Forthcoming articles


International Journal of Microstructure and Materials Properties


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International Journal of Microstructure and Materials Properties (30 papers in press)


Regular Issues


  • The Influence of Laser Parameters on the Hardness Studies and Surface Analyses of Laser Alloyed Stellite-6 Coatings on AA 1200 Alloy: Response Surface Model Approach   Order a copy of this article
    Abstract: Improving the hardness values of AA1200 aluminium alloy using stellite-6 ceramic powder was investigated. A 4.4 kW Rofin Sinar Nd:YAG laser emitting 1.064
    Keywords: Hardness; Microstructure; AA1200; Stellite-6; and Factorial design.

  • Microstructural Features induced during Compression of Al-18Si-2.5Cu-0.6Fe Alloy at Elevated Temperature   Order a copy of this article
    by Khemraj Sahu, A.K. Jha, S.N. Ojha 
    Abstract: The research objective of the present paper is to study the feasibility of bulk processing of Al-18Si-2.5Cu-0.6Fe alloy. The microstructural features induced during high speed compression of alloy under different processing conditions have been investigated and reported. The compression of a cylindrical test specimens between top and bottom impression dies and also through a converging die at elevated temperatures has been considered for study. Experiments have been performed with different aspect and reduction ratios for impression and converging die compression respectively. The results reveal that considerable refinement in the microstructure of the compressed alloy occurred and is more significant in converging die compression at elevated temperature. The development of microstructural features during hot compression of the alloy at different processing conditions were also discussed. The results of the present study provide a valuable insight to understand the microstructural refinement during high speed compression at elevated temperatures.
    Keywords: Al-18Si-2.5Cu-0.6Fe alloy; impression die compression; converging die compression; working temperature; high speed compression; reduction ratio; aspect ratio; microstructural feature.

  • Forming limit prediction of sheet metals by M-K model with various yield functions   Order a copy of this article
    by Jie Zhu, Shangyu Huang, Wei Liu, Jianhua Hu, Xifan Zou 
    Abstract: In order to investigate the influence of yield function on the accuracy of predicting forming limit curve for sheet metal, Mises, Hill48 and Yld2000-2d yield functions were implemented in the M-K model. The parameter identification methodology of Hill48 and Yld2000-2d anisotropic yield functions was also investigated. For the AA5182-O aluminum alloy and TRIP780 steel sheets, the parameters of yield functions were identified respectively and the forming limit curves were numerically predicted with the identified yield functions. By comparison of the predicted uniaxial yield stresses, uniaxial anisotropic coefficients and forming limit curves with the experimental results, the Yld2000-2d yield function is found to be more accurate for modelling the anisotropy and formability of sheet metal than Mises and Hill48 yield functions, especially in the biaxial tension region of forming limit curve.
    Keywords: Forming limit; Anisotropic yield function; M-K model; Parameter identification.

  • Critical Aspects of Pulse Current GMA Welding of Stainless Steel Influencing Metallurgical Characteristics   Order a copy of this article
    by Shrirang G. Kulkarni, B.P. Agrawal, P.K. Ghosh, Subrata Ray 
    Abstract: Metallurgical characteristics of weld of austenitic stainless steel has been studied as a function of pulse parameters, heat input and heat transferred to the weld pool in pulsed current gas metal arc welding process. The combined influence of these three aspects on microstructure and hardness of weld bead and heat affected zone has been thoroughly investigated. Inter granular corrosion susceptibility of heat affected zone of different weld has also been investigated. The characteristics of pulse current gas metal arc weld have been compared with conventional gas metal arc welds at similar heat inputs. The pulse parameters are suggested which will produce superior quality relative to gas metal arc welding as research goal. The superiority of pulse current gas metal arc weld has been justified.
    Keywords: Pulse current gas metal arc welding; pulse parameters; microstructure; inter granular corrosion; Austenitic stainless steel.

  • Adsorption and Corrosion Inhibition Properties of Floxapen Compound on the Electrochemical Characteristics of Type-A5-series Aluminium in Sodium Chloride Solution   Order a copy of this article
    by Ojo Sunday Fayomi, O.A. Bamgboye, B.M. Durodola, W.A. Inam, A.A. Daniyan 
    Abstract: The inhibition performance of floxapen compounds on the electrochemical corrosion behaviour of A5 series aluminium in 3.5% NaCl acid solutions was studied through weight loss method and potentiodynamic polarization test. The results obtained showed that the organic drug compound performed effectively in sodium chloride solutions with average floxapen compounds inhibition efficiency of 68% from weight loss and potentiodynamic polarization test respectively. Results from corrosion thermodynamic calculations showed that the adsorption of floxapen compounds onto the aluminium was through chemisorption mechanism whereby the redox electrochemical progression responsible for corrosion initiation and the electrolytic transport of corrosive anions were concurrently suppressed. Adsorption of the compound was determined to obey the Langmuir and Frumkin isotherm model.
    Keywords: Adsorption; Floxapen; Aluminium alloy; Inhibition.

  • Deep cryogenic treatment and tempering of the X153CrMoV12 cold work steel   Order a copy of this article
    by Aleksander Ciski 
    Abstract: The aim of work was to analyse the way of proceeding of the processes accompanying deep cryogenic treatment of X153CrMoV12 cold work tool steel. Properties of X153CrMoV12 steel subjected to DCT and subsequent tempering at different temperatures are presented. The study includes microscope observations, measurements of hardness, wear resistance test and impact strength test. Precipitation processes occurring during tempering of the deep cryogenically treated steel led to shifting of the maximum hardness peak to the lower temperature as well as to the reduction of obtained maximum hardness. These effects are associated with a reduced content of retained austenite and altered precipitation processes. Precipitation process after DCT leads to a higher quantity of fine secondary carbides, due to changes made in the matrix and creating of additional nucleation sites by movement of the mobile dislocations. Carbides with dimensions smaller than 1
    Keywords: deep cryogenic treatment; tempering; cold work steel; X153CrMoV12; precipitation of carbides; secondary hardening; retained austenite; hardness; microstructure; wear;.

  • Modelling and simulation of nitriding process in SCM420 steel   Order a copy of this article
    by Xiaohu Deng, Dong-ying Ju 
    Abstract: In order to predict the nitrogen diffusion, phase transformation and hardness during nitriding process of the complicated steel workpiece. A coupled model that combines a multi-physical field theory with a finite element method has been developed to simulate the nitriding process. It is considered the interaction among diffusion, transformation and temperature in multi-physical field model. A phenomenological model is presented to simulate the micro structural evolution of the nitride layer. The distribution of nitrogen concentration is calculated using a customized finite element program called COSMAP. The model can predict nitrogen content, iron-nitrogen phase compositions and hardness. To validate the coupled model, the nitriding process of SCM420 cylinder and helical gear is simulated. It can be concluded that the present model can reflect the geometrical effect of the complex workpieces during the nitriding process. The simulated results are consistent reasonably with the available experimental results and the theoretical conclusions.
    Keywords: nitriding; low alloy steel; multi-field; finite element.

  • Effect of laser shock processing and heat treatment sequence on surface layer characteristics of high strength Ni-Co-Mo steel   Order a copy of this article
    by Luca Petan, José Luis Ocaña, Juan Antonio Porro, Janez Grum 
    Abstract: Tool steels operate in demanding environments since they are usually exposed to chemical, mechanical, and thermal detrimental phenomena. Therefore, there is an interest in investigating surface engineering techniques that can improve their surface characteristics. This paper presents the results our research, where the effects of laser shock peening on Ni Co Mo maraging steel were investigated by analysing the surface integrity. Maraging steels do not achieve their maximum strength after quenching, but after precipitation hardening. Consequently, there is a distinct difference in the mechanical properties between the solution annealed condition and precipitation hardened condition. Because of their particular heat treatment process, the effects of laser shock peening were analysed before and after different sequences of laser peening and heat treatment stages to determine whether the choice of order significantly influences the surface integrity.
    Keywords: Die casting; thermal fatigue; cracking; laser shock peening; residual stress; maraging steel.

  • Effect of quasi-static pre-strain on electromagnetic forming limits for high strength steel sheets   Order a copy of this article
    by Yu Lei, Shangyu Huang, Wei Liu, Shiwei Yan, Mengcheng Zhou, Jianhua Hu, Xifan Zou 
    Abstract: The forming limits of high strength steel sheets DP590 and B280VK were experimentally investigated at three kinds of strain rates, including: quasi-static loading, electromagnetic loading and hybrid loading. For the quasi-static and electromagnetic hybrid loading, the high strength steel sheets with different pre-strain levels at quasi-static loading condition were sequentially deformed by electromagnetic loading. It can be observed that the hybrid electromagnetic forming limits of both high strength steel sheets DP590 and B280VK are much higher than those at quasi-static or electromagnetic loading conditions. Meanwhile, the experiment results show that the hybrid electromagnetic forming limits are affected by the level of quasi-static pre-strain, and the hybrid electromagnetic forming limits with the quasi-static pre-strain of 2.5% and 7% are higher than those with the largest quasi-static pre-strain of 16%.
    Keywords: prestrain; hybrid electromagnetic forming; forming limit; high strength steel.

  • Assessment of porosity of glass-ionomer cement using ultrasonic waves   Order a copy of this article
    by Bassidi Touriya, Lahcen Mountassir, Hassan Nounah, Khalid Bouabid 
    Abstract: The degradation of dental restoration with glass ionomer cement is generally caused by the penetration of aggressive agents through the pores. Therefore the porosity is an essential parameter in the degradation process and an indicator of durability of this restoration. The objective of this study was to investigate the relationship between porosity and ultrasonic parameters of glass-ionomer dental cement. Theoretical Schoch model describing the ultrasonic propagation in materials was proposed. Ultrasonic velocities and mechanical properties were evaluated. They were then, compared to the experimental ultrasonic parameters measured on dry and saturated samples with varying porosity. As expected, a linear decrease of ultrasonic velocities versus porosity is observed for two saturation states. The correlation between theoretical and measured results is analyzed. The Schoch model succeeded in describing the acoustic parameters in dry and saturated state.
    Keywords: Glass-ionomer cement; Ultrasound; porosity; Mechanical properties.

Special Issue on: Induction Heating and Heat Treatment

  • Technologies advancing scan & single-shot induction hardening capabilities   Order a copy of this article
    by Collin Russell 
    Abstract: This paper presents recent inverter and inductor innovations that have advanced the performance and capability of modern scan and single-shot induction hardening equipment. The physics and critical design elements of both of these induction heat treatment processes are discussed in detail and practical case studies featuring numerical computer simulation are referenced throughout.
    Keywords: Induction heat treatment; scan hardening; single-shot hardening; computer simulation.

  • ELTA 7.0 program for induction heat treatment of gears   Order a copy of this article
    by Vladimir Bukanin, Alexander Ivanov, Alexei Zenkov 
    Abstract: Induction heat treatment of gear is a very complicated technology and needs to be investigated in detail. A great deal of researches using experimental methods and 3D computer simulation has been carried out to obtain required mechanical properties of steel. In order to perform these tasks more efficiently the authors offered to use a new version of ELTA with a special Gear Application. An idea of 2D gear model, methods and structure of program is described. ELTA 7.0 can calculate integral parameters of inductor and temperature in the cross-section of gear for heating and cooling stages simpler and faster than in the case of 3D simulation. Several examples of induction hardening with single and double variable frequencies of power source are presented.
    Keywords: gear hardening; induction heating; cooling diagram; ELTA 7.0 program.

  • Modelling and optimisation of electromagnetically coupled solid manufacturing processes   Order a copy of this article
    by Francois Bay, Jose Alves, Julien Barlier 
    Abstract: Electromagnetically-coupled manufacturing processes cover a wide range of applications such as magnetic pulse forming processes or induction heat treatment processes. This paper presents a computational model and numerical tool developed in our laboratory for modelling these processes taking into account their specificities.
    Keywords: Electromagnetic coupled processes; Multiphysics couplings; Finite elements; Optimisation.

  • Computer Simulation of Single Frequency Induction Surface Hardening of Gear Wheels Analysis of Selected Problems   Order a copy of this article
    by Jerzy Barglik, Adrian Smagór, Albert Smalcerz 
    Abstract: Abstract: Induction surface hardening of gear wheels is a complex technological process making possible to obtain a thin hardened surface zone of the tooth and to keep soft their internal part. Mathematical modeling of the process is still a serious challenge. It requires triply coupled simulation of non-linear, transient physical fields mostly in 3D formulation. The paper deals with the analysis of various factors influencing on accuracy of computations including material properties, heat transfer parameters and modified values of critical temperatures. The main goal of the paper is to evaluate an influence of three material properties on the accordance between computations and measurements. Exemplary investigations are provided for the single frequency induction hardening of gear wheels made of steel 41Cr4.
    Keywords: induction surface hardening; material properties; coupled problems; austenitization; modified upper critical temperature,.

  • Optimal design of inductor addressed to a tailored heating forging process   Order a copy of this article
    by Marco Baldan, Thomas Steinberg, Egbert Baake 
    Abstract: Present works research goals concern the investigation of optimal inductor design for induction heating applied to a tailored heating forging problem. The first part of this article shows the advantages of adopting a tailored inductive heating, compared to a homogeneous one. In addition to a significant simplification, results of simulation have shown that it is possible to save energy and enhance the overall efficiency. The developed model was then experimentally validated and used for a more rigorous inductor design. The aim of the second part in fact, is to perform an optimization procedure in order to design an inductor able to provide the desired tailored temperature profile.
    Keywords: Tailored heating; inductor optimal design; energy saving; induction heating; open die forging.

  • Three-criteria Numerical Optimization as a Base for Designing Induction Mass Heating   Order a copy of this article
    by Yulia Pleshivtseva, Edgar Rapoport, Paolo Di Barba, Bernard Nacke, Alexander Nikanorov, Elisabette Sieni, Michele Forzan, Sergio Lupi 
    Abstract: The work contains the results of the researches carried out by the authors during past years in the field of multiple-criteria optimization of induction heaters design based on numerical coupled electromagnetic and temperature fields analysis. The main goal of the studies is the application of different optimization methods and numerical finite element method (FEM) codes to solve the multi-criteria optimization problems formulated mathematically in terms of the typical optimization criteria: maximum temperature uniformity, minimum heating time, maximum energy efficiency and minimum scale formation. Standard genetic algorithm, non-dominated sorting genetic algorithm NSGA-II, migration NSGA algorithm, and alternance method of the optimal control theory are applied as effective optimization tools in practically oriented applications. The developed optimization procedures are planned to be used for solving the wide range of real-life problems of the optimal design and control of different induction heating devices and systems.
    Keywords: Multi-objective optimization; design; induction heating; genetic algorithm; NSGA-II; MNSGA-II; alternance method; optimal control theory.

  • Milliseconds Pulse Induction Hardening   Order a copy of this article
    by Alexandr Aliferov, Michele Forzan, Sergio Lupi 
    Abstract: Pulse induction hardening process is characterised by high power densities up to some tens of kW/cm2, heating times in the range of tens to hundreds of milliseconds and cooling rates attained by self-quenching without the use of external quenching means.
    Keywords: Induction hardening; Numerical methods; Pulse discharge.

  • Numerical modelling of industrial scale high frequency welding of cladded pipes   Order a copy of this article
    by Wladimir Ebel, Martin Kroll, Alexander Nikanorov, Egbert Baake 
    Abstract: This paper deals with induction welding of cladded pipes. Pipes for corrosive environments could be made from two materials consisting of a strong ferritic backing steel on the outside and an austenitic or nickel-based stainless steel on the inside. Due to different material properties, longitudinal HF-welding of this compound is a complex problem. A 2D simulation model was created to describe the occurring effects and is introduced in this paper. The obtained simulation results for metallurgical plated material were verified with experimental investigations on a bilayer compound. Different approaches are proposed to facilitate high frequency welding of cladded pipes under consideration of industrial requirements and capabilities.
    Keywords: cladded material welding; pipe welding; high frequency welding; induction welding; longitudinal pipe welding.

Special Issue on: Heat Treatment and Surface Engineering

    by Bojan Podgornik, Diego Ursic, Irena Paulin 
    Abstract: In recent years deep cryogenic treatment is getting increased attention in many tooling applications as a mean to improve tool performance. However, contradictory results are reported indicating improved as well as deteriorated wear resistance. The goal of this work was to investigate effect of deep cryogenic treatment on wear properties of tool steel and how they change depending on the tool steel type, and hardness and fracture toughness obtained. Results show that steel composition considerably affects the way how cryogenic treatment changes steel properties. For low carbon tool steel toughness properties can be improved for up to 70% at only minor hardness drop, but are quite limited in the case of high-speed steel, while at high carbon content both hardness and toughness are deteriorated. In general, deep cryogenic treatment was found to result in reduced abrasive wear resistance except for cases of combined hardness and fracture toughness improvement.
    Keywords: deep cryogenic treatment; wear resistance; fracture toughness; hardness; tool steel.

  • Thermal characterization of cooling power of quenchants and its influence on microstructure evolution in EN19 steels using Jominy End Quench Test Setup   Order a copy of this article
    by Vivek Tiwary, Sharaschandra Kusugal, Rahul Zajari 
    Abstract: In this study, hardenability of EN19 alloy steel has been investigated for different quenchants using a Jominy test setup. During experimentation, the temperatures were recorded using a thermocouple inserted in the specimen. Hardenability curves, cooling curves, cooling rate curves and heat flux curves were determined and are presented graphically. Microstructures were developed at various sections of the quenched specimens to study the changes in the morphology of phases. Cooling power of the quenchants has been predicted based on the hardenability curves as well as thermal characterization. It is observed that brine solution results in more heat extraction from the steel specimens compared to other quenchants. The paper aims to establish that cooling rate curves and heat flux curves determination can be a suitable technique to characterize quenchants to assess its suitability for industrial applications.
    Keywords: Jominy End Quench Test (JEQT); Hardenability; Heat Flux; Lumped Heat; EN19; Poly Alkaline Glycol (PAG).

  • Materials and Process Engineering Aspects of Warm Deep Rolling   Order a copy of this article
    by Torben Oevermann, Stephanie Saalfeld, Thomas Niendorf, Berthold Scholtes 
    Abstract: For industrial applications efficient and short processes are essential, justifying the increased complexity of deep rolling treatments at elevated temperature. For this purpose, the direct integration of deep rolling manufacturing steps in heat treatment processes is a promising strategy. Combining inductive heat treatment with deep rolling leads to encouraging results concerning near surface material states as well as resulting fatigue strengths. Different process concepts are introduced and discussed. Characteristic results of near surface microstructures and residual stress states produced in this way for steels SAE 1045 and SAE 4140 are presented. In addition, the consequences of the material states and the microstructures on cyclic deformation behavior and fatigue strength are outlined. The integrated system introduced allows the flexible application of appropriate process parameters, the analysis of their effects on the fatigue behavior and the determination of optimized process conditions.
    Keywords: Deep rolling; fatigue; mechanical surface treatment; inductive heat treatment; deep rolling at elevated temperature; residual stress.

    by Massimo Pellizzari, Faraz Deirmina 
    Abstract: Powder metallurgy permits to produce tool steels with finer microstructure and improved mechanical properties compared to wrought ones. This major advantage was recently used by the author in designing new steel grades combining higher strength and toughness. Novel hybrid tool steels, by mixing hot work and high speed steel powders in different proportions, were developed looking at materials with properties tunable for a specific application. Near ultrafine grained materials could be obtained combining mechanical milling and spark plasma sintering, a fast consolidation technique assisted by pulsed current. Particle reinforced tool steel matrix composites have also been produced using the same approach. Finally, in order to look for steels combining high hardness and improved thermal conductivity hybrid tool steel-Cu grades were sintered. The aim of present paper is to give a general overview of the research activities and the opportunities opened by these new powder metallurgy products.
    Keywords: tool steel; spark plasma sintering; ball milling; mechanical alloying.

  • Simulation of backup rolls quenching with experimental study of deep cryogenic treatment   Order a copy of this article
    by Pavel Krot, Sergey Bobyr, Maxim Dedik 
    Abstract: The research goals of this work are to simulate the phase transformations in heat treatment of large-scale rolls of special alloy steels including deep cryogenic treatment stage with experimental estimation of its influence on wear resistance of rolls. The adapted analytical models are introduced and applied for the calculation of phase transformations. Combination of finite-element models and experimental continuous cooling diagrams allowed determining the temperature and stress fields as well as each phase fraction in the special alloy steels 65Cr2Si3MoV, 50Cr5NiMoV and 70Cr3MnNiMoV at different stages of rolls manufacturing. Two short cycles of deep cryogenic treatment conducted on samples showed increased by 39% wear resistance of 65Cr2Si3MoV alloy steel compared to its standard heat treatment schedule.
    Keywords: alloy steels; quenching; FEM models; rolls; cryogenic treatment.

    by Jose L. Ocaña 
    Abstract: The current availability of lasers with characteristic pulse lengths ranging from ns to fs and the development of the appropriate laser processing workstations granting the appropriate precision and repeatability have definitively consolidated laser surface microstructuring as a reference domain nowadays unavoidable for the design and manufacturing of microsystems: MEMSs, fluidic devices, advanced sensors, biomedical devices, etc., are all among the most well-know developments of laser micromanufacturing technology. In this line, the generation of surfaces with specific functional properties is becoming an important niche of applications. In this paper, the application of laser sources with emission in the UV and at ns time regime to the surface structuration of metal surfaces (specifically Al) for the modification of their wettability properties is envisaged, the generation of superhydrophobic self-cleaning extended functional surfaces being described.
    Keywords: Laser Microstructuring; Short Pulse Lasers; Metallic Surfaces; Hydrophobicity; Self-cleaning.
    DOI: 10.1504/IJMMP.2017.10010796
  • The Application of Modern High-Energy Electron Beam Technologies   Order a copy of this article
    by Anja Buchwalder, Rolf Zenker 
    Abstract: High-energy electron beam (EB) is highly applicable for thermal processes like surface treatments, joining, ablating or for the additive manufacturing of metallic materials. Furthermore, many process-specific features may be regarded as beneficial characteristics, including the inherently high energy density and the various possibilities offered by high-speed beam deflection. The essentials of these different EB processes will be discussed and examples of applications demonstrated. The main aim of EB surface treatments is the improvement of hardness, wear and/or corrosion resistance of local functional surfaces. The EB ablating is applied for producing inserts in cast components, for improving the adherence of spray coatings on substrates or for the generation of small lubrication dimples in bearings. EB welding, may be distinguished by narrow welds with extremely high depths and mostly without filler material. The EB additive manufacturing represent future-oriented technologies for the production of complex structures in modern industrial applications.
    Keywords: electron beam; surface treatment; joining; ablating; additive manufacturing.

  • Development of Microstructure and Creep Resistance of a Martensitic Creep Resistant Steel   Order a copy of this article
    by Borut Zuzek, Bojan Podgornik, Fevzi Kafexhiu 
    Abstract: In thermal power stations, 9-12 % Cr steels are widely used for components operating at elevated temperatures. In the present work, the influence of quenching and tempering temperatures on microstructure evolution of 9-12 % Cr creep resistant steels was studied. It was found that quenching and tempering parameters influence the number, size, and mutual spacing of precipitates in the steel. The effect of different heat treatment parameters on the steady state creep rate and time to rupture showed that for the higher quenching temperature, the number of precipitates increases while their mutual spacing decreases, which leads to improved creep resistance. Effect of tempering temperatures is not so pronounced as in the case of quenching temperature.
    Keywords: austenitizing; tempering; creep resistance; mechanical properties; precipitates.

Special Issue on: News in Acoustic Emission Testing

  • Advanced Signal Analysis of Acoustic Emission Data to Discrimination of Different Corrosion Forms   Order a copy of this article
    by Luigi Calabrese, Massimiliano Galeano, Edoardo Proverbio, Domenico Di Pietro, Angelo Donato, Filippo Cappuccini 
    Abstract: The analysis of three corrosion phenomena (uniform corrosion, pitting corrosion and stress corrosion cracking) has been carried out through the use of acoustic emission technique. Corrosion attacks have been obtained on three different types of martensitic stainless steel in a FeCl3 solution, using conditions set by the ASTM G48 standard. These martensitic stainless steel used were characterized by different mechanical, microstructural and electrochemical properties, which lead to the development of specific corrosion forms, albeit the steels were tested in the same environmental conditions. A multivariate statistical analysis approach, based on PCA (Principal Component Analysis) and SOM (Self Organising Map), has been adopted to evaluate AE data and to obtain highlight damage-sensitive features. Specific clusters of variables related to specific corrosion phenomena have been identified, promoting this analysis approach as a potential procedure for discriminating onset of a specific corrosion mechanism.
    Keywords: acoustic emission; principal component analysis; uniform corrosion; localized corrosion; stress corrosion cracking,.

  • The use of b-value and Ib-value of Acoustic Emission in monitoring Hydrogen Assisted Cracking of Martensitic Stainless Steel   Order a copy of this article
    by Luigi Calabrese, Massimiliano Galeano, Edoardo Proverbio, Domenico Di Pietro, Angelo Donato 
    Abstract: Hydrogen assisted cracking phenomena in tiosulphate solution of martensitic stainless steel was investigated by using acoustic emission technique. A time domain approach was adopted in order to analyse the corrosion phenomena by acoustic emission pattern time evolution. An appropriate set of variables was used, some of them directly related to the acoustic event waveform, while others have been derived from them, such as b-value and Ib-value, that are descriptors related to the time domain distribution of the acoustic event energies. Aim of this work is to show how these two descriptors allow to obtain an easy-to-use diagnostic system for damage progression, without a deep knowledge of the acting corrosion phenomena themselves. Tests were carried out on a X12Cr13 martensitic stainless steel, according to NACE TM 0177 standard, using a modified sour simulated environment (5% NaCl, 2.5% Acetic Acid and 10-2M Na2S2O3).
    Keywords: b-value; Ib-value; acoustic emission; stress corrosion cracking; time domain series.

  • Deformation and fracture analysis of nitrided steels by acoustic emission measurement   Order a copy of this article
    by Sergey Nikulin, Anatoliy Nikitin, Vladimir Khatkevich, Stanislav Rogachev 
    Abstract: The purpose of this work is to study the processes of static tension deformation and fracture of nitrided sheet samples of 08Kh17T (type AISI 439) and 15Kh25T (type AISI 446) steels using the acoustic emission method. The nitriding was performed with pure nitrogen, at T=1000-1100
    Keywords: corrosion-resistant ferritic steel; high-temperature nitriding; tensile test; acoustic emission; deformation; fracture; strain hardening exponent.

  • Analysis of Fatigue Processes of SLM Materials by Acoustic Emission   Order a copy of this article
    by Vendula Kratochvilova, Frantisek Vlasic, Pavel Mazal, David Palousek, Libor Pantelejev 
    Abstract: The paper gives an overview of selective laser melting (SLM) materials properties focusing on fatigue processes and their acoustic emission. The selective laser melting technology belongs to rapid prototyping technologies and allows to quickly produce metal parts with complicated shapes. However the mechanical properties of these materials are currently worse than those of conventionally produced materials. Acoustic emission method was used to compare fatigue behaviour of SLM and conventionally produced materials. Tested materials were aluminium alloy AW-2618A (AlCu2Mg1,5Ni), copper alloy AMPCOLOY
    Keywords: selective laser melting; acoustic emission method; fatigue; SLM; additive technology.