Sasan Yazdani

Sahand University of Technology | SUT · Department of Materials Engineering

Selective laser melting (SLM) can induce residual stresses in components, especially those with multilayer structures and varying thermal properties. This study investigates the effect of annealing post-heat treatment on the microstructure and mechanical properties of multilayer 316L stainless steel composite reinforced with TiC particles. Three-la...

In the current research, vanadate-doped NiAl-layered double hydroxide (LDH) conversion coatings were synthesized on the anodized 2024-T4 aluminum alloy to provide efficient corrosion resistance and self-healing behavior. The effect of various pH values on the nanostructure and electrochemical behavior of synthesized coatings was investigated. Vario...

In this study, the microstructure and wear behavior of multilayer 316L stainless steel/TiC composite fabricated using selective laser melting (SLM) additive manufacturing were investigated. The produced samples consisted of three layers: 316L, 316L-5TiC, and 316L-10TiC (wt%). Microstructural evaluations revealed a homogeneous distribution of TiC pa...

The relationship between impact fracture toughness and the microstructure in a composition of nano-bainitic steel was investigated in this study. To achieve bainitic microstructures, samples were austenitized at 950 °C for 30 minutes and then austempered at 200, 250, and 300 °C for different times for completion of transformation. Mechanical proper...

This article investigates the strength and ductility properties of a low-alloy steel with a carbon content of 0.32 wt.% after performing one-, two-and three-step austempering processes. Dilatometry tests were used to extract the mandatory data for heat treatment process design, and FE-SEM and XRD were used to evaluate the microstructural characteri...

In the present study, the fracture toughness of hardened and tempered powder metallurgical (PM) high-speed steel ASP 2030 was investigated using notched and unnotched bending specimens and the finite element method. The normal flexural strength of notched and unnotched specimens marquenched by austenitizing at 1150, 1170, and 1185°C, followed by qu...

In addition to conventional isothermal heat treatment, ultrafine carbide-free bainite can be obtained by continuous annealing of steels, which is of great interest to scientists and research communities. The resulting microstructure consists of bainitic sheaves composed of bainitic ferrites interwoven with austenite films in nanoscale, being separa...

Conducting the carburizing process on the surface layer of low-carbon steel and subsequent austempering heat treatment can be implemented to obtain nanobainite microstructure on the surface of steels. In this research, steel with 0.23 wt.% carbon was carburized for 3 h at 900°C in a liquid salt bath containing sodium cyanide, sodium carbonate, and...

This study presents the fracture toughness improvement of the powder metallurgical high speed steel ASP2030 by replacing the martensitic matrix with a bainitic one. For this purpose, the fracture toughness of the steel is compared in both the austempered and marquenched states. The heat treatment of the samples was carried out by austenitizing in t...

The influence of quenching temperature on microstructural and mechanical properties of low alloy steel of the following chemical composition: 0.26 C, 1.70 Mn, 1.42 Si, 1.10 Cr, 1.10 Ni, 0.94 Cu, 0.24 Mo, 0.1 V, Bal. Fe (Wt.%) was investigated after applying a quenching-partitioning (Q-P) treatment. The steel samples were isothermally quenched at 26...

Hybrid composite coatings have distinct advantages over single composite coatings due to their multipurpose applications. Moreover, nickel-based composite coatings are widely used in corrosive and fatigue environments due to their good wear and corrosion resistance. In this study, NiCoCrAl/tungsten carbide/1-4 wt% lanthanum oxide composite coatings...

NiCoCrAl/WC + (1-4) wt.% La2O3 coatings were cladded on H13 tool steel using Nd: YAG pulsed laser. Scanning electron microscopy, wavelength dispersive X-ray spectroscopy, electron probe microanalysis, and X-ray diffraction are used to study the coatings and oxide layers. The oxidation kinetics analysis of coatings at 700 • C in a static air atmosph...

Pre-existing martensite resulted in higher strength value in nanobainitic steel. • Acceptable balance of strength-elongation-Charpy impact energy could be achieved. • Autocatalytic transformation of bainite has been observed. A R T I C L E I N F O Keywords: Nano bainitic steel Pre-existing martensite Microstructure Strength Ductility A B S T R A C...

In the current research, the effect of low-temperature calcination on the crystal structure, morphology and corrosion properties of sol-gel derived dip-coated amorphous Al 2 O 3 on plain carbon steel with a nickel elec-trodeposited intermediate layer was investigated. Alumina sol suspension was prepared via Yoldas method and modified by the additio...

It is an important challenge to reduce the carbon content in nanostructured bainitic steels for commercialization purposes while still being able to gain the desired microstructural characteristics in nanoscale and not to deteriorate the strength–ductility combinations. That is the point at which an appropriate heat treatment procedure design would...

Ausforming is being widely used to overcome the kinetics barrier in nanostructured bainitic steels and to enhance its practical industrial applications. It would also affect the microstructural characteristics and consequently the resultant mechanical performance. This article aims to investigate the tensile behaviour of nano bainite obtained from...

The potentiostatic electrodeposition of Zn−Ni−Mn was carried out in an alkaline solution with the addition of Mn salt. The effects of electrolyte Mn²⁺ concentration and deposition potential on the surface morphology, phase structure and corrosion behavior of coatings were studied. The results of corrosion polarization showed that the presence of hi...

Electroless NiP (EN) plating, as an important group of metallic coatings, is employed in a wide range of industrial applications. These coatings provide higher hardness, remarkable wear resistance and better corrosion resistance properties 1-4). However, protection against corrosion and wear can result in a variation of other properties such as fat...

The Zn-Ni-Mn/Zn–Ni multi-layer coatings were electrodeposited under switching potential regime from an alkaline solution. In order to deposit Zn–Ni layers, more positive potential −1560 mV was used as first electrodeposition potential in each cycle. More negative potentials −1860 mV and −1980 mV was used as the second potential in the various poten...

Outstanding mechanical properties of nanostructured carbide-free hard bainitic steels, also known as super bainite, with microstructural constituents of less than 100 nm thicknesses make them prone to be used in different engineering applications. However, besides their exceptional strength and ductility combinations during ordinary static or quasi...

Nanobainitic structures were produced in a low alloy carburised steel at temperatures of 200, 250 and 300°C. Scanning electron microscope micrographs indicated bainitic ferrites formed with a thickness range of 30–150 nm. Wear test results revealed that the coefficient of friction for nanobainitic samples was smaller and narrower compared to that o...

The influence of chill thickness and applied load were studied on wear behaviour of a carbidic austempered ductile iron containing Cu and Ni. Ductile iron with chemical composition Fe-3.6 C-2.6 Si-0.53 Cu-0.51 Ni (in wt.%) was cast into standard moulds with copper end chills of different thicknesses. Wear test samples were prepared from the chilled...

It is essential to produce steels free from impurities and inclusions and decrease the segregations as much as possible knowing that the quality of the primary cast steel is a very critical factor influencing its final microstructure and mechanical properties. For this aim, various refinement processes including Electro Slag Remelting (ESR) have be...

This study reveals an unprecedented capacity of flake graphene sheets in manipulating semisolid deformation of aluminium matrix nanocomposites by restricting the grain growth of the nanograins during the reheating process to significantly enhance (173%) the yield strength of the fabricated composites. The graphene sheets with onion shape have also...

The multi-step isothermal austempering heat treatment to achieve an ultra-fine bainitic microstructure and maximum volume fraction of bainite was conducted on a steel containing 0.26 wt% carbon. The microstructural and crystallographic characteristics, as well as the mechanical properties and fracture behavior were studied. The results showed that...

Electroless‐nickel plated ZrO2 (NCZ) particles have been used to produce a functionally graded nickel‐electroless‐nickel plated ZrO2 composite coating. So, electroless‐nickel plated ZrO2 particles concentration was continuously increased from 0 to an optimum value in the electroplating bath (Watt's bath). The substrate was ST37 steel and the thickn...

Terms of service of the steels with retained austenite in the microstructure, is severely depended on the stability of austenite during the course of deformation. The present work aims to evaluate the mechanical stability of austenite in nanostructured, carbide free bainitic steels during tensile testing and cold rolling process. To achieve the mic...

For the first time, functionally ZrO2 content graded Ni-ZrO2 composite coating has been successfully co-electrodeposited from a bath with gradually increasing stirring rate. For this, different composite coatings were electroplated in the same bath with different stirring rates to find the optimum stirring rate in which the maximum content with uni...

It is critical to obtain nanocrystalline materials in large chunks rather than only in thin film or rod shapes and nanostructured bainitic steels are good examples of bulk nano materials. This article aims to investigate the hardenability of nanobain steel to estimate the biggest cross section that can be successfully austempered to form nanocrysta...

For the first time, functionally electroless nickel plated ZrO2 (NCZ) graded Ni-NCZ composite coating has been successfully co-electrodeposited from a bath with gradually increasing of stirring rate. Studies showed that co-electrodeposition in a bath with stirring rate of 250 r/min results in the maximum co-electrodeposited particle content and the...

Functionally graded Ni-ZrO 2 (FGN-Z) and functionally graded Ni-NCZ (FGN-NCZ) composite coatings have been successfully co-electrodeposited from a bath containing variable concentrations of the particles. NCZ (electroless nickel coated ZrO 2) particles were manufactured by dispersing of ZrO 2 powder in an electroless-Ni plating bath. To produce fun...

Austenite films with almost identical thicknesses of nanoscale bainitic ferrite plates in a bainitic sheaf and also austenite micro blocks separating bainitic sheaves spreading in different crystallographic directions, are the main factors controlling the toughness and ductility properties in nanostructured bainitic steels. This work aims to invest...

It is crucial to eliminate the thermally and mechanically less stable austenite blocks as much as possible if enhanced mechanical properties are demanded in high performance nanostructured bainitic steels. Step-austempering would be an efficient procedure in this regard. This article aims to investigate the strength-ductility- impact toughness comb...

Metallic molybdenum coating was deposited from an aqueous electrolyte containing a high concentration of acetate and molybdate ions in pH of 6.8 ± 0.2. It is complicated to deposit molybdenum from an aqueous electrolyte because of its high reactivity with oxygen. The mole ratios of water to acetate were in the range of (2.4 ± 0.2):1. It was found t...

Terms of service of the steels with retained austenite in the microstructure, is severely depended on the stability of austenite during the course of deformation. The present work aims to evaluate the mechanical stability of austenite in nanostructured, carbide free bainitic steels during tensile testing and cold rolling process. To achieve the mic...

In this study, functionally NCZ (electroless nickel plated ZrO2) content graded Ni-NCZ composite coating has been successfully co-electrodeposited from a bath with gradually increasing of stirring rate. For this, different composite coatings were electroplated in the same bath with different stirring rates to find the optimum condition. SEM, XRD, E...

In this study, large micron-sized SiC particles were fragmented via ball-milling process in the presence of iron and nickel powders, separately, to fabricated composite powders of Fe–SiC and Ni–SiC. Continuous fracturing of brittle SiC powders leads to the formation of multi-modal-sized SiC powders with size of from 50 nm to slightly higher than 10...

Isothermal holding of high carbon steels with proper amount of alloying elements in bainitic transformation region will results in obtaining a nano bainitic structure. The structure of these steels consist of alternate layers of ferrite and high carbon austenite which their thickness are in the range of 30-150nm. These steels are not only can be pr...

Abstract: Measurements of dry sliding wear are presented for ductile irons with composition Fe-3.56C-2.67Si- 0.25Mo-0.5Cu and Ni contents of 0.8 and 1.5 in wt.% with applied loads of 50, 100 and 150 N for austempering temperatures of 270, 320, and 370 °C after austenitizing at 870 °C for 120 min. The mechanical property measurements show that the g...

Acceleration of the bainitic transformation and modifying the microstructural characteristics are believed to be of major concerns in production of Low-Temperature Bainite. Ausforming prior to isothermal bainitic transformation seems to be an effective procedure in this regard. This article aims to study the influence of different ausforming strain...

For the first time, functionally ZrO2 content graded Ni–ZrO2 composite coating has been successfully co-electrodeposited from a bath with gradually increasing stirring rate. For this, different composite coatings were electroplated in the same bath with different stirring rates to find the optimum stirring rate in which the maximum content with uni...

This study reveals a promising feature of graphene encapsulating process to significantly enhance the mutually inclusive tensile strength and ductility of aluminium based composites using the semi-solid powder forming process. It was corroborated based on van der Waals–Casimir interaction free energy that graphene sheets have an unprecedented capac...

The equilibrium partition ratio, k, has been measured for Mn, Mo, Si, Ni and Cu in a ductile iron with composition (wt.%): 3.45C, 0.25Mn, 0.25Mo, 2.45Si, 0.5Ni and 0.5Cu with different nodule counts obtained from different section sizes of 13, 25, 75 mm in the as cast, austenitized (at 870 °C for times 1, 4 and 6 hours) and austempered (at 375 °C f...

Extremely valuable mechanical properties in combination with acceptable wear resistance can make nanostructural bainitic steels to be used extensively in different engineering and tribological applications. However, it is critical to characterize the contributed factors to investigate the wear response of these high-strength materials. This work ai...

In this study, the hot extrusion process was applied to stir cast aluminum matrix-SiC composites in order to improve their microstructure and reduce cast part defects. SiC particles were ball milled with Cr, Cu, and Ti as three forms of carrier agents to improve SiC incorporation. Large brittle ceramic particles (average particle size: 80. μm) were...

Recently, valuable combinations of mechanical properties with strength of 1.9 GPa accompanied by very decent ductility of 19% and toughness of 31 J, have been achieved in a set of nanostructured bainitic steels. However, it is necessary to elucidate the significance of various microstructural features responsible of that extraordinary mechanical re...

It is well documented that much of the strength and hardness of nanostructured, carbide free bainitic steels come from the very small thickness of bainitic ferrite plates. In the current work, the Williamson-Hall method has been used to determine the bainitic ferrite plate thickness. The fitting of X-ray peaks to various functions showed good coeff...

The aim of this work is to investigate the fatigue behavior of a new class of nanostructured, low-temperature bainitic steels, where rotating bending fatigue tests were conducted on samples isothermally transformed at 300, 250, and 200 degrees C, after which, fracture surfaces were examined using scanning electron microscopy. Results showed that, f...

Understanding the main microstructural parameters that control the strength and ductility of low temperature nanostructured bainitic steels is of considerable importance for further development of these grades. The complexity of these microstructures, consisting of two phases, bainitic ferrite and retained austenite, is natural consequence of its u...

Understanding the main relationships between the microstructure parameters controlling the strength and ductility of low temperature bainitic microstructures is of considerable importance for further development of these grades. Although the microstructure essentially consists of solely two phases, bainitic ferrite and retained austenite, the compl...

The unique microstructure of nanostructured bainite consists of very slender bainitic ferrite plates and high carbon retained austenite films. As a consequence, the reported properties are opening a wide range of different commercial uses. However, bainitic transformation follows the T0 criteria, i.e. the incomplete reaction phenomena, which means...

Outstanding combination of strength and ductility in nanostructured bainitic steels makes them prone to be used as an important engineering material. However, there is still a necessity to investigate their toughness and effective parameters. This work aims to study the fracture toughness of these group of high strength carbide free bainitic steels...

Electrochemical impedance spectroscopy of Ni and Ni-ZrO2 composite coatings was studied. Investigation of corroded surfaces showed that the cluster boundaries in pure Ni and weak bonds between Ni matrix and ZrO2 particles in Ni-ZrO2 composite coating are the appropriate paths for corrosion to proceed. An equivalent circuit diagram based on blocked...

For the first time, electroless nickel plated ZrO2 (Ni-NCZ) particles were used for the co-electrodeposition of Ni-NCZ composite coating. Optical microscope, SEM and X-ray diffraction studies showed that Ni-NCZ has a rough surface with a smaller Ni crystallite size than Ni-ZrO2 due to the conductive properties of NCZ particles, which provide more n...

This study was conducted in order to investigate the influence of plastic deformation on the transformation of retained austenite in a TRIP steel with a high content of Al and a low content of Si. To the aim, appropriate treatments were used to produce the starting material (TRIP steel). The microstructure of the obtained steel was composed of b...

In the recent decade nanostructured, low temperature bainitic steels involving slender plates of bainitic ferrite (20-40 nm) with small amounts of uniformly distributed carbon enriched austenite have been developed by Bhadeshia and Caballero. For the purpose of investigation on the microstructure and mechanical properties of these steels, samples p...

Shot peening is one of the most common surface treatments to improve the fatigue behavior of metallic parts. In this study the effect of shot peening process on the fatigue behavior of an alloyed austempered ductile iron (ADI) has been studied. Austempering heat treatment consisted of austenitizing at 875° for 90 min followed by austempering at thr...

Nanostructured, low temperature bainitic steels with remarkable combination of ultimate tensile strength of about 2.5 GPa and high uniform elongation have been developed in the recent decade. To accelerate the bainitic transformation in theses steels, new chemical composition was designed by MUCG83 thermodynamic model which was developed in Cambrid...

To reduce cost production, a bainitic steel with a new chemical composition was designed using MUCG83 thermodynamic model. The steel was cast as cylinder bar using a high frequency induction furnace under argon gas atmosphere. The cast cylinder was electro-slag remelted (ESR) for obtaining clean steel. Hot rolling was carried out after ESR to reduc...

Nanostructured, low temperature bainitic steels with remarkable combination of ultimate tensile strength of about 2.5 GPa and high uniform elongation have been developed in the recent decade. To accelerate the bainitic transformation in theses steels, new chemical composition was designed by MUCG83 thermodynamic model which was developed in Cambrid...

The machinability of an austempered ductile iron with a suitable chemical composition for heavy sections has been assessed. Austempering heat treatment was carried out at three temperatures, 300, 340 and 375°C, after austenitising at 870°C for 100?min. Drilling tests, tool wear and surface roughness measurements were used to evaluate the machinabil...

Ductile irons with chemical compositions of Fe-3.6%C-2.6%Si-0.50%Cu-0.51%Ni were cast into standard keel blocks. Austenitizing heat treatment was carried out on test pieces at 875°C followed by austempering at 320, 365 and 400°C for times within the austempering processing window in a salt bath furnace. Rotating bending fatigue tests were performed...

Nanostructured, low temperature bainitic steels with remarkable combination of ultimate tensile strength of about 2.5 GPa and high uniform elongation have been developed in the recent decade. To accelerate the bainitic transformation in theses steels, new chemical composition was designed by MUCG83 thermodynamic model which was developed in Cambrid...

Bainitic transformation at low transformation temperatures leads to a microstructure involving fine plates of bainitic ferrite and thin films of retained austenite. This microstructure has shown ultimate tensile strength of about 2.2 GPa, noticeable uniform elongation in the range of 5 to 30%, hardness values of about 600 to 670 HV and impact tough...

In the recent decade, nanostructured, high carbon bainitic steels involving slender plates of bainitic ferrite with uniformly distributed carbon enriched austenite have been developed by Bhadeshia and Caballero. For the purpose of investigation on microstructure and mechanical properties of a new bainitic steel, the casting of steel was conducted u...

In the recent decade, developing of nanostructured low temperature bainitic steels with exceptional combination of ultimate tensile strength of about 2.2 GPa and respectable levels of fracture toughness have been come into attention. These steels are well comparable with maraging steels, which are at least ninety times more expensive. In this resea...

Bainitic transformation at low transformation temperatures leads to a microstructure involving fine plates of bainitic ferrite and thin films of retained austenite. This microstructure has shown ultimate tensile strength of about 2.2 GPa, noticeable uniform elongation in the range of 5 to 30%, hardness values of about 600 to 670 HV and impact tough...

The volume fraction of high carbon austenite present in the microstructure of austempered ductile iron (ADI) is one of the important factors that influence the mechanical and physical properties of the alloy. Formation of martensite by TRIP (transformation induced plasticity) mechanism during the machining operation in which a large amount of stres...

Effect of aging on the microstructure and mechanical properties of chromium-containing Fe–Ni–Mn maraging alloys was studied. An Fe–10Ni–7Mn–2Cr (wt.%) alloy exhibited strong age hardenability but suffered from premature intergranular brittleness after aging. Further chromium addition resulted in partial austenite retention in Fe–10Ni–7Mn–6Cr (wt.%)...

Effect of shot peening treatment on fatigue behavior of SAE1045 was investigated. Specimens were heat treated at 850oC for 15 minutes and then quenched in agitated oil at 60oC. Tempering treatment was done at 550oC. One group of specimens was used at this condition while other group was shot peened. The properties of tensile strength, hardness, fat...

Effects of tempering temperature and shot peening on fatigue behavior of SAE 1045 steel are reported. Tensile and fatigue property measurements are reported for samples tempered and shot peened at 300 and 550°C. Microstructural studies and fracture surface observations were carried out by optical and scanning electron microscopes. The experimental...

The effect of sub-zero cooling on microstructure and mechanical properties of a low alloyed austempered ductile iron has been investigated. Austempering of samples was performed at 325 degrees C and 400 degrees C after austenitizing at 875 degrees C and 950 degrees C. The sub-zero treatments were carried out by cooling down the samples to -30 degre...

Effects of tempering temperature on fatigue behavior of SAE1045 were investigated. Specimens were heat treated at 850oC for 15 minutes and then quenched in oil at 60oC. One group of specimens was tempered at 550oC while the second group of specimens was tempered at 300oC. The properties of tensile strength, hardness, fatigue, microstructure and fat...

Control and prediction of the dimensional changes (DC) during austempering heat treatment of ductile iron is difficult because many factors influence this behavior. In the present work cylindrical specimens of ductile iron were used to study the effect of austenitizing temperature, austempering time, temperature, and prior microstructure on DC. The...

Fatigue tests under rotating bending conditions were carried out on samples of a quenched and tempered Ck45 steel (AISI 1045) in two different conditions: (a) uncoated, (b) coated with an electroless Ni–Cu–P deposit, followed by a post-heat treatment (PHT) at 400 °C for 1 h. Such a deposit had a thickness of approximately 7 μm, with Cu and P conten...

The aim of the this investigation is to study the influence of Ni on tribiological behavior of an austempered ductile iron (ADI) containing Mo, Ni and Cu. Ductile irons with chemical composition Fe-3.56%C- 2.67%Si -0.25%Mo-0.5%Cu and Ni contents of 0.8 and 1.5% were cast into standard Y-blocks. Wear test samples were machined off from the bottom se...