Mustafa Awd

TU Dortmund University

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Frank Walther

TU Dortmund University

Shafaqat Siddique

University of Lahore

Jochen Tenkamp

TU Dortmund University

Abdul Khadar Syed

Coventry University

Claus Emmelmann

Hamburg University of Technology

Lobna Saeed

University of Bremen

Jan Johannsen

Fraunhofer Research Institution for Additive Manufacturing Technologies IAPT

Xiang Zhang

Southwest Jiaotong University

Mohamed Merghany

TU Dortmund University

Ali Fatemi

University of Memphis

Cooperative Institutions

TU Dortmund University

Cranfield University

Coventry University

Saarland University

Ruhr University Bochum

Pontifical Catholic University of Rio de Janeiro

Catholic University of America

Brandenburg University of Technology Cottbus-Senftenberg

Walter de Gruyter (Germany)

The Open University

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Mechanical and Microstructural Characterization of Arc-Welded Inconel 625 Alloy

Materials (2019)

Daniel Kotzem Lucas Beermann Mustafa Awd Frank Walther

The objective of this work was to verify a relatively new fusion-based additive manufacturing (AM) process to produce a high-temperature aerospace material. The nickel-based superalloy Inconel 625 (IN625) was manufactured by an arc-based AM technique. Regarding microstructure, typical columnar-oriented dendritic structure along the building direction was present, and epitaxial growth was visible. The mechanical behavior was characterized by a combination of quasi-static tensile and compression tests, whereas IN625 showed high yield and ultimate tensile strength with a maximum fracture strain of almost 68%. Even quasi-static compression tests at room and elevated temperatures (650 °C) showed that compression strength only slightly decreased with increasing temperature, demonstrating the good high-temperature properties of IN625 and opening new possibilities for the implementation of arc-based IN625 in future industrial applications.

Inconel 625

Inconel

10.3390/ma12223690

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Citations (7)

Criticality of porosity defects on the fatigue performance of wire + arc additive manufactured titanium alloy

International Journal of Fatigue (2019)

Romali Biswal Xiang Zhang Abdul Khadar Syed Mustafa Awd Jialuo Ding

Titanium alloy

10.1016/j.ijfatigue.2019.01.017

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Citations (167)

Microstructure and Fatigue Damage Evolution in Additive-Manufactured Metals Using Enhanced Measurement Techniques and Modeling Approaches

The minerals, metals & materials series (2021)

Mustafa Awd Frank Walther Shafaqat Siddique Ali Fatemi

Characterization

Fatigue limit

10.1007/978-3-030-65261-6_68

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Citations (1)

Very high-cycle fatigue properties and microstructural damage mechanisms of selective laser melted AlSi10Mg alloy

International Journal of Fatigue (2019)

Mustafa Awd Shafaqat Siddique Jan Johannsen Claus Emmelmann Frank Walther

Quasistatic process

Coalescence (physics)

Quasistatic loading

Fatigue limit

10.1016/j.ijfatigue.2019.02.040

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Citations (56)

Effect of microstructural heterogeneity on fatigue strength predicted by reinforcement machine learning

Fatigue & Fracture of Engineering Materials & Structures (2022)

Mustafa Awd Sebastian Münstermann Frank Walther

Abstract The posterior statistical distributions of fatigue strength are determined using Bayesian inferential statistics and the Metropolis Monte Carlo method. This study explores how structural heterogeneity affects ultrahigh cycle fatigue strength in additive manufacturing. Monte Carlo methods and procedures may assist estimate fatigue strength posteriors and scatter. The acceptable probability in Metropolis Monte Carlo relies on the Markov chain's random microstructure state. In addition to commonly studied variables, the proportion of chemical composition was demonstrated to substantially impact fatigue strength if fatigue lifetime in crack propagation did not prevail due to high threshold internal notches. The study utilizes an algorithm typically used for quantum mechanics to solve the complicated multifactorial fatigue problem. The inputs and outputs are modified by fitting the microstructural heterogeneities into the Metropolis Monte Carlo algorithm. The main advantage here is applying a general‐purpose nonphenomenological model that can be applied to multiple influencing factors without high numerical penalty.

Fatigue limit

10.1111/ffe.13816

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Citations (11)

A Review of Different Methods for Joining of Bi-Metallic Materials by Friction Welding

International Journal of Engineering Research and (2014)

Mohamed Harraz Mustafa Awd Adham Al-Sayyad

The hybrid joining between different bi-metallic materials has become extremely important in many industrial applications especially where the combination of strength and weight reduction is needed. High temperature materials such as high strength steels and Ti alloys combined with lightweight materials such as aluminium are widely being used in many industrial applications and particularly in the automotive and aerospace industries. Traditional fusion welding processes introduce significant amount of heat into the material and frequently lead to property deterioration, such as cracking and porosity during solidification. On the other hand the hybrid joining between different bi-metallic materials using conventional welding techniques are not possible. These problems could be overcome by the use of the recently developed solid state friction welding approaches. This review paper focuses on aspects of rotary friction welding of high performance and high-temperature materials combined with lightweight alloys, and introduce a new realization for friction welding of incompatible bimetals.

Fusion welding

Friction Welding

Explosion welding

Plastic welding

Source

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Citations (2)

Towards Deterministic Computation of Internal Stresses in Additively Manufactured Materials under Fatigue Loading: Part I

Materials (2020)

Mustafa Awd Mhd Fateh Labanie Kerstin Moehring Ali Fatemi Frank Walther

The ongoing studies of the influence of internal defects on fatigue strength of additively manufactured metals adopted an internal crack or notch-like model at which the threshold stress intensity factor is the driving mechanism of fatigue failure. The current article highlights a shortcoming of this approach and offers an alternative based on X-ray microcomputed tomography and cyclic plasticity with a hybrid formulation of Chaboche and Armstrong-Frederick material laws. The presented tessellation and geometrical transformation scheme enabled a significantly more realistic morphological representation of internal defects that yielded a cyclic strain within 2% of the experimental values. This means that cyclic plasticity models have an accurate prediction of mechanical properties without repeating a full set of experiments for additively manufactured arbitrary microstructures. The coupling with a material law that is oriented towards the treatment of cyclic hardening and softening enabled more accurate computation of internal stresses under cyclic loading than ever before owing to the maturity of tessellation and numerical tools since then. The resulting stress-strain distributions were used as input to the Fatemi-Socie damage model, based on which a successful calculation of fatigue lifetime became possible. Furthermore, acting stresses on the internal pores were shown to be more than 450% concerning the applied remote stress amplitude. The results are a pretext to a scale bridging numerical solution that accounts for the short crack formation stage based on microstructural damage.

Hardening (computing)

Internal stress

10.3390/ma13102318

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Citations (11)

Interrupted fatigue testing with periodic tomography to monitor porosity defects in wire + arc additive manufactured Ti-6Al-4V

Additive manufacturing (2019)

Romali Biswal Xiang Zhang Muhammad Shamir Abdullah Al Mamun Mustafa Awd

Porosity defects remain a challenge to the structural integrity of additive manufactured materials, particularly for parts under fatigue loading applications. Although the wire + arc additive manufactured Ti-6Al-4 V builds are typically fully dense, occurrences of isolated pores may not be completely avoided due to feedstock contamination. This study used contaminated wires to build the gauge section of fatigue specimens to purposely introduce spherical gas pores in the size range of 120–250 micrometres. Changes in the defect morphology were monitored via interrupted fatigue testing with periodic X-ray computed tomography (CT) scanning. Prior to specimen failure, the near surface pores grew by approximately a factor of 2 and tortuous fatigue cracks were initiated and propagated towards the nearest free surface. Elastic-plastic finite element analysis showed cyclic plastic deformation at the pore root as a result of stress concentration; consequently for an applied tension-tension cyclic stress (stress ratio 0.1), the local stress at the pore root became a tension-compression nature (local stress ratio −1.0). Fatigue life was predicted using the notch fatigue approach and validated with experimental test results.

Cyclic stress

Tension (geology)

Strain gauge

10.1016/j.addma.2019.04.026

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Citations (76)

Comparison of Various Intrinsic Defect Criteria to Plot Kitagawa–Takahashi Diagrams in Additively Manufactured AlSi10Mg

Materials (2023)

Mohammed Intishar Nur Meetkumar Soni Mustafa Awd Frank Walther

Selective laser melting is a form of additive manufacturing in which a high-power density laser is used to melt and fuse metallic powders to form the final specimen. By performing fatigue and tensile tests under various loading conditions, the study sought to establish the impact of internal defects on the specimens' fatigue life. Scanning electron microscopy and finite element simulation were conducted to determine the defect characteristics and the stress intensity factor of the specimens. Four different methods were used to determine the intrinsic defect length of the specimen, using data such as grain size, yield strength, and hardness value, among others. Kitagawa-Takahashi and El-Haddad diagrams were developed using the results. A correction factor hypothesis was established based on the deviation of measured data. Using Paris law, fatigue life was determined and compared to the experimental results later. The study aims to select one or more approaches that resemble experimental values and comprehend how internal defects and loading situations affect fatigue life. This study's findings shed light on how internal defects affect the fatigue life of selective laser-melted AlSi10Mg specimens and can aid in improving the fatigue life prediction method of additively manufactured components, provided an appropriate intrinsic crack criterion is selected.

Fatigue limit

Selective Laser Melting

Intensity

10.3390/ma16186334

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Citations (1)

Fracture–Mechanical Assessment of the Effect of Defects on the Fatigue Lifetime and Limit in Cast and Additively Manufactured Aluminum–Silicon Alloys from HCF to VHCF Regime

Metals (2020)

Jochen Tenkamp Mustafa Awd Shafaqat Siddique Peter Starke Frank Walther

Aluminum–silicon alloys are commonly used in die-cast and additively manufactured (AM) light-weight components due to their good processability and high strength-to-weight ratio. As both processing routes lead to the formation of defects such as gas and shrinkage porosity, a defect-sensitive design of components is necessary for safe application. This study deals with the fatigue and crack propagation behavior of die-cast alloy AlSi7Mg0.3 and additively manufactured alloy AlSi12 and its relation to process-induced defects. The different porosities result in significant changes in the fatigue stress-lifetime (S–N) curves. Therefore, the local stress intensity factors of crack-initiating defects were determined in the high and very high cycle fatigue regime according to the fracture mechanics approach of Murakami. Through correlation with fatigue lifetime, the relationship of stress intensity factor (SIF) and fatigue lifetime (N) could be described by one power law (SIF–N curve) for all porosities. The relationship between fatigue limit and defect size was further investigated by Kitagawa–Takahashi (KT) diagrams. By using El Haddad’s intrinsic crack length, reliable differentiation between fracture and run out of the cast and AM aluminum alloys could be realized. SIF–N curves and KT diagrams enable a reliable fatigue design of cast and AM aluminum alloys for a finite and infinite lifetime.

Fatigue limit

Shrinkage

10.3390/met10070943

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Citations (27)