International Journal of Microstructure and Materials Properties (21 papers in press)
Hot forging behavior of medium carbon and microalloyed steel: A comparative study
by Md Israr Equbal, Rajkumar Ohdar, Pinaki Talukdar, Debasis Mukerjee
Abstract: In this paper the hot forging behaviors of two grades of steel one is medium carbon and other is microalloyed with vanadium were investigated and compared with each other at the temperature of 10500C followed by cooling in normal air, forced air and quenching oil mediums. Final, microstructures and mechanical properties were evaluated by optical microscopy, charpy impact, vickers hardness, yield and tensile strength tests before and after forging up to 40% reduction on 150 ton hydraulic press. The results indicated that medium carbon microalloyed steels had higher strength and hardness compared to medium carbon steel for all cooling conditions. Oil quenching leads to a formation of relatively fine ferrite and pearlite in the commercial medium carbon steel whereas martensite, bainite with precipitation of vanadium carbides along with carbonitrides present in the matrix of ferrite- pearlite of medium carbon microalloyed steel.
Keywords: Microalloyed; Hot forging; Hydraulic press; Vanadium; Precipitation strengthening.
Effect of processing parameters on electrical properties of polypropylene/graphite composite plates
by Dedikarni Panuh, Radwan Dweiri
Abstract: This paper aims at optimizing the processing parameters for the production of electrically conductive polypropylene/graphite composite plates. The composites were prepared by melt compounding using internal mixer and the plates were produced by compression moulding. The effect of processing parameters on conductivity at different graphite contents were optimized using design of experiments based on a cross-mixed method. The results showed a significant dependence of the conductivity values on the processing parameters. The highest value of in-plane conductivity resulted from simulations was 86.83 S/cm and it was achieved at a mixing time of 57.95 min, a mixing speed of 105.8 rpm, a compression moulding time of 157.89 seconds, and a pressure of 48.24 bar. Slightly higher value of about 91 S/cm was experimentally obtained. The distribution of graphite particles and the porosity on the surfaces of plates were also examined.
Keywords: in-plane electrical conductivity; processing parameters; PP/SG composite plates; melt mixing; compression moulding; design of experiments.
A study on Microhardness and Microstructural Evolution of Titanium/Zirconium diboride Cermet Coatings with varying Scan Speeds during Laser Cladding on Ti6Al4V Substrate.
by Gabriel Farotade, Patricia Popoola
Abstract: Titanium/Zirconium diboride (Ti-ZrB2) cermet coatings were deposited at different laser scan speeds on Ti6Al4V alloy using laser cladding technique. The Microhardness of the coatings were analyzed with the aid of Vickers Microhardness tester and compared with the microhardness of the substrate, while the microstructural morphologies of the coatings were evaluated via scanning electron microscope with Energy dispersive spectroscopy (SEM/EDS). In addition the resultant grain sizes of the coatings were observed and phases formed within the coatings were also evaluated by X-ray Diffraction (XRD). With respect to the results, the microhardness of the coatings was seen to be four times harder than the substrate. SEM images exhibited a refinement in grain size and the development of distinct microstructural features. XRD patterns showed the presence of hard phases such as Al2Zr and Ti3B4 which may be responsible for the sky-rocketed microhardness values of the coatings.
Keywords: Ti-ZrB2 cermet coatings; Laser cladding technique; Laser scan speed; Ti6Al4V substrate.
Investigation on microstructure and mechanical properties on varying surface region of a service exposed IN738 turbine blade
by Lukmon Owolabi Afolabi, Puteri Sri Melor Megat Yussof, Mior Azman Meor Said
Abstract: The study investigates the micro-structural transformation and mechanical properties of nickel based IN738 super-alloy turbine blade after service exposure of 52000 hours at temperature of
Keywords: Super-alloy; Carbide decomposition; structure; grain boundary; gamma prime precipitate; tensile stress; creep properties.
Mechanical Properties and Chemical Reaction of 3-Aminopropyltriethoxysilane of Polypropylene, Recycle Acrylonitrile Butadiene Rubber, and Sugarcane Bagasse Composites
by Zainal Mustaffa
Abstract: The mechanical and chemical properties of sugarcane bagasse treated with 3-aminopropyltriethoxysilane filled polypropylene /recycled acrylonitrile butadiene rubber bio-composites were aim and investigated. The composites with different sugarcane bagasse loading from 5 to 30 wt% were prepared using heated two-roll mill by melt mixing at temperature of 180 oC. Tensile properties of composites which is tensile strength, Young Modulus and elongation at break were investigated. Increasing of treated sugarcane bagasse filler loading in composites have increased the Young modulus however decreased the tensile strength and elongation at break of the composites. The chemical properties and morphology of composites were investigated using Fourier Transform Infra-Red Analysis. These findings were supported by micrograph diagram from the morphological study. Sugarcane bagasse filler treated with 3-aminopropyltriethoxysilane has improved the adhesion and gave strong interfacial bonding between sugarcane bagasse filler and polypropylene/ recycled acrylonitrile butadiene rubber matrices which results in good tensile strength of composites.
Keywords: Mechanical Properties; Chemical Reaction; 3-aminopropyltriethoxysilane; Fourier Transform Infra-Red Analysis; Polypropylene; Acrylonitrile Butadiene Rubber; Sugarcane Bagasse; Composite.
Effect of tool rotational and transverse speed on mechanical properties of friction stir welded AA5086-H32 aluminium alloy.
by Amit Goyal, Ramesh Kumar Garg
Abstract: This research article deals with the comparative investigation of influence of process parameters on mechanical properties of AA5086-H32 aluminium alloy joints fabricated using friction stir welding. Rotational and traverse speeds of the welding tool were varied at six different levels each to carry out the study. The combination of different levels of each speed was determined by one factor at a time approach, in which one factor was varied at a time keeping another factor at its average level. The joints were inspected for visual defects like surface cracks, pin holes, tunnel defect, etc. and it was concluded that for obtaining defect free welds, rotational speed should be in the range of 1000 rpm to 1400 rpm with 60 mm/min transverse speed; and transverse speed should be in the range 60 mm/min to 110 mm/min with 1000 rpm rotational speed. The weldments were examined for mechanical properties i.e. tensile strength, percentage elongation and microhardness, and the examination showed that the joint fabricated with 1000 rpm rotational speed at 60 mm/min transverse speed was having superior weld quality.
Keywords: FSW; aluminium alloy; OFAT; tensile strength; microstructure; microhardness; rotational speed; transverse speed.
Evaluation of Internal Defects in Reinforced Concrete by Means of Innovative AE Tomography
by Takahiro Nishida, Tomoki Shiotani, Hisafumi Asaue
Abstract: The purpose of the present study is to detect the location of internal defects in reinforced concrete columns by innovative AE Tomography. The results showed that elastic wave velocity in the major part of bodies of the tested columns was lower than 2500 m/sec. Also, according to concrete core samples taken from the tested columns, elastic wave velocities of the cracked or fractured zones were lower than velocities in other zones. In addition, Concrete Quality Designation values were calculated for the concrete core sample and compared with the elastic wave velocity. As the result, the average velocity showed good correlation with Concrete Quality Designation values for the core sample. Based on the results, defects in concrete can be evaluated by means of elastic velocity distribution obtained as the result of proposed AE tomography.
Keywords: AE tomography; 3D elastic wave velocity distribution; internal defects; concrete quality designation.
Development of Cu-6Sn-5Ni-xTi and to analyze their mechanical and wear properties in as-cast condition
by Karthik. V. Shankar, Sellamuthu R, Cherian Paul
Abstract: The bronze alloys are expected to be used in bearings, bushings, propellers and wear plates in order to improve the performance in service. In order to have high service life a research was conducted to analyze the titanium effect on the mechanical and wear properties of bronze alloy. Alloys used in the present investigation were melted in an electric furnace under inert atmosphere and were cast into permanent mould. It was found that the hardness values of the alloys were observed to increase with an increase in titanium content and the wear rate values were found to decrease with an increase in the hardness and Titanium content. The coefficient of friction values for all the alloys were found to be independent of the hardness. Characterization of the alloys were conducted to study the composition and wear mechanism of the developed alloys.
Keywords: hardness; Cu-Ni-Sn-Ti; wear rate; COF; adhesive mechanism.
On the role of magnetizing frequency and magnetic field intensity on hysteresis loop characteristics
by Ashish Srivastava, Harikishor Kumar, Mohd Zaheer Khan Yusufzai, Meghanshu Vashista
Abstract: The goal of present research work is to study the variation in the shape of hysteresis loop owing to change in the analysis parameter i:e magnetizing frequency and applied magnetic field strength upon pack carburized low carbon steel samples. Pack carburized heat treatment performed at three different temperatures to induce varying hardness into steel samples. Hysteresis loop characteristics such as coercivity, permeability, power loss and remanance were measured in a wide range of magnetizing frequency and magnetic field intensity. Coercivity is observed to increase with increase in magnetizing frequency and applied field strength. In low frequency range (< 1 Hz) remanance and power loss were found to decrease, with increase in frequency in contrary increase in frequency in high frequency range (> 1Hz) results into increase in remanance and power loss. However, with increase in magnetic field strength both remanance and power loss were found to increase.
Keywords: MHysteresis loop; Magnetizing frequency; Magnetic field intensity; Coercivity; Remanance; Permeability; Power loss; Heat treatment;Microhardness.
SILICONE OIL AS CORROSION INHIBITOR FOR ALUMINIUM ALLOY IN SALINE MEDIUM
by OMOTAYO SANNI, A.P.I. Popoola, O.S.I. Fayomi, O.S. Fatoba
Abstract: Corrosion processes are responsible for huge losses in industry. This deterioration of components results in loss of plant efficiency, total shutdown and aggressive damage in industries. Though organic, inorganic and mixed material inhibitors were used for a long time to combat corrosion, the environmental toxicity of inorganic corrosion inhibitors has prompted the search for organic corrosion inhibitors. In search for this, the present study aim to investigate the inhibition action of silicone oil and their protective performance for aluminium alloy in 3.5% NaCl solution using electrochemical tests. Weight loss, corrosion rate, inhibition efficiency and potentiodynamic polarization techniques were used in this study. The aluminium alloy samples exposed to the inhibitor showed a lower corrosion rate values and excellent polarization resistance as compared with the corrosion rate samples without inhibitor. The corrosion inhibition rate increases with increasing the concentration of the silicone oil. The adsorption isotherm was confirmed by Langmuir adsorption isotherm.
Keywords: Keywords: Silicone oil; Inhibition; Corrosion; Corrosion rate and Aluminium alloy.
Special Issue on: News in Acoustic Emission Testing
Advanced Signal Analysis of Acoustic Emission Data to Discrimination of Different Corrosion Forms
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
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.
Analysis of Fatigue Processes of SLM Materials by Acoustic Emission
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.
Deformation and fracture analysis of nitrided steels by acoustic emission measurement
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.
Special Issue on: Heat Treatment and Surface Engineering
EFFECTIVENESS OF DEEP CRYOGENIC TREATMENT IN IMPROVING MECHANICAL WEAR PROPERTIES OF COLD WORK TOOL STEELS
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
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
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.
POWDER METALLURGY OPENS NEW WAYS FOR TOOL STEELS
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
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.
ROBUST GENERATION OF BIO-INSPIRED ULTRAHYDROPHOBIC METALLIC SURFACES BY NANOSECOND PULSED LASERS
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.
The Application of Modern High-Energy Electron Beam Technologies
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.