting of Al-based constituents with dissimilar strength was studied. Additionally, the FCG in both monolithic constituent materials was determined and a linear elastic rule of mixture (ROM) concept was calculated as a reference for the FCG of the laminated co...

Accumulative roll bonding is an advanced manufacturing process, which is capable of simultaneously refining the grain size into the nanometer regime and bonding different metallic sheet materials. Herein, homogenous aluminum/aluminum as well as heterogeneous aluminum/steel laminated metal composite (LMCs) are fabricated. The residual stresses are e...

Ultrafine-grained (UFG) metals produced by techniques of severe plastic deformation, such as equal channel angular pressing (ECAP), exhibit extraordinary strength properties. However, in the as-ECAP-processed state, the heavily deformed microstructure of such UFG metals is rather unstable and is prone to undergo grain coarsening (recrystallization)...

Copper sheets with graded and fine-grained (FG) microstructures were processed by accumulative roll bonding (ARB) and subsequent annealing to evaluate the effect of structural heterogeneities on the strength-ductility relationship. By an appropriate design of the individual ARB-process-steps, two types of graded structures (GSs) have been achieved...

Fatigue of metallic components is an important aspect in mechanical engineering. For example, the repeated pressure differences result in the fatigue of the fuselage of aircrafts. These high demands require the application of endurable and lightweight materials. In this context, laminated metal composites produced by the accumulative roll bonding p...

Due to their low density, magnesium alloys are very appealing for light-weight constructions. However, the use of the most common magnesium alloy, AZ91 (Mg 9 wt.% Al, 1 wt.% Zn), is limited to temperatures below 150 °C due to creep failure. Several alloys with an improved creep resistance have been developed in the past, for example the alloy MRI 2...

Choosing a properly optimized rotating scan strategy during the selective laser melting (SLM) process is essential to reduce residual stresses and thus to obtain homogeneous properties. Surprisingly, anisotropic material properties are found in several materials that are built with the often applied rotating stripes scan strategy of Electro‐Optical...

Additively manufactured austenitic stainless steel AISI 316L (EN 1.4404, X2CrNiMo17‐12‐2) is used at higher temperatures, e.g., in space applications. However, the high‐temperature properties of such materials have not been analyzed in detail yet. Thus, selective laser melted (SLM) 316L is tested in the solution‐annealed condition by compression an...

The influence of gradients in hardness and elastic properties at interfaces of dissimilar materials in laminated metallic composites (LMCs) on fatigue crack propagation is investigated experimentally for three different LMC systems: Al/Al-LMCs with dissimilar yield stress and Al/Steel-LMCs as well as Al/Ti/Steel-LMCs with dissimilar yield stress an...

The service life of technical components is often limited by the fatigue strength of the deployed materials. The accumulative roll bonding (ARB) process, which has the ability to produce ultrafine‐grained (UFG) laminated metal composites with tailored properties, offers a unique method to significantly enhance the fatigue life of materials that are...

Die soldering of die castings is a serious problem in the aluminum casting industry. The precise mechanism, the influence of the alloy composition, and the options for prevention have not yet been fully elaborated. A well-established solution for alloys with low iron content is the addition of manganese. However, up to 0.8 wt.% is necessary, which...

Determination of the true projected contact area by in situ indentation testing — ERRATUM - Gaylord Guillonneau, Jeffrey M. Wheeler, Juri Wehrs, Laetitia Philippe, Paul Baral, Heinz Werner Höppel, Mathias Göken, Johann Michler

A major limitation in nanoindentation analysis techniques is the inability to accurately quantify pile-up/sink-in around indentations. In this work, the contact area during indentation is determined simultaneously using both contact mechanical models and direct in situ observation in the scanning electron microscope. The pile-up around indentations...

In this study, we demonstrate how Zn and Sn influence hardening behavior and cluster formation during pre-aging and paint bake treatment in Al–Mg–Si alloys via hardness tests, tensile tests, and atom probe tomography. Compared to the standard alloy, the Sn-modified variant shows reduced cluster size and yield strength in the pre-aged condition. Dur...

There has been a long-standing controversy on how dislocations interact with interfaces. Here we report in-situ observations that in a Cu–brass heterostructured TEM film Frank–Read sources are the primary dislocation sources. They were dynamically formed and deactivated throughout the deformation in grain interior, which has never been reported bef...

Accumulative roll bonding (ARB) is a very useful method to produce ultrafine‐grained (UFG) sheet material with extraordinary mechanical properties. Besides the production of UFG mono‐materials, it is possible to create tailored multicomponent materials by stacking different materials. In this work, the aluminum alloy AA2024 and titanium grade1 are...

The focus of this paper is the designing of ultrafine‐grained aluminum/steel laminated metal composites for innovative lightweight materials concepts used for cyclic loading. These ultrafine‐grained composites are produced by the accumulative roll bonding process. Three different aluminum/steel composites are studied, where the position of the stee...

Hybrid materials present a convenient way of combining properties of more than one material in one product. However, there are problems associated with such manufacturing, particularly, in relation to the properties of the interface between components. Intermetallic compounds can potentially form in this area, whose size and composition can have a...

Aluminum laminates of high and technical purity layers were produced by accumulative roll bonding (ARB) at room temperature. To study the thermal stability, the laminates after 2 to 9 ARB cycles were annealed between 100 and 400 °C for one hour. Changes of the microstructure were analyzed by electron backscatter diffraction. For low ARB cycle numbe...

Polycrystalline copper (99.9%) was fatigued at a total strain amplitude of 0.1 and 0.2%, respectively. The tests were performed in situ under vacuum in a Large Chamber-Scanning Electron Microscope. By a repeated combination of in situ fatigue testing and ex situ focused ion beam milling, a deep insight into the mechanism of fatigue crack initiation...

This paper presents the high temperature yield and fatigue strength as well as thermophysical properties of two polycrystalline wrought γ/γ′ Co-base superalloys developed for application in a temperature regime above 700 °C. The alloys CoWAlloy1 (Co42Ni32Cr12Al6W3Ti2.5Ta1.5 + Si,C,B,Zr,Hf) and CoWAlloy2 (Co41Ni32Cr12Al9W5 + Ti,Ta,Si,C,B,Zr,Hf) exhi...

The influence of the layer architecture on the fatigue properties of ultrafine-grained laminated metal composites is studied. Composites with different stacking sequences of the aluminum alloys AA1050, AA5005, and AA2024 were produced by accumulative roll bonding and characterized by microstructural analysis and nanoindentation experiments. The fat...

The influence of interfaces on the fatigue life in AA1050/AA5005 ultrafine-grained laminated metal composites was investigated. At constant sheet thickness, the layer thickness and the number of material interfaces was varied by performing different cycles of accumulative roll bonding. It is found that crack deviation occurs if the crack approaches...

In this work laminated metal composites with alternating layers of commercial pure aluminum AA1050A and aluminum alloy AA5005 were produced by ARB. In order to vary the layer thickness and the number of interfaces different numbers of ARB cycles (4, 8 and 12) were applied. Subsequently, fatigue tests were performed and the related deformation and d...

Interfaces play a crucial role in mechanical behaviors of both laminated and gradient structured materials. In this work, copper/bronze laminates with varying interface spacing were fabricated by accumulative roll bonding and subsequent annealing to systematically study the interface effect on mechanical properties. Heterogeneities exist in chemica...

Ultrafine-grained accumulative roll bonded (ARB) sheet metals of aluminum alloys have a high potential for lightweight construction. The mechanical properties can be enhanced regarding strength and ductility by the combination of ARB and a local heat treatment according to the Tailor Heat Treated Blanks technology. The present investigation focuses...

It is well known that fatigue life of metallic materials involves processes at different stages. Two main regimes can be distinguished: The first is governed by plastic deformation and related dislocation processes like cyclic saturation and strain localization. The second regime is mainly dominated by crack initiation and propagation. Whether an i...

Laminated metal composites (LMCs) with alternating layers of commercial pure aluminum AA1050A and aluminum alloy AA5005 were produced by accumulative roll-bonding (ARB). In order to vary the layer thickness and the number of layer interfaces, different numbers of ARB cycles (4, 8, 10, 12, 14 and 16) were performed. The microstructure and mechanical...

Abstract Laminated metallic composites of 5 mm thickness, with a bimodal grain size distribution and alternating layers of commercial purity aluminum (Al99.5) and high purity aluminum (Al99.999) were successfully processed by accumulative roll bonding at room temperature up to 8 cycles. With increasing number of ARB cycles the layers of commercial...

Ultrafine-grained (UFG) metallic materials are at the cutting edge of modern materials science as they exhibit outstanding properties which make them very interesting for prospective structural or functional engineering applications. [...]

Ultrafine-grained AA7020 (AlZnMg) and AA7075 (AlZnMgCu) were produced by accumulative roll bonding (ARB) with up to 6 cycles. Different pre-heating treatments and their effect on the mechanical performance of the materials were investigated by means of hardness measurements and uniaxial tensile testing. It was found for AA7020 that by pre-heating a...

Austenitic stainless steels X4CrNi18-12 and X8CrMnNi19-6-3 were processed by accumulative roll bonding (ARB). Both materials show an extremely high yield strength of 1.25 GPa accompanied by a satisfactory elongation to failure of up to 14% and a positive strain rate sensitivity after two ARB cycles. The strain-hardening rate of the austenitic steel...

The accumulative roll bonding process is one of the most prominent severe plastic deformation processes for obtaining sheet materials with ultra-fine-grained microstructures and high strength. The properties of such sheets differ significantly from those of conventionally rolled sheets. It is hence desirable to have a simulation framework that can...

The low density of magnesium alloys makes them attractive for light weight constructions. However, important aspects are the rather poor mechanical properties of the most commonly used Mg alloy AZ91 (approximately 9 wt.-% Al, 1 wt.-% Zn), which limits its use in, e.g., power train applications. Alloying AZ91 with Ca leads to a significant improveme...

Over the last decades research activities in the field of very high cycle fatigue (VHCF) have strongly increased. It has been shown important to distinguish between single phase inclusion free type I and multiphase type II materials. Although, considerable efforts were made, the basic understanding of the dominating deformation/damage mechanisms is...

Sheets of aluminum AA6014 (AlMgSi) were successfully accumulative roll bonded from T4 condition up to eight cycles. Using the conventional ARB route, processing was on the one hand performed at room temperature. On the other hand, sheets were pre-heated in a furnace for 2.5 min at 210 °C prior to each rolling step. Besides the conventional ARB rout...

Die casting alloy based on aluminum-silicon, comprises secondary aluminum, 6-12 wt.% silicon, at least 0.3 wt.% iron, at least 0.25 wt.% manganese, at least 0.1 wt.% copper, 0.24-0.8 wt.% magnesium and 0.40-1.5 wt.% zinc, where the total content of iron and manganese on the die casting alloy is maximum of 1.5 wt.%, and the weight ratio of iron and...

After studying CO2 emissions caused by vehicles itself, automotive manufacturers now also consider CO2 emission during the production of vehicles and attempt to reduce them according to a holistic approach. This is where AUDI AG as first OEM together with AMAG Casting applies this approach at the production of structural components, which have been...

An accumulative swaging and bundling technique is used to prepare composite wires made of Ti and an Al alloy. These wires show reasonable higher yield stresses than expected from the pure material how curves. The additional strengthening in the composite is analyzed using nanoindentation measurements, tensile testings and investigations of the micr...

In this work stage I crack initiation in polycrystalline nickel-based superalloys is investigated by analyzing anisotropic mechanical properties, local stress concentrations and plastic deformation on the microstructural length scale. The grain structure in the gauge section of fatigue specimens was characterized by EBSD. Based on the measured data...

Accumulative roll bonding (ARB), as a method for production of ultrafine grained materials, is frequently supposed to be easily transferable to established industrial production lines. In literature, however, common sheet dimensions used for ARB in a laboratory scale are between 20 and 100 mm in width. In order to quantify the potential of upscalin...

The grain structure of coarse-grained Cu of different degrees of purity was modified by plastic deformation by , 4 and 8 passes of equal channel angular pressing (ECAP) at an ambient temperature with and without back pressure. The effect of this modification on deformation resistance was tested in rate change tests in compression at elevated temper...

Aluminium–titanium (Al/Ti) composite sheets were fabricated via asymmetric accumulative roll bonding (AARB), which capitalises on additional shear to enhance plastic deformation. Multi-layers of Al alloy (AA1050) and commercially-pure Ti sheets were alternatively stacked and rolled-bonded with varied roll diameter ratios (dr) ranging from 1 to 2, f...

Laminates of high and commercial purity aluminium layers were processed by accumulative roll bonding performed up to ten cycles. The mechanical properties were measured by tensile testing. Both yield strength and ultimate tensile strength increase with higher number of cycles. The fracture strain is decreased through the first ARB cycle, but increa...

During the last decades the interest in fatigue properties of materials subjected to more than 10(7) cycles has strongly increased. To reach such high numbers of cycles the use of ultrasonic fatigue testing systems is a well-established method due to their very high fatigue frequencies. However particular considerations about the specimen design ha...

In the current study the mechanical properties of ultra-fine grained low carbon steel processed by conventional equal channel angular pressing and a continuous equal channel angular pressing-Conform process were investigated. Both monotonic and cyclic properties were determined for the steel in either condition and found to be very similar. Microst...

The surface strain evolution in accumulative roll bonded aluminum alloys was studied in situ using digital image correlation. Laminated multicomponent materials, consisting of two ultrafine-grained aluminum alloys with different layer architectures (laminate and sandwich), were analyzed and compared to the pure alloys after the same number of accum...

Graded distributions of copper particles in ultrafine-grained aluminium sheets are produced by accumulative roll bonding and particle reinforcement. The metallic copper particles are sprayed on the sheet surfaces under variation of spray distance and/or relative velocity of the spray gun to the sheet. Therewith, the particle content could be varied...

Ultrafine-grained (UFG) materials are widely known to exhibit significantly improved fatigue properties when the fatigue life is regarded in a Wöhler-S–N-plot. More detailed, the achieved improvements in fatigue life significantly depend on the processing conditions of these UFG materials. In this work the influence of several equal channel angular...

Cover: Sensitization in stainless steels is associated with precipitation of chromium rich carbides along grain boundaries during the detrimental heat treatments. This phenomenon was also found in automotive exhaust applications. Some commonly used grades were investigated during a research project. The precipitation of chromium carbides were obser...

Aluminum alloy AA6016 was accumulative roll bonded up to eight cycles and investigated regarding formability by bending tests. Due to the limited bendability of accumulative roll bonding (ARB) processed materials, a tailored laser heat treatment was performed along the bending edge before forming. This tailored laser heat treatment causes a local r...

Aluminium laminates consisting of high-purity aluminium and commercially pure aluminium have been produced by accumulative roll bonding (ARB) at ambient temperature for up to 10 cycles. To study the microstructure and texture development of the high-purity aluminium layers with regard to the shrinking layer thickness during ARB, microstructure and...

A diecasting alloy based on Al-Si is made of 6 to 12% by weight of silicon (Si), at least 0.3% by weight of iron (Fe), at least 0.25% by weight of manganese (Mn), at least 0.1% by weight of copper (Cu), 0.24 to 0.8% by weight of magnesium (Mg) and 0.40 to 1.5% by weight of zinc (Zn). The alloy also has 50 to 300 ppm of strontium (Sr) and/or 20 to 2...

The influence of a hydrogenated amorphous carbon coating on the fatigue life of an austenitic steel was evaluated in this work. The fatigue damage mechanisms have been compared for both coated and uncoated specimens. A strong increase in fatigue life of more than 300% for total strain amplitudes smaller than 4×10−3 was found for the coated specimen...

Laminates with alternating AA6014 and AA5754 layers are produced by accumulative roll bonding (ARB). Depending on the number of ARB cycles the microstructure and the mechanical properties are investigated. The microstructure is characterized by scanning electron microscopy and correlated to the local mechanical properties determined by nanoindentat...

Aluminium alloy AA6016 was accumulative roll bonded up to eight cycles in order to produce an ultrafine-grained microstructure. The formability of these sheets was investigated by means of bending tests. Furthermore the influence of a local laser heat treatment at the bending edge is observed. The strength of the UFG samples is increased by a facto...

The monotonic and cyclic deformation behavior of ultrafine-grained metastable austenitic steel AISI 304L, produced by severe plastic deformation, was investigated. Under monotonic loading, the martensitic phase transformation in the ultrafine-grained state is strongly favored. Under cyclic loading, the martensitic transformation behavior is similar...

This chapter provides an overview of the development and application of nanostructured coatings, with an emphasis on the latest results on metal-base materials. Thermal spray processing of nanostructured ceramic coatings have been successfully implemented in Navy and industrial applications. Thermal and cold spray processes have been used to deposi...

The plastic anisotropy was studied on aluminium sheets with layers of different purity (A: 5N and B: 2N+) produced by accumulative roll bonding (ARB). Both material layers show a contrasting recrystallization behavior where A and B are discontinuously and continuously recrystallized, respectively. Global textures were measured by neutron diffractio...

The formation of alloys by particle reinforcement during accumulative roll bonding (ARB), and subsequent annealing, is introduced on the basis of the binary alloy system Al-Cu, where strength and electrical conductivity are examined in different microstructural states. An ultimate tensile strength (UTS) of 430 MPa for Al with 1.4 vol.% Cu was reach...

In order to achieve a reasonable lifetime of automotive exhaust components, a large number of high alloyed ferritic and austenitic stainless steels are used nowadays. It is a common concept that the lifetime of a component is directly related to the performance of steel against corrosion. The components are divided into different sections depending...

Accumulative roll bonding (ARB) is a very attractive process for processing large sheets to achieve ultrafine-grained microstructure and high strength. Commercial purity Al and many Al alloys from the 5xxx and the precipitation strengthened 6xxx alloy series have been successfully processed by the ARB process into an ultrafine-grained state and sup...

A nanoindentation strain-rate jump technique has been developed for determining the local strain-rate sensitivity (SRS) of nanocrystalline and ultrafine-grained (UFG) materials. The results of the new method are compared to conventional constant strain-rate nanoindentation experiments, macroscopic compression tests, and finite element modeling (FEM...

Several processes of severe plastic deformation are suitable for the production of materials with ultrafine-grained microstructures which are known to exhibit high strength and often good ductility as well as strain rate sensitive behavior. The most promising ones are equal channel angular pressing (ECAP) for bulk material and accumulative roll bon...

Ultrafine-grained (UFG) metals produced by equal channel angular pressing (ECAP) exhibit outstanding mechanical properties. They show high strength under monotonic loading as well as strongly enhanced fatigue lives in the Wöhler S–N-plot compared to their coarse grained (CG) counterparts. It could be shown that the fatigue lives can be significantl...

Nanocrystalline materials are very promising for modern lightweight engineering applications due to their extraordinary mechanical properties under monotonic as well as under cyclic loading. In particular, the fatigue properties of nanostructured metals and alloys are one of the key issues for the successful use of this new class of materials in en...

Ceramic nanoparticles produced by comminution are introduced homogeneously during accumulative roll bonding (ARB) in aluminium AA1050A by airgun spraying from a stabilized aqueous suspension. In the so-produced nanoparticle-reinforced ultrafine-grained material, acceleration of microstructural evolution during the early ARB cycles as well as reduce...

Investigations of the fatigue behaviour of commercial pure (CP) aluminium and the aluminium alloy AA6082 have been carried out in the very high cycle fatigue (VHCF) regime up to 1 × 1010 cycles. The evolution of surface roughening was investigated with light, scanning electron and atomic force microscopy, from which the relevant deformation and dam...

The effect of the cobalt content and WC grain size on the deformation behaviour of WC-Co hard metals was investigated by studying materials with a varying WC grain size and cobalt content. The WC grain size ranged from 2.65 to 0.25 µm and the binder content ranged from 6 to 15 wt%. Single and multiple scratch tests were conducted using a Nano inden...

In ultrafine-grained (UFG) materials produced by severe plastic deformation (SPD) techniques such as ECAP (equal channel angular pressing), bimodal grain size distributions have been observed under different circumstances, for example shortly after ECAP, after rest or anneal and/or after mild cyclic deformation at rather low homologous temperature....

Dispersed nanoparticles are introduced from stabilized suspensions during the accumulative roll bonding process in aluminium AA1050A by air gun spraying up to a final volume fraction of 0.1 % after eight cycles. Additional strengthening caused by particle insertion is observed and strongly depends on the suspension medium and stabilizing agent as b...

Among the well-known methods of severe plastic deformation the accumulative roll bonding (ARB) process is most promising for producing ultrafine-grained (UFG) materials with extraordinary mechanical properties at an industrial scale. Besides, it has also been shown that the ARB process can be successfully used to produce multi-component materials w...

Texture, microstructure, and tensile behavior of technically pure aluminum AA1050 and of the age-hardening alloy AA6016 produced by accumulative roll bonding (ARB) were studied for different numbers of ARB cycles. After eight cycles an ultrafine grained microstructure with grain sizes of the order of 0.5 µm is reached. The grain size decreases with...

Bulk ultrafine-grained (UFG) metals and alloys prepared by techniques of severe plastic deformation (SPD), in particular by equal channel angular pressing (ECAP), exhibit exceptional mechanical properties. With respect to potential applications of this new class of very fine-grained bulk materials, the cyclic deformation and fatigue behaviour, rela...

Accumulative roll bonding (ARB) as a method of severe plastic deformation is a well-established process to produce ultrafine-grained (UFG) sheet materials with extraordinary mechanical properties. In this work ARB is applied to combine different sheet materials in order to tailor the materials properties by producing sandwich-like structures. The h...

The mechanical properties of bulk ultrafine-grained materials produced by severe plastic deformation can be modified (sometimes enhanced) by a mild annealing treatment which leads, in some cases, to a bimodal grain size distribution, characterized by a good combination of strength and ductility. Bimodal grain size distributions can also evolve duri...

In this study Ti-foils were roll bonded together with commercially pure aluminium AA1050. The laminates were produced by using two 1 mm thick AA1050 sheets at the outer side of the stack combined with 100 μm thick Ti-foils as an intermediate layer for each accumulative roll bonding process. The samples were rolled up to 4 ARB cycles. Subsequently t...

The aluminium alloy AA5754 is used for many technical applications. In this work, the accumulative roll bonding process is applied to this alloy in order to investigate the potential of an ultrafine-grained structure on the mechanical properties of this Al-Mg alloy. Sheets from AA5754 (AlMg3) were successfully processed by accumulative roll bonding...

Accumulative roll bonding (ARB) as a method of severe plastic deformation (SPD) is an interesting established process to produce ultrafine-grained (UFG) sheet materials with high potential for light weight constructions. The ARB process offers a high flexibility for tailored material design. Al2O3 particles, carbon fibers and titanium foils are use...

It is meanwhile established that the "classical" fatigue limit in the Wohler-SN-plot at approximately 10(7) cycles is not generally valid for the design of components subjected to loading in the VHCF-regime. Fatigue failure of metallic materials might occur even at stress amplitudes below the "classical" fatigue limit in the VHCF regime. However, t...

In order to quantify the plastic anisotropy of the ultrafine grained aluminium alloy AA6016 produced by accumulative roll-bonding (ARB) the Lankford parameter is measured by tensile testing as a function of the number of ARB cycles. The experimental results are compared with those from texture-based Taylor simulations. Increasing differences betwee...

The present study investigates passivity and localized corrosion of ultrafine-grained (UFG) binary Al-alloys with 0.5, 1 and 2 wt.% of magnesium subjected to three different equal-channel angular pressing (ECAP) pass numbers. The alloys were investigated by electrochemical techniques and surface analyses in different NaCl solutions and compared wit...

Among various SPD processes used for producing nanocrystalline and ultra-fine grain (UFG) materials, Equal Channel Angular Pressing (ECAP), is the most well developed processing technique. In the present work, the technologically interesting aluminium alloy AA6061 was selected for study. The strain rate sensitivity of AA6061 has been investigated i...

During their operational life-time, actively cooled liners of cryogenic combustion chambers are known to exhibit a characteristic so-called doghouse deformation, pursued by formation of axial cracks. The present work aims at developing a model that quantitatively accounts for this failure mechanism. High-temperature material behaviour is characteri...

Introduction and Motivation and MotivationFatigue Life of UFG MaterialsCyclic Deformation Behavior and Damage MechanismsModelingCriteria for Optimizing the Cyclic Deformation BehaviorReferences

Ultrafine-grained sheets of the commercial-purity aluminium AA1050 and the aluminium alloy AA6016 were processed by accumulative roll bonding. As-received, conventionally grained and ultrafine-grained aluminium sheets with an average grain size ranging from 20μm to 30μm and 200nm, respectively, were successfully joined by friction stir welding, and...

In this study the cyclic deformation behavior and fatigue lives of Ti–6Al–4V ELI (extra low interstitials) alloy with conventional grain sized and ultrafine-grained (UFG) microstructure are investigated. The UFG condition was obtained by a combination of equal channel angular pressing followed by thermomechanical treatment. Fatigue experiments were...

It was shown that introducing an ultrafine-grained (UFG) microstructure in pure metals as well as some alloys leads to strongly enhanced fatigue properties. The cyclic deformation behavior of UFG Ti-6Al-4V ELI (extra low interstitials) alloy is studied by both strain and stress controlled fatigue tests using plastic strain amplitudes between 3×10−4...