Low Heat Treatment Research Articles

Effect of Low-Temperature Tempering Temperature on the Mechanical Properties of NM500 Wear-Resistant Steel

Abstract In order to explore the effect of low temperature tempering heat treatment temperatures on Brinell hardness (HB), impact absorption energy (KV2) and tensile mechanical properties of NM500 wear-resistant steel, isothermal tempering heat treatment of NM500 wear-resistant steel sheets after quenching were carried out at 200~260 °C. The microstructures, Brinell hardness, -20 °C impact energies and tensile mechanical properties of NM500 wear-resistant steel after tempered were analyzed by optical microscope, Brinell hardness tester, pendulum impact testing machine and tensile testing machine respectively. The results show that when the tempering temperature increases from 200 °C to 260 °C, the Brinell hardness of NM500 wear-resistant steel decreases from 490 HBW to 460 HBW, the offset yield strength (Rp0.2) decreases from 1396.3MPa to 1351.0MPa, and the tensile strength (Rm) decreases from 1708.5 MPa to 1615.0 MPa. However, the low temperature tempering temperature has no significant effect on the microstructure and elongation after fracture. According to GB/T 24186-2022, 200~220 °C is the suitable low temperature tempering temperature range for NM500 wear-resistant steel.

Preparation of Soft Magnetic Composite Using Cold Sintering Technique

Soft magnetic composites are powder metal products under development as an alternative to 2D laminates in electric motor applications. The 3D design of SMCs offers greater energy efficiency but poses a challenge to maintain adequate strength properties required for application. Soft magnetic composites are fabricated through compaction and heat treatment of iron particles coated with insulated coating to form a dense compact. The soft magnetic properties of the compact are affected by the properties of the iron powder, density of compact as well as the efficacy of forming uniform thin insulating coating at the particle boundary. Additionally, the strength of the compact is also affected by the nature of the insulating boundary at the particle interfaces. We report a low temperature process that involves cold sintering phenomenon to densify and strengthen soft magnetic composites. Iron powders have been modified using a co-precipitation method that forms a hydrated copper/iron oxalate coating on individual iron particles. Warm compaction of the modified iron powders at 100°C resulted in a highly dense soft magnetic composite which demonstrated ~ 3x improvement in strength. The compacts can be further heat treated in air at higher temperatures to form high strength oxide coating iron based soft magnetic composites. Results of the AC and DC magnetic measurements of fabricated cold sintered toroid compacts made as a function of heat treatment temperature reveal that DC permeability increased with heat treatment temperature. Analysis of AC core loss data showed that hysteresis power losses dominated the performance at lower heat treatment temperatures (< 300°C) beyond which dynamic core losses significantly increased.

Evidence to support phytosanitary policies–the minimum effective heat treatment parameters for pathogens associated with forest products

Research on reducing the movement of pests on wood products has led to several options for safer trade including heat treatment of wood to mitigate pests. In this study, pathogenic organisms commonly regulated in the trade of forest products were tested to determine the minimum heat dose (temperature and time) required to cause mortality. The mycelial stage of tree pathogens, Heterobasidion occidentale, Grosmannia clavigera, Bretziella fagacearum, Phytophthora cinnamomi, P. lateralis, P. ramorum and P. xmultiformis, which may be found in untreated wood products, were tested in vitro using the Humble water bath with parameters simulating the rate of heat applied to wood in a commercial kiln. RNA detection using reverse transcription real-time PCR was used to validate pathogen mortality following treatment for: P. ramorum, P. lateralis, P. cinnamomi, P. xmultiformis and G. clavigera. The lethal temperature for all pathogens ranged from 44 to 50°C for a 30-min treatment duration. Using this method to evaluate heat treatment for other forest product pests is recommended to accurately identify the minimum dose required to support phytosanitary trade. With more data potentially lower heat treatment applications may be recommended under specific conditions to produce more efficient and economical heat treatment schedules and reduce environmental impacts.

Increasing Energy Efficiency by Optimizing Heat Treatment Parameters for High-Alloyed Tool Steels

AbstractIn the paper industry, machine circular knives are used in the cutting process to provide industrial quality cuts on a variety of products. In the production of paper rolls, they cut the long-rolled paper products into commercial sizes. For this application, the high-alloyed ledeburitic cold work tool steel, DIN EN 1.2379 (X153CrMoV12; AISI D2), in the secondary hardened heat-treated condition has become the widely used industry solution. However, its heat treatment is a very energy-intensive production process. It consists of a quenching from an austenitizing temperature above 1050 °C, followed by three high-temperature tempering steps of more than 500 °C. In the study, the heat treatment process was optimized for energy efficiency, resulting in superior material properties with lower energy consumption. The most promising low energy heat treatment developed in the laboratory was reproduced in the industrial scale, and the required energy consumption was quantified. Subsequently, the resulting properties of the tools such as hardness, wear resistance and fracture toughness were determined. The energy production costs and mechanical properties of the tool steel were evaluated in comparison to conventional production methods. The newly applied heat treatment condition showed very promising and positive results in all analyzed parameters.

Role of mixed oxidant and controlled oxygen partial pressure heat treatment to regulate the dielectric properties and resistivity of SrTiO3-based CP ceramics

Sr0.99La0.01TiO3 (SLT10) colossal permittivity (CP) ceramic materials were synthesized using solid phase method and secondary heat treated using mixed oxidant 35%Bi2O3–10%Al2O3–20%MgO–25%CuO–10%SiO2 oxidant. The heat treatment atmospheres were chosen as O2, air, and Ar to correspond to different oxygen partial pressures. The dielectric properties of the Sr0.99La0.01TiO3-Percolated (SLT10-P) ceramics were investigated, and the contribution of the oxidant to the resistivity enhancement was verified by complex impedance spectroscopy and DC resistivity tests. Excellent dielectric properties were obtained for SLT10-P Air ceramic sample (16543 for dielectric permittivity and 0.016 for loss tangent), and the resistivity was increased from 2.13 × 108 Ω cm (SLT10) to 1.23 × 1011 Ω cm (SLT10-P Air). The resistance degradation mechanism of SLT10-P ceramics and oxygen vacancy migration in the process of resistance degradation were studied by using resistance monitoring device and thermally stimulated depolarization currents (TSDC) test. The introduction of oxidant optimizes the temperature stability and resistivity of SLT10 ceramics, but it will lead to the decrease of dielectric permittivity. The atmosphere of heat treatment changed the concentration of oxygen vacancy in ceramics. When SLT10-P O2 was treated in O2 atmosphere, the concentration of oxygen vacancy in ceramics decreased, which led to the decrease of dielectric permittivity and the increase of grain boundary resistance. For SLT10-P Ar ceramic, more oxygen vacancies and free electrons are induced by low oxygen partial pressure heat treatment, which enhances the dipole effect of electron pinning defects and leads to colossal dielectric permittivity, but high concentration of oxygen vacancies will affect the resistance decline. In SLT10-P Air ceramic, the coexistence of colossal permittivity and low loss tangent and high resistance is realized.

Fabrication of cold sintered soft magnetic composites using oxalate coated iron powders

The advancement of electric vehicles to replace gas-powered cars requires more efficient designs for electric motors. Three-dimensional flux motors, employing high-strength soft magnetic composites made from powdered metals, are considered a promising alternative to current state-of-the-art motors. In this study, we demonstrate that utilizing cold sintering of iron particles coated with hydrated oxalate leads to the creation of a soft magnetic composite with approximately 55 MPa of transverse rupture strength when compacted at 100 °C. Upon subsequent heat treatment up to 700 °C, the strength significantly rose to almost 219 MPa. During the heat treatment process, the oxalate undergoes transformation into iron/copper oxides. We systematically examined this chemical transformation using diffuse reflectance infrared Fourier transform spectroscopy, scanning electron microscopy, transmission electron microscopy, and electron dispersive x-ray spectroscopy. Our findings from AC and DC magnetic measurements of the cold-sintered toroid, in relation to heat treatment temperature, demonstrate an increase in DC permeability with rising heat treatment temperatures. Additionally, our analysis of AC core loss data revealed that hysteresis power losses dominate the performance at lower heat treatment temperatures (<300 °C), beyond which dynamic core losses show significant escalation.

Modified Bamboo Shoots Flour Derived from the Ampel Gading Bamboo (Bambusa vulgaris Schrad var. Striata): Physicochemical Properties and Potential Applications as a Thickening Agent

Modified flour is widely used in the food industry to enhance viscosity and texture. Previous research has investigated fermenting Bamboo Shoots Flour from Ampel Gading Bamboo which is rich in fiber. Physical process combination, like temperature changes, and chemical modifications using acids or bases, may alter the flour's gel-forming properties, thereby expanding its applications, including as a thickening agent. The objective of this study is to evaluate the physicochemical properties and potential applications of Modified Bamboo Shoots Flour (MBFS) as a thickening agent. The analysis demonstrated that MBSF comprises 28.41% carbohydrates, with 4.88% crude fiber and 18.68% starch, featuring 4.74% amylose and 13.94% amylopectin (wet basis). Additionally, it contains 28.10% protein and 11.17% fat (wet basis), maintaining the characteristic form of MBSF. Scanning Electron Microscope (SEM) evaluation revealed the presence of ovate-shaped, rough and irregular surface starch granules. Heating a 2% MBSF suspension to 100°C increases viscosity, solubility, and swelling power. Low acidity (pH 10) enhances swelling power without affecting viscosity significantly. Both low acidity and heat treatments enhance the thickening properties of the MBFS. This study offers fundamental insights into the physical and chemical characteristics of MBFS, thereby facilitating its potential application in final products.

Influence of laser powder bed fusion and ageing heat treatment parameters on the phase structure and physical behavior of Ni-rich nitinol parts

This paper examines the effect of ageing temperatures (400, 500, & 600 °C) and times (30, 60, & 90 min) on Ni-rich NiTi samples produced via the Laser Powder Bed Fusion (L-PBF) technique. Variations in the process parameters of the L-PBF which were examined included laser power at 150W and 180W, and the scanning strategy at 500 mm/s and 1000 mm/s. Ageing heat treatment enabled setting the functional properties of phase change temperatures, stress-strain response, and phase change enthalpies. Samples aged at 400 °C were found to have much higher austenitic finish temperature (40–60 °C) whereas those aged at 600 °C had near-zero or sub-zero Af temperatures. This was due to the lower nickel concentration resulting from the higher heat treatment temperature. Samples heat-treated at 500 °C exhibited Af temperature which was near to the room temperature and showed co-existence of both austenitic and martensitic phases. It was also found that the crystallite size increased from 6 to 22 nm for an ageing temperature of 400 °C, to between 38 and 48 nm for an ageing temperature of 600 °C. The highest microhardness value of 380HV was recorded from the lower heat treatment temperature and the lowest microhardness of 270HV was recorded for samples heat-treated at 600 °C. This decrease in the microhardness values is attributed to the increased crystallite size of the aged samples at higher temperatures. This work identifies for the first time the novel ability to control NiTi phase change temperature and mechanical properties using ageing heat treatments which is critical for the materials application for personalised stents. Higher heat treatment temperatures were found to lead to larger crystallite sizes.

Use of turbidimetry for determination of heat treatment intensity applied at pasteurization of milk

Express methods for estimating the intensity of heat treatment of milk are necessary in industry and in research work. For this reason, there are many ways to measure this parameter, which are based on different physical principles, including turbidimetric methods. The Harland &amp; Ashworth turbidimetric method has been developed for a long time, however, due to its high reliability and ease of implementation, it is still used in practice. However, this method has a drawback: it takes a long time to perform the analysis. In this regard, the aim of the work is to develop an express method for evaluating the thermal class of milk based on the principle of measuring the concentration of soluble whey proteins. The result is achieved through the use of a turbidimetric measurement method with optimized sample preparation parameters and parameters for measuring the optical density of a suspension of protein aggregates. The method is implemented as follows. The milk sample is mixed with 0.1 N acetate buffer (pH 4.6) in a ratio that allows to obtain a concentration of soluble milk whey proteins from 0.05% to 0.1%. Recommended dilution coefficients: 1:3 for samples of ultra-pasteurized milk and pasteurized milk with high heat treatment intensity; 1:7 for samples of pasteurized milk with low heat treatment intensity and 1:14 for raw milk samples. The solution is filtered on a membrane filter with a pore size of 0.45 microns. The resulting filtrate is mixed with 24% trichloroacetic acid (TCA) in a 1:1 ratio to coagulate soluble whey proteins and form protein aggregates. After holding for 5–10 minutes, the optical density of the suspension of protein aggregates is measured at a wavelength of 650 nm. The content of water-soluble whey proteins in the sample can be calculated according to the calibration curve. The developed method allows to obtain the measurement result in less time than the Harland &amp; Ashworth turbidimetric method.

Dissolution behavior and kinetics of the γ′ precipitates within a novel powder metallurgy Ni-based superalloy

Isothermal heat treatment experiments were used to studied the dissolution behavior and kinetics of the γ′ precipitates within the hot-extruded novel powder metallurgy Ni-based superalloy A1. The characteristics of the γ′ precipitates were accurately and rapidly extracted by deep learning methods. The JMAK models were established to predict the change of the area fraction of γ′ precipitates during heat treatment. The determination coefficient R2 of model is 0.99. The results indicate that the dissolution sequence, morphological evolution, and dissolution mechanisms of the three types of γ′ precipitates are different. The small-sized tertiary γ′ precipitates (γ′t) dissolve first, while the larger-sized primary γ′ precipitates (γ′p) dissolve last. After 15 min at 1120 °C, there were only a small amount of γ′ precipitates with 0.19 ± 0.03 % area fraction. And there was not significant changed over time. After 1 min at 1150 °C, the γ′ precipitates completely dissolved. During the process of low temperature subsolvus heat treatment (1060 °C, 1090 °C), the large-sized γ′s grown at the expense of consuming the small-sized γ′ precipitates, and the γ′s tend towards directional arrangement due to elastic interaction energy. During the subsolvus heat treatment process, the γ′p spilt due to elastic strain energy and the uneven diffusion of alloying elements, while neck-connected coalescence coarsening occurs due to the overlapping diffusion fields.

Synthesis of C3N4/rGO Composites by Low Temperature and Low Pressure Heat Treatment and Their Photocatalytic Properties

Synthesis of C3N4/rGO Composites by Low Temperature and Low Pressure Heat Treatment and Their Photocatalytic Properties

The influence of the HIP process on the microstructure, critical temperature and critical current density of double-doped (with Dy2O3 + C, and Tb2O3 + C) MgB2 bulk compounds

ABSTRACT We present the results of the irreversibility field (B irr ), critical temperature (T c), and magnetic critical current density (J cm) for cylindrical samples encapsulated in carbon and doped with 1-3 at% dysprosium and terbium oxides. All samples were analyzed microstructurally by using a scanning electron microscope (SEM) and X-ray diffraction (XRD). The influence of annealing temperature and time and high isostatic pressure on J cm was investigated. Our results show that double-doped (C + Tb2O3 and C + Dy2O3) and low isostatic pressure heat treatment (0.1 MPa) decrease the T c by about 0.5 K compared to the undoped MgB2 (0.1 MPa). The magnetic measurements show that double-doped and heat treatment under high isostatic pressure (HIP - 1 GPa) leads to a decrease in T c of about 2.5 K compared to the undoped MgB2 sample after the HIP process. Our results show that the HIP process slightly increases J cm at 4.2 K and 20 K, and improves J cm at 30 K in undoped MgB2 samples. Furthermore, our results show that the HIP process and double-doped significantly increase J cm at 4.2K and decrease J cm at 30K. Our results indicate that the HIP process can produce high field and low-temperature pinning centers in doubly doped MgB2 materials.

Synthesis of Sb-doped Li10P3S12I solid electrolyte and their electrochemical performance in solid-state batteries

The glass-ceramic Li10P3S12I solid electrolyte exhibited moderate ionic conductivity of ∼3 mS cm−1, but it shows low interface stability with lithium, poor moisture stability, and the electrochemical performance is not well established with respect to lithium. In this work, we enhance the ionic conductivity, interface stability, and air stability using Sb-substitution in Li10P3S12I glass-ceramic solid electrolyte using a high-energy ball milling process followed by a low heat treatment process. The ionic conductivity analysis reveals that the prepared Li10.1P2.95Sb0.05S12I glass ceramic composition shows a higher ionic conductivity of 5.9 mS cm−1 at 25 °C than Li10.1P2.95Sb0.05S12I (5.06 mS cm−1). The Li10.1P2.95Sb0.05S12I glass ceramic symmetric cell exhibits a better critical current density of 1 mA cm−2 than bare (0.7 mA cm−2). Also, it demonstrates better DC cyclability at 0.25 mA cm−2 without internal short circuits after 80 cycles. The Sb-substitution not only enhanced the ionic conductivity, also increased the moisture stability according to HSAB theory. The lithium solid-state battery is constructed using the Li10.1P2.95Sb0.05S12I electrolyte that demonstrates a high discharge capacity of 146 mAh g−1 at 0.1C rate than bare electrolyte (126 mAh g−1).

Synthesis of mace silver nanorod with particles and water-alcohol room-temperature-curing UV conductive ink

At present, the silver nanorods of UV conductive ink have the problems of easy agglomeration of silver nanorods, and slow curing speed. In this paper, firstly mace-like silver nanorods with inorganic particles were synthesized by using polycarbonate fibers as soft-templates, AgNO3 as silver source. The diameters and lengths of silver nanorods were 0.25–0.35 μm and 2.1–5.1 μm. There are many wolf-tooth particles (0.20–0.35 μm) on the silver nanorods which prevented the silver nanorods from reuniting. The obtained silver nanorods were not easy to agglomerate. The minimum resistance value of the coating could reach 1∼10Ω. Secondly, a kind of water-alcohol UV conductive ink with low heat treatment temperature (140 °C), fast drying and curing speed and water-alcohol system was prepared. Water-alcohol soluble P(AA-r-HEMA)-g-GMA was used as the prepolymer, glycidyl triethylenetetraamine hexamethacrylate (TGMA) was used as the monomer, and 907 and ITX were used as photoinitiators. The effects of the types and contents of different photoinitiators (907:1%–5%, ITX: 0.2 %∼1 %), species and contents of prepolymer (30 %∼50 %), the number and content of monomers with different functional groups (30 %∼50 %) on the UV-curing rate were studied. The curing rate was the fastest when the mass fraction of photoinitiator ITX was 0.4 %, the mass fraction of the prepolymer with 30 % GMA content was 50 % and the mass fraction of monomer TGMA was 50 %. The curing speed can reach 2–3 s, and the ink film surface was smooth without bubbles. At last, UV conductive ink was prepared by using the obtained water-alcohol UV curing system as the bonding material and mace-like silver nanorods as the conductive filler. The influence of heat treatment temperature and time on the conductive properties of the coating was explored. The optimal heat treatment temperature was 140 °C, and the heat treatment time was 30 min.

Investigation of deformation mechanisms in Hastelloy X superalloy manufactured via laser powder-bed fusion: Insights into effects of carbides and cellular structure at elevated temperatures

Hastelloy X (HX) is an important nickel-based superalloy used to manufacture heat-resistant components for aerospace engines. To understand the failure mechanisms of laser powder-bed fusion (LPBF)-manufactured HX (LPBF HX) at high temperature, the effects of carbides and cellular structures on the stress rupture life of LPBF HX at 815 °C are investigated. Different heat treatment conditions, including 1100 °C solution treatment (ST1100) and 1180 °C solution treatment (ST1180, which involves the standard heat treatment temperature), as well as the as-built state, are implemented to control the carbides and recrystallization degree. The stress rupture life of the ST1100 specimen is three times longer than that of the ST1180 specimen. Coarsened carbides are formed at the grain boundaries of the ST1100 specimen during the stress rupture test, which restrained wedge-shaped cracks. In addition, the cellular structure of the ST1100 specimen contributes to both continuous dynamic recrystallization and discontinuous dynamic recrystallization at high temperatures, thus providing additional plastic deformation ability. Therefore, a lower heat treatment temperature leads to better stress rupture performance of the LPBF HX because of the combined effect of the larger carbide size and cellular structures.

Investigating Heat-Treatment Effects on Biodegradable Banana Peel Plastic Manufacturing Processes

Traditional petroleum-based plastic takes hundreds of years to degrade, and so it is accumulating at an alarming rate, while plastic consumption is also increasing exponentially. Global plastic contamination has been the most threatening environmental issue globally since it is a staple in everybody's lives. So, an urgent method must be created to minimize the usage of conventional non-biodegradable plastics. In this study, banana peel plastic models shaped as rods, beads, and films were created first and subjected to four different heat-treatment methods: two with a low-heat treatment of 80℃ and 65℃ 24 hours with a fanning function in a dehumidifier, while high-heat treatments of 120℃, 1 or 2 hours in an electric oven. The study's results suggested that the banana plastic created with the low-heat treatment 80℃ presents more favorable qualities in molding weight change, pressing hardness, tensile force, and water stability. The stability in the pH solution was more excellent in low-heat treated plastic than in high-heat treated plastic. More studies might be needed to clarify the causes of differences in the characteristics examined.

Effect of dipotassium phosphate addition and heat on proteins and minerals in milk protein beverages

Our objective was to determine the effects of dipotassium phosphate (DKP) addition, heat treatments (no heat, high temperature, short time [HTST]: 72°C for 15 s, and direct steam injection UHT: 142°C for 2.3 s), and storage time on the soluble protein composition and mineral (P, Ca, K) concentration of the aqueous phase around casein micelles in 7.5% milk protein-based beverages made with liquid skim milk protein concentrate (MPC) and micellar casein concentrate (MCC). Milk protein concentrate was produced using a spiral wound polymeric membrane, and MCC was produced using a 0.1-µm ceramic membrane by filtration at 50°C. Two DKP concentrations were used (0% and 0.15% wt/wt) within each of the 3 heat treatments. All beverages had no other additives and ran through heat treatment without coagulation. Ultracentrifugation (2-h run at 4°C) supernatants of the beverages were collected at 1, 5, 8, 12, and 15-d storage at 4°C. Phosphorus, Ca, and K concentrations in the beverages and supernatants were measured using inductively coupled plasma spectrometry. Protein composition of supernatants was measured using Kjeldahl and sodium dodecyl sulfate-PAGE. Micellar casein concentrate and MPC beverages with 0.15% DKP had higher concentrations of supernatant protein, Ca, and P than beverages without DKP. Protein, Ca, and P concentrations were higher in MCC supernatant than in MPC supernatant when DKP was added, and these concentrations increased over storage time, especially when lower heat treatments (HTST or no heat treatment) had been applied. Dipotassium phosphate addition caused the dissociation of αS-, β-, and κ-casein, and casein proteolysis products out of the casein micelles, and DKP addition explained over 70% of the increase in supernatant protein, P, and Ca concentrations. Dipotassium phosphate could be removed from 7.5% of protein beverages made with fresh liquid MCC and MPC (containing a residual lactose concentration of 0.6% to 0.7% and the proportional amount of soluble milk minerals), as these beverages maintain heat-processing stability without DKP addition.

Structure and magnetic properties of [formula omitted] bioactive glass-ceramic system for magnetic fluid hyperthermia application

Ferrimagnetic glass-ceramics comprising maghemite crystals were synthesized for magnetic fluid hyperthermia (MFH) usage. The present work is focused on the result of the chemical composition and heat treatment temperature on the magnetic behavior of (60−x)SiO2−(10+x)FeO−20CaO−10Na2O,0≤x≤30 glass-ceramic system. It was observed that with the increasing of FeO from 10 to 40 wt% in the glass-ceramic compound, the percentage of maghemite phase increased. It was also seen that in the low heat treatment temperature (680 °C), by adding iron oxide up to 30 wt%, iron cations acts as a network former, and more than this amount acts as a network modifier. In contrast, iron cations in the same composition range at high temperatures (840 °C), acts as a network modifier. According to the VSM results, the maximum magnetization of glass-ceramics incremented from 0.23 emu/g to 0.30 emu/g with the increase in FeO percentage. It was also observed that with the increment of iron oxide percentage, the morphology of maghemite crystals changed from spherical to dumbbell-shaped.

Effect of low magnetic field heat treatment process on grain sizes and soft magnetic properties of Finemet cores

In this study, we investigate the effect of low transverse magnetic field annealing on the soft magnetic properties of cores made of industrial Finemet ribbons. The variation of static/dynamic magnetic properties and average grain size of the cores obtained by zero-field annealing (ZFA), secondary-field annealing (SMA) and direct-field annealing (DMA) are studied in detail. It is found that the average grain size obtained by DMA decreased compared to that of the ZFA sample, while the average grain size increased slightly after SMA. The effective permeability (μe) of the ZFA sample after SMA decrease less than that of the ZFA sample with increasing frequency. The μe of the DMA sample decreases significantly at the low-frequency stage but tends to decrease smoothly overall, maintaining high effectiveness at high frequencies magnetic permeability. For example, at 100 kHz, the μe of ZFA at 550 °C temperature is only 0.6 × 104, while the μe of SMA and DMA are 2.0 × 104 and 2.2 × 104, respectively. Meanwhile, the Hc = 1.85 A/m, Br = 0.59 T after ZFA and Hc = 1.67 A/m after DMA show no significant decrease compared to ZFA. While Hc = 0.55 A/m, Br = 0.08 T after SMA. Due to the field anisotropy constant Ku generated after SMA and DMA, the average anisotropy constant is dominated by Ku, the domain structure becomes simple and uniform, and the domain width becomes larger. This leads to a decrease in core losses with increasing frequency and improves the high-frequency characteristics of the core. These results can provide good guidance for performance optimization for Finemet alloys in a wide frequency range.

Laser metal deposition of low carbon 410L stainless steel and heat treatment

Additive manufacturing (AM) of 410L ferritic/martensitic stainless steel via laser metal deposition (LMD) process is investigated. The carbon content of 410L powder used is low at 0.004 wt%. Heat treatment is utilized to study the microstructure and mechanical properties evolution of the deposited material. The microstructure of as-built low carbon 410L includes equiaxed ferrite phase, widmanstatten ferrite, martensite, and (Fe,Cr)23C6 nanoprecipitates. After heat treatment at 1000 °C for 10 min, refined equiaxed grains and high fraction of martensitic phase are formed. The yield strength is 601.9 MPa for as-built condition and 930.6 MPa for heat-treated condition (1000 °C/10 min); the ultimate tensile strength (UTS) is 923.0 MPa for as-built condition and 1101.5 MPa for the heat-treated condition (1000 °C/10 min); the elongation is 17.7% for as-built condition and 15.1% for the heat-treated condition (1000 °C/10 min). The low carbon 410L fabricated using LMD shows a better combination of high strength and good ductility compared with 12Cr stainless steels with higher carbon contents fabricated using conventional processes. This study provides a benchmark of 410L stainless steel fabricated using fusion-based metal AM process.