Ferrite Percentage Research Articles

Improved laser surface hardening of AISI 4130 low alloy steel with electrophoretically deposited carbon coating

In the present study, the laser surface hardening of AISI 4130 was conducted using a continues wave diode laser with a maximum power of 1600 W. To improve the laser surface hardening process, carbon powder is deposited on the sample surface by electrophoretic method. By conducting laser surface hardening at the same input parameters and same heat input, the quality of the hardening is compared; cross sectional geometry of the hardened area (width, depth and entry angle of hardened), micro-hardness and the ferrite phase percentage of hardened layer. Microstructure evaluation of the laser hardened area was performed using optical microscopy. Results indicate that because of increasing the laser absorption in carbon coated samples, hardened area is larger (deeper and wider) and the value of the hardness is more than laser hardening of bare samples. Microstructure analysis indicates that transformation of the retained austenite into martensite due to the fast quenching, lead to the lower ferrite phase in martensitic structure in laser hardened layer and causes higher microhardness. Observations reveal that depth, width, and maximum hardness of laser hardening carbon coated sample without surface melting are 1.150 mm, 9.980 mm, and 762 Vickers, respectively, while for bare sample these values are 0.957 mm, 9.451 mm, and 707 Vickers, respectively. Comparing the results with the furnace hardening heat treatment show that the laser hardening process especially with carbon coated, is more effective and precise than conventional processes.

Effects of shielding gas composition on the welding stability, microstructure and mechanical properties in laser-arc hybrid welding of high nitrogen steel

This paper deals with laser-arc hybrid welding of high nitrogen stainless steel (HNS) with 1.2 mm diameter of austenitic stainless steel (ASS) filler wire. The welding was carried out with different shielding gas mixtures like 100%Ar, 95%Ar + 5%N2, 90%Ar + 10%N2, 94%Ar + 5%N2 + 1%O2 and 89%Ar + 10%N2 + 1%O2. The effects of shielding gas composition on the welding stability, microstructure and mechanical properties were analyzed. The results show that the weld seam forming and welding stability are improved when 1%O2 is added to the mixture of Ar + N2, and the nitrogen content in the weld increases significantly. The pore ratio is the lowest in 90%Ar + 10%N2 shielded weld, when 1%O2 is added to 90%Ar + 10%N2, the pore ratio increases slightly. The ferrite percentage is the lowest in 89%Ar + 10%N2 + 1%O2 shielded weld. The 89%Ar + 10%N2 + 1%O2 shielded welded joints feature better mechanical properties.

Comparative study of microwave absorption characteristics of (Polyaniline/NiZn ferrite) nanocomposites with different ferrite percentages

We present the preparation of polyaniline/Ni0.5 Zn0.5Fe2O4 (PANI/NiZn ferrite) nanocomposite. The preparation process consists of two steps: First, the ferrite is synthesized by self-combustion technique using sucrose as fuel. Then, the process is continued by in-situ chemical oxidative polymerization of aniline in the presence of the ferrite. Three different weight ratios of PANI/NiZn ferrite (1:2, 1:1, and 2:1) are prepared and structurally characterized by SEM, XRD, FT-IR and UV-vis spectroscopy. The functional characterization is performed by measuring the dc-conductivity, and microwave absorption characteristics in the range (8–12 GHz). XRD patterns prove the formation of the spinel ferrite, while SEM analysis indicates that the change in PANI/NiZn ferrite ratio has an effect on the morphology, which eventually influences the microwave absorption characteristics of the composite. A maximum reflection loss of −39.56 dB at 11.0 GHz with a matching thickness of 2.5 mm and a bandwidth of 3.0 GHz is obtained for PANI/NiZn ferrite having a weight ratio of 1:1 with only 25%w/w load in paraffin.

Optimized Magnetodielectric Coupling on High-Temperature Polymer-Based Nanocomposites

CoFe2O4 (CFO) ferrite nanoparticles with an average size of 15 nm were synthesized by a hydrothermal method and used to develop magnetodielectric (MD) composites with the piezoelectric copolyimide 2CN/0CN as polymer matrix. It is shown that the dielectric constant, dielectric loss, and saturation magnetization values of the composites increase with the increasing CFO content, being 4.4, 0.01, and 12 emu·g–1, respectively, for the sample with 20 weight percentage (wt %) of ferrite. Additionally the large MD effect response (MDE(%) = 10.15) and magnetodielectric coefficient (γ = 5.8 × 10–2) allow a new physical insight into the magneto-mechano-electrical interaction between magnetostrictive CFO and the polymer matrix. Such high MD response, the highest reported for polymer-based composite materials, can support innovative applications in the areas of sensors, actuators, and filters, among others.

Dynamic Mechanical Thermal Analysis (DMTA) of Thermoplastic Natural Rubber (TPNR) Barium Ferrite (bafe12o19) Composites

filled with 0-6 volume percentage of barium ferrite was performed using a Polymer Laboratory- Dynamic Mechanical Thermal Analyser (PL-DMTA) over a range of temperature from -100 to 100°C at 10hz. The results showed that the storage modulus (E') of the composites below the transition temperature increase with filler content up to ~3-4 volume percentage. Incorporation of the filler does not change the matrix glass transition that occurs around -40°C but the damping curve becomes broader with increasing filler content. The addition of filler in the compositedoes not affect the glass transition and melting temperature. The blend of TPNR and barium ferrite powder is only a physical mixture that does not act chemically.

Effects of Austenitizing Temperature and Cooling Rate on the Mechanical Properties of 36MnVS4 Steel for Automobile Engine Connecting Rod

The relationship between microstructure and mechanical properties of 36MnVS4 steel was studied. Different prior austenite grain sizes were obtained by austenitizing at 850, 950 and 1050 °C, respectively, and different ferrite contents were obtained by different cooling rates. Austenitizing temperature mainly influenced the grain size. With the austenitizing temperature increasing, grain size increased and the phase transformation starting temperature increased. Also, the strength increased and the plasticity and toughness decreased. Cooling rate mainly influenced the microstructure percentage. With the cooling rate increasing, ferrite percentage decreased and pearlite percentage increased. And meanwhile, the strength increased and ductility and toughness decreased. Microstructure had a significant influence on fracture splitting properties. With the grain size increasing, fracture splitting properties were markedly improved. With the ferrite percentage increasing and pearlite percentage decreasing, fracture splitting properties were worsened.

Influence of Ferrite Phase Content on the Electrochemical Properties of Duplex Stainless Steels

Duplex stainless steels have a large number of industrial applications and may replace high cost materials, especially in chloride-containing environments like seawater in off-shore platforms due to their high mechanical properties and good corrosion resistance. The influence of the ferrite content on the performance of duplex stainless steels in these corrosive environments is not well known. For the present paper, new superduplex stainless steels with ferrite between 30 and 60% were developed and their microstructure and corrosion resistance were evaluated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests in NaCl 3.5% (wt %) at 26°C and 78°C. The results obtained at 26°C showed that the pitting potential (Epitt) is little affected by the ferrite content, but for the materials with higher ferrite it was possible to observe an increase in the repassivation potential with a decrease in the corrosion potential and passive currents due to the presence of more resistive passive films. Tests performed at 78°C indicated a high decrease in the Epitt for all the samples, independently of the ferrite percentage, although maintaining superiority in higher ferrite content. Alloys with a 55% ferrite phase content, i.e. less dependent of Ni element, present a superior performance of corrosion resistance.

Effect of Continuous Annealing Temperature on Microstructure and Mechanical Properties of a High Strength Cold-Rolled DP980 Steel

Continuous annealing processes were applied to a 980MPa cold-rolled dual phase steel (Fe-0.11C-2.5Mn-0.5Si-0.4Cr) and the effect of continuous annealing temperature on microstructure and mechanical properties was investigated. The microstructures were observed and analyzed by optical microscopy (OM), scanning electron microscopy (SEM), electron probe micro-analyzer (EPMA) and transmission electron microscopy (TEM). The mechanical properties were measured by uniaxial tensile tests. The results revealed that the steel is composed of a certain percentage of ferrite, martensite and perhaps a small amount of retained austenite as well. As the annealing temperature increased, the volume fraction of martensite reached to 67% from 48% and the morphology translated to lath-like from M/A island. As a consequence, the ultimate tensile strength (UTS) and yield strength had a moderate increase from 1070 to 1110 MPa and 580 to 640 MPa, respectively. Meanwhile, the fracture elongation rose to the maximum 12.6% firstly and then decreased to about 9.0%. The optimizing mechanical properties with UTS up to 1090 MPa, yield ratio about 0.54 and fracture elongation about 13% could be obtained at the annealing temperature of 790°C for 120s.

Analisa Heat Input Pengelasan terhadap Distorsi, Struktur Mikro dan Kekuatan Mekanis Baja A36

The minimization of weld distortion has become an important subject of research in welding. Severe distortion can cause undesirable influence on the cost of fabrication since additional work or repair needs to be performed. In addition, distortion also reduce dimensional accuracy and even loss of structural integrity. The present investigation aims to reduce welding distortion on A36 steel by controlling heat input during Metal Inert Gas (MIG) welding. The welding process was carried out by maintaining constant voltage and current of 23 Volt and 145 Ampere respectively whereas travel speed was varied in the range of 3.9 to 4.9 mm/s giving heat input of 678 to 936 J/mm. Result of this investigation showed that the welding distortion was achieved at the heat input of 756 J/mm. At this heat input, the percentage of acicular ferrite is maximized resulting in good weld impact toughness.

Mechanical and moisture susceptibility properties of HMA containing ferrite for their use in magnetic asphalt

Fillers have some properties which can have a great impact on the characteristics of asphalt concrete. Several physical and chemical transactions take place among fillers and binders, which affect asphalt mix performance. Ferrites are iron magnetic oxides with other metals such as barium, strontium, manganese, nickel, and zinc which can be grouped into two soft and hard groups. Considering the small size and softness of ferrites, they can be used as fillers in asphalt mixes. In this paper, mechanical properties and moisture susceptibility of the asphalt mix containing ferrite are studied in comparison with limestone and cement filler in different combinations. The necessary samples to conduct the experiments of the Marshal resistance, indirect tensile strength (ITS) and resilient modulus (Mr) were prepared as in filler segment of the specimen, ferrite with different percentages of 0%, 35%, 70%, and 100% of the total of fillers are placed in such manner that the remaining percent in each sample was replaced once with cement filler and once with limestone filler. And thus, the seven mixtures were obtained by three filler types. According to the results, adding ferrite increased the Marshal resistance and the sample with 100% ferrite filler increased the mix resistance by 11% and 35%, respectively, compared with the samples with cement and limestone by 100%. The largest amount of ITS was for the sample with 100% ferrite filler, which compared with the sample with limestone, increased the amount of ITS by about 39% in the unconditional state and by 62% in the conditional state, indicating its higher bonding with bitumen. This sample in combination with cement also showed higher resistance than limestone. These results proved the highly effective role of active fillers in HMA mix. The impact of ferrite on asphalt mix maintenance can be found at higher ferrite percentages. This impact was observable in the chart of toughness rate of the unconditional to conditional states in a way that increased with the increase in ferrite and its amount was 7% higher in the sample with 100% ferrite filler than the samples with 100% cement and limestone filler.

Effect of B2O3 containing fluxes on the microstructure and mechanical properties in submerged arc welded mild steel plates

This paper represents a study on the effect of B2O3 additions in fluxes on the microstructure and mechanical properties of the weld metal formed during Submerged Arc Welding of Mild Steel plates. Five fluxes with about 2.5, 5, 7.5, 10 and 12.5% B2O3 were used with a low carbon electrode. Welding process parameters were kept constant for all the conditions. The microstructure of weld metal for each flux consisted mainly of acicular ferrite, polygonal ferrite, grain boundary ferrites and equiaxed pearlite. It was noted that the Vicker's hardness value was a function of boron content and shows a mixed trend. Impact Energy and Tensile Strength were increased with the increase in boron content in welds this can be attributed to relation with the higher acicular ferrite percentage. However an optimum level of toughness and tensile strength was available with 7.5% and 5% of B2O3 respectively. A qualitative comparison has also be done with fresh flux by means of full metallography and mechanically.

In situ delta ferrite estimation and their effects on FCPR at different orientations of multipass shielded metal arc welded SS304L

Solidification and re-solidification with subsequent phase transformation in different welding zones of multipass weldment play a vital role to define mechanical properties of joint structures. To avoid from penetration defects and inclusion contamination in molten metal pool, multipass shielded metal arc welding (SMAW) of SS304L is performed in this research using E308L filler metal. The objective of this research is to investigate out the multiple welding passes effects on microstructural evolution, in situ delta ferrite percentage and different mechanical properties. A metallurgical microscope is used to examine the delta ferrite phase in austenite. Instead of depending on general ferrite number (FN) obtained through rigorous physical attempts, a MATLAB® code for image processing is developed to estimate the local percentage of delta ferrite, within the austenitic phase. To reveal delta ferrite effects, its local percentage is discussed in relation to various properties. With the help of this technique, a good estimation is also made to detect the localized delta ferrite morphologies. The fusion zone (FZ) solidified in ferritic-austenitic mode (FA mode) comprises two basic delta ferrite morphologies; lacy and vermicular. Grain growth behavior and ferritic percentage of base metal (BM), heat affected zone (HAZ) and fusion zone (FZ) are discussed in single, double and triple pass weldments. Effects of delta ferrite percentage and morphology on fatigue crack initiation as well propagation are also investigated in different zones of each pass weldment. Fatigue crack propagation rate (FCPR) in different orientation with respect to welding zones is checked and it is noticed that propagation rate is much lower in perpendicular direction as compared to parallel one. Due to specific microstructural pattern, HAZ has greater fatigue crack propagation rate (FCPR) in comparison to BM and FZ. Fatigue crack propagation found highest resistant in triple pass weldment due to high concentration of lacy ferrites. However, in some cases it is found that crack mechanics is actually responsible instead of microstructural effects.

Effects of post weld heat treatment on friction welded duplex stainless steel joints

In the present work, the effects of post weld heat treatment (PWHT) on friction welded UNS S31803 duplex stainless steel samples at three different temperatures namely 1080°C, 1150°C and 1200°C followed by water quenching were studied. Microstructural evaluations such as volume fraction of austenite/ferrite, grain size measurements, SEM-EDS, TEM and microhardness aspects were carried out. The volume fraction of ferrite to austenite ratio was balanced at 1080°C. Ni element is more effective in controlling the dual phase balance. Finer grains were obtained at 1080°C due to recrystallization effect. Microhardness was affected by reduction of ferrite percentage. Dual phase presence and absence of precipitates were conformed through XRD and TEM which follow Kurdjumov–Sachs relationship. Under the following: heating pressure: 40 heating time: 4 upsetting pressure: 80 upsetting time: 2 (Experiment no. 5) on PWHT at 1080°C, the balance of dual phase ratio, finer grains and increased microhardness were obtained.

Tuning of magnetoelectric coupling in (1−y)Bi0.8Dy0.2FeO3–yNi0.5Zn0.5Fe2O4 multiferroic composites

Magnetoelectric composites (1−y)Bi0.8Dy0.2FeO3 (BDFO)–yNi0.5Zn0.5Fe2O4 (NZFO) with y=0.0, 0.1, 0.2, 0.3, 0.4, 0.5 and 1.0 are synthesized by conventional solid state reaction route. The X-ray diffraction analysis confirms the coexistence of orthorhombic perovskite BDFO and spinel NZFO phases with no third phase. Microstructural and surface morphology are studied by Field Emission Scanning Electron Microscopy. Quantitative elemental analysis of the samples is carried out by Energy Dispersive X-ray Spectroscopy. The real part of the initial permeability increases and relative quality peak broadens with the ferrite content in the composites. Dielectric constant, loss tangent, relative quality factor and ac conductivity are measured as a function of frequency at room temperature. The dielectric constant shows usual dielectric dispersion at lower frequencies due to Maxwell–Wagner type interfacial polarization. The complex impedance spectroscopy is used to distinguish between the grain and grain boundary contribution to the total resistance. The modulus study reveals the ease of polaron hopping and negligibly small contribution of electrode effect. The magnetic hysteresis has been studied to know the response of NZFO phase to the applied magnetic field in the composite. The saturation and remanent magnetization are found to increase with increase in NZFO in the composite. The magnetoelectric voltage coefficient, αME is measured as a function of applied dc magnetic field. The tuning of ferrite percentage and dc magnetic field results in highest αME (~66mV/cmOe) for the composite with 40% NZFO at 4.7kOe which is attributed to the enhanced mechanical coupling between the two phases. The incorporation of BDFO and NZFO enhances the multiferroic properties in the present composite which are quite promising from application point of view.

Magnetic cotton yarns – optimization of magnetic properties

In this paper, we present the effect of ferrite percentage content and electric current intensity passing through the electromagnet coil on magnetic properties (saturation induction, residual induction, and coercive field) of magnetic staple yarns. Also, we present a method for obtaining magnetic yarns by direct coating with magnetic powder (barium ferrite). The aim of the study is to determine the optimal processing factors that can affect the performance of magnetic characteristics using an experimental design for second-order model. The results show that an increase in ferrite percentage content is influencing the saturation and residual induction more than an increase in applied current intensity. The increase in saturation and residual induction is due to the higher content of ferrite powder from the magnetic solution that adheres on the yarn surface. The higher is the value of coercive field, the larger is the force needed to completely demagnetize the magnetic yarn.

Life prediction by ferrite–pearlite microstructural simulation of short fatigue cracks at high temperature

This paper dealt with fatigue behavior simulation based on ferrite–pearlite microstructure modeled by correctional Voronoi-polygons. The model took grain size, grain orientation and the percentage of pearlite and ferrite into consideration. The basal energy was proposed to represent the inherent energy for slip-band and grain boundary to cracking. The driving force for crack initiation and propagation caused by load condition was considered as the energy increment of slip-band and grain boundary. The fatigue behavior including crack initiation, propagation, coalescence and interference were simulated based on Monte Carlo method. The simulation results show a satisfying agreement with the experimental ones.

Investigation of Some Magnetic and Thermal Properties of $$\hbox {Epoxy/Ni}_{0.5}\hbox {Zn}_{0.5}\hbox {Fe}_{2}\hbox {O}_{4}$$ Epoxy/Ni 0.5 Zn 0.5 Fe 2 O 4 Composites

Nanoparticles of \(\hbox {Ni}_{0.5}\hbox {Zn}_{0.5}\hbox {Fe}_{2}\hbox {O}_{4}\) have been prepared by the co-precipitation method, and X-ray diffraction analysis has confirmed the formation of the desired ferrite. A pure epoxy sample and three samples of \(\hbox {epoxy/Ni}_{0.5}\hbox {Zn}_{0.5}\hbox {Fe}_{2}\hbox {O}_{4}\) composites have also been prepared with different ferrite percentages. These samples have been characterized by Fourier transform infrared spectroscopy. The magnetization of the composites has been investigated by using a vibrating sample magnetometer and has revealed that these composites may be promising candidates for electromagnetic interference suppression. Moreover, the thermal diffusivity and thermal effusivity of epoxy and composite samples have been measured by using the photoacoustic technique, where a high enhancement of the thermal diffusivity with increasing ferrite content has been observed which can be attributed to the higher number of phonon vibrational modes as well as the longer mean free path of the ferrite nanoparticles due to their crystalline structure as compared to the amorphous structure of epoxy. Moreover, the formation of a percolated network of NiZn ferrite nanoparticles inside the epoxy may enhance the phonon conduction, increasing the value of the thermal diffusivity in the bulk of the samples. On the other hand, the almost constant values of the thermal effusivity—which is a surface property—suggest that these composites may be used not only for electromagnetic interference suppression but also for thermal shielding in electronic circuits.

WEAR AND CORROSION STUDIES ON FERRITIC STAINLESS STEEL (SS 409M)

The wear and corrosion behavior of SS 409M have been evaluated and compared with Mild steel ferritic stainless steel SS 430, and austenitic stainless steel SS 304. The SS 409M is a utility grade ferritic stainless steel, and has a very low Ni percentage less than 0.30%. Annealed SS 409M contains ferrite and low percentage of tempered martensite whereas normalized SS 409M has low ferrite and higher percentage of tempered martensite. The manufacturing cost for this steel is low as compared to other grades of stainless steel but it has high strength with excellent corrosion resistance, abrasion resistance and can be easily fabricated. Thus SS 409M has been found to be a suitable material for replacing mild steel in structural applications. SS 409M has also got good wear resistance and this can be considered as an alternate material for mild steel in the railway wagons, track armor, and chemical tanks. The dry wear test has been carried out using the pin on disc machine for all the specimens. The results show that 409M has higher wear resistance as compared to mild steel and SS 430. The corrosion test has been carried out using the potentiostat for SS 409M both in annealed and in the normalized condition and the results are compared with SS 430 and SS 304. SS 304 and SS 430 stainless steels show excellent corrosion resistance while SS 409M both in annealed and in normalized condition reveal higher corrosion resistance than mild steel. Results are discussed with published work on these steels.

Microstructural Refinement and Mechanical Properties of High‐Speed Niobium‐Microalloyed Railway Wheel Steel

The relationship between microstructure and mechanical properties was studied in a Nb‐bearing high‐speed railway wheel steel and compared with a traditional low‐alloyed medium carbon steel. The microstructure of medium carbon steel comprised of ferrite and pearlite and the percentage of ferrite was increased from 4 to 24% on the addition of 0.06 wt% Nb and the grain size was refined. The addition of Nb inhibited mixed microstructure and delayed the coarsening temperature of austenite grains from 880 to 960 °C. The yield strength of Nb‐bearing steel was increased from 385 to 455 MPa and the Charpy v‐notch energy at −20 °C was increased from 7.0 to 19.0 J with no apparent reduction in tensile strength. Niobium formulates grain refinement and transformation of austenite to ferrite and pearlite over a wide region of cooling rate (<10 °C s−1) and temperature range (530–690 °C) in the medium carbon steel. With the calculation of Thermal‐Calc software and solid solubility formula, Nb exists in the form of precipitates. The grain refining and precipitation strengthening are roles of niobium in promoting ferrite–pearlite transformation and improve toughness in the medium carbon steel.

Steel Welding with Micro-Jet Injector

The article focuses on mild steel welding and covers the new possibilities of that method. Since 2011 innovate welding technology based on micro-jet cooling just after welding is being checked. Weld metal deposit (WMD) was carried out for standard MIG welding and for new welding method with micro-jet cooling. A very high percentage of acicular ferrite (AF) in WMD was gettable (55-75%) for low alloy welding with micro-jet cooling injector. This beneficial structure (very high amount of AF) is unusual to observe in WMD in other welding methods. This method is very promising mainly due to the significant improvement of weld quality and reduces costs. Furthermore impact toughness and strengths of WMD were carried out. The present paper aims at outlining same of the recent innovations in MIG welding which represent steps ahead to achieve the objectives outlined above.