Application Of Heat Treatment Research Articles

Effects of Heat Treatment and on Magnetic Properties of NdFeB Based Permanent Magnet Alloys

In this study, the effect of flash annealing heat treatment applied at 680 oC for 5 minutes on the magnetic properties of NdFeB-based permanent magnet alloys produced by melt spinning method, which is one of the fast solidification methods, was investigated by using a very fast heating and cooling rate of 300 K/s. The obtained results showed that there was a remarkable improvement in the magnetic properties of the alloys with the applied heat treatment. Mainly, the hard magnetic properties were optimized by enhancing magnetic remanence from 21.64 emu/g to 55.76 emu/g, magnetic coercivity from 1184.15 Oe to 9146.30 Oe, and maximum energy product from 4.06 kJ/m3 to 62.02 kJ/m3 respectively.

Effect of retained austenite on the microstructure and mechanical properties of cold-rolled medium-manganese Q&P steel

ABSTRACT The effect of retained austenite stability on microstructure evolution and mechanical properties of a new cold-rolled medium-manganese steel (0.12C, 7.69Mn, 1.45Si, 2.76Al wt-%) under intercritical annealing Q&P process at different partitioning temperatures was investigated. The evolution of retained austenite was characterized and statistically analysed using SEM, TEM, EBSD, and XRD techniques. The results show that the stability of retained austenite depends to a large extent on the applied heat treatment and is mainly attributed to the retained austenite content and morphology, whose carbon content is not the main influence. More retained austenite content and the formation of heterogeneous austenite structures (granular, massive, lamellar) are observed at a partitioning temperature of 150°C. The retained austenite of different morphologies has different stabilities and can sustain the TRIP effect at different strain stages, obtaining the best comprehensive mechanical properties with 34.5% elongation and the product of tensile strength and elongation is up to 43.5 GPa·%.

Unique Anti-Corrosion Performance of Al–Mg–Si Film on Steel Plate Formed by Heat Treatment

Al–Mg–Si alloy films were formed with various intermetallic compounds of Mg, Al, and Si element by coating Mg films on a hot-dip aluminized steel plate and applying heat treatment. Various corrosion resistance evaluations were also conducted. The heat-treated Mg films showed excellent corrosion resistance compared to the non heat-treated Mg films and the hot-dip aluminized steel plate. This resulted from a delayed dissolution of the metal atoms by the potential difference between the intermetallic compounds and single metals. The heat-treated Mg film had excellent corrosion resistance with a lower corrosion current density and higher corrosion potentials compared to the non heat-treated Mg film. In particular, the corrosion delay effect was clearly confirmed in the heat-treated Mg films in the galvanic corrosion test. Based on the above results, the corrosion mechanism of the heat-treated Mg films was verified.

Farklı ısıl işlemlerin takım çeliklerinin yorulma mukavemeti üzerine etkileri

Various heat treatments are applied to improve the mechanical properties of steels depending on the intended use. In this study, the variation of fatigue strength of H13 hot work tool steel with heat treatment in a GS 550 bath was investigated. It was investigated by applying four different heat treatments as first preheating, second preheating, hardening and second hardening. Each batch of samples was subjected to rotating bending fatigue test at room temperature after heat treatment. The fatigue strength of the untreated samples was determined as 470 MPa. The fatigue strength of the second hardened untempered samples (Group 1) increased to 610 MPa. The fatigue strength of the samples (Group 2), which were annealed for two hours at 550ºC as a second heat treatment after hardening, was measured as 630 MPa. The fatigue strength of the samples (Group 3) was found to be 720 MPa by applying the third heat treatment, which was annealing at 550ºC for two hours and at 610ºC for two hours. The fatigue strength of the samples (Group 4), which were subjected to the fourth heat treatment and tempered for two hours at 550ºC and then at 635ºC for two hours after hardening, was determined as 710 MPa. It has been observed that all applied heat treatments positively affect the fatigue strength of H13 hot work tool steel. While all heat treatments resulted in increased fatigue strength, the highest fatigue strength was obtained with double annealing heat treatment (550 °C and 610 °C two hours) after initial preheating and quenching.

Duplex Heat Treatment of a Precipitation Hardening Carburising Steel

Abstract This article reports the microstructural development of a molybdenum and copper alloyed steel by different thermochemical heat treatments for gears and shafts in automotive applications. The case hardening is compared to a duplex heat treatment consisting of carburising, ageing and plasma nitriding. This study evaluates the microstructure, the surface hardness and hardness profiles. For all applied heat treatment routes, the ageing conditions have a minor influence on the case and core hardness compared to the influence of the carbon concentration. Retained austenite fractions decreased to < 5 % in all duplex heat-treated samples without cryogenic treatment. Material characterisation with optical light microscopy and scanning electron microscopy indicate unwanted phases of nitrogen and carbon-rich precipitates at the grain boundaries after duplex heat treatment. Therefore, the sequence of duplex heat treatment is changed to carburising followed by solely plasma nitriding where the unwanted precipitates are detected only up to a depth of 15‒20 μm from the compound layer.

New Results Regarding the Cavitation Destruction Behavior of Heat-Treated CuZn39Pb3 Brass with Different Parameters

Among other parts made of brass there are also the blades and the rotors of the hydraulic machines, respectively ship propellers, which during operation are degraded by cavitation erosion. As a result, most of the researches, including the most recent ones, are focused on the morphological analysis of structures eroded under the impact of micro-jets and shock waves, produced by cavitation hydrodynamics. The goal is to create new materials, but also to use new treatment technologies to increase cavitation resistance. As the literature is quite poor in studies related to the materials resistance to cavitation erosion, respectively treatments and technological procedures of it’s improvement, this paper presents the research results on the behavior of vibration cavitation erosion, carried out on three sets of CuZn39Pb3 brass samples, subjected to volumetric heat treatments of hardening for putting in solution at 800°C, followed by tempering at 250°C, 400°C and 600°C. The characterization of the behavior and the cavitation resistance of the structures resulting from the applied heat treatments is performed based on macroscopic images, taken at different representative periods, SEM images at the end of the test duration and values ​​of specific parameters recommended by ASTM G32-2016. The analysis highlights the differences caused by the change in structure by varying the temperature, but also the hardness of the surface exposed to the cavity. Thus, of the three treatments, it is found that the best resistance to cavitation is conferred by the structure resulting from hardening at 800°C, with tempering at 250°C.

Ultrahigh strength ductile microalloyed steel with a very low yield ratio developed by quenching and partitioning heat treatment

In this study, a microalloyed low carbon steel was subjected to quenching and partitioning (Q&P) heat treatment processes. The primary ferrite-pearlite microstructure of the steel was transformed into a bainitic microstructure containing interlath and sporadic blocks of retained austenite. The applied heat treatment process partitioned the carbon into the retained austenite to a weight percentage of 0.136. The microalloyed low-carbon steel acquired a continuous yield with high yield strength, a gigapascal level of ultimate tensile strength (i.e., ~ 1.1 GPa), and a very low yield ratio (i.e., 0.55) while retaining reasonable ductility and toughness when compared to the preheat-treated values.

The influence of enzymatic pretreatment of chickpea on properties of protein nanoparticles prepared by heat treatment

Protein nanoparticles from chickpea protein isolates were prepared by heat treatment and their properties were evaluated. Protein was extracted from defatted chickpea seed under alkaline conditions after pretreatment with single arabinofuranosidase or combination of cellulase and xylanase, or without it. Both enzymatic pretreatments delivered protein isolates with enhanced ratio between α-helices and β-sheets/β-strands in their secondary structure comparing to alkaline isolate. Applied heat treatment was performed for 10 min or 20 min at 90 °C, and at pH 7 or pH 9.3. Particle size of prepared nanoparticles varied from 28 to 290 nm, with the smallest particles fabricated from isolate from (cellulase + xylanase)-assisted alkaline extraction at pH 9.3. Protein isolate extracted with the assistance of arabinofuranosidase enabled preparation of nanoparticles with the highest linoleic acid binding capacity - 58% at pH 7, and 69% at pH 9.3. Generally, nanoparticles with smaller particle sizes, and higher linoleic acid binding capacity and ABTS scavenging activity were fabricated from protein extracted by enzyme-assisted alkali protocols and at higher investigated pH. Chickpea protein isolates from enzyme-assisted extractions can be great source for preparation of nanoparticles with advanced properties for the application in food sector.

A Review on Hot Stamping of Advanced High-Strength Steels: Technological-Metallurgical Aspects and Numerical Simulation

The production of ultra-high strength automotive components requires a multi-directional approach. Hot stamping combines both forming and heat treatment processes to obtain a usually martensitic structure of complicated shaped automotive parts. The preparation for production using hot stamping must involve the latest methods of numerical analysis of both temperature changes and forming, which are applied for an increasing range of materials used. In this paper, the current state of knowledge about the basics of hot stamping, used technological lines, and the current state of material used with applied heat treatments and possible coatings have been reviewed. Moreover, the numerical modeling process has been described. The most important aspects of process automation, including the use of digital twins for simulation and optimization of operational kinetics of the robots accomplishing the production process, analysis and minimization of time of production cycles, and searching for weak operational points of the control systems and for real time visualization of operation of complete line, are considered. The digital twins and corresponding numerical models enable the symmetrical design of real production lines. The details of heat treatment profiles with so called tailored zone heat treatment are provided. Hot stamping is a dynamically developing technology as evidenced by the increasing range of materials used, also from the 3rd generation of advanced high strength (AHSS) steels. It starts to combine forming of symmetric or asymmetric elements with more complex heat treatment processes as required for dual phase (DP) stainless steels or the newest generation of high-strength and ductile medium-manganese steels.

Effect of Two Soybean Varieties Treated with Different Heat Intensities on Ileal and Caecal Microbiota in Broiler Chickens.

Simple SummarySoybeans are an essential part of today’s poultry nutrition diets because of their high protein content and quality. To ensure optimum digestibility in monogastric animals, soybeans need to be thermally processed. As required heat intensities depend on individual soybean properties, the emergence of highly heterogenic soybean batches is a challenge for adequate processing conditions. Molecular changes occurring during heat treatment can alter the microbial communities colonizing the animals’ guts. Gut microbiota is of great importance for both its host animal’s performance and health. To investigate the effect of heat treatment and soybean variety on the chickens’ microbiota, two soybean varieties were selected, treated at two different heat intensities and subjected to a feeding trial. DNA was then extracted and sequenced to identify different bacterial populations in the digesta of certain gut sections. Results showed that both the soybean variety and the applied heat treatment affected the abundance of certain bacterial species in the gut of chickens, but no effect on the taxonomy level of family or genus appeared. This underlines the sensitivity and reactivity of the highly complex microbial community to apparently small dietary differences.Soybean products are of high importance for the protein supply of poultry. Heat treatment of soybeans is essential to ensure optimal digestibility because of intrinsic antinutritive factors typical for this feed category. However, excessive treatment promotes the Maillard reaction and reduces protein digestibility. Furthermore, Europe’s efforts are to decrease dependence on imports of soybean products and enlarge local production. This process will include an increase in the variability of soybean batches, posing great challenges to adequate processing conditions. Intrinsic soybean properties plus heat treatment intensity might be able to modulate the gut microbiota, which is of crucial importance for an animal’s health and performance. To assess the influence of heat treatment and soybean variety on gut microbiota, 2 soybean cakes from 2 varieties were processed at 110 °C or 120 °C and subsequently fed to 336 one-day-old broiler chickens. After 36 days, the animals were slaughtered, and the digesta of the ileum and caecum was collected. Next, 16S rRNA amplicon sequencing of the extracted DNA revealed a high discrepancy between gut sections, but there were no differences between male and female birds. Significant differences attributed to the different soybean varieties and heat intensity were detected for certain bacterial taxa. However, no effect on specific families or genera appeared. In conclusion, the results indicated the potential of processing conditions and soybean variety as microbiota-modulating factors.

The effect of ultrafast heating rate on the elemental distribution between phases in a low carbon steel

This work focuses on the effect of heating rate, i.e. conventional heating (CH) and ultrafast heating (UFH) rates on the elemental distribution between phases in a low carbon steel. Microstructural characterization was carried out using an Electron Backscatter Diffraction (EBSD) and Atom Probe Tomography (APT) technique. Nanohardness of individual microconstituents was measured. It is shown that the applied heat treatments result in the formation of multiphase microstructures consisting of a ferritic matrix with embedded martensite and retained austenite. The ferritic matrix of the CH material was fully recrystallized, whereas both recrystallized (coarser) and non-recrystallized (finer) ferritic grains were present in the matrix of the UFH material. APT analysis indirectly confirmed that recrystallized grains after both heat treatments have a lower carbon content, when the non-recrystallized grains after UFH have a higher carbon content. It correlates with the nanohardness results, i.e. non-recrystallized grains show higher hardness, while recrystallized grains have a lower hardness. The segregations of C and Mn atoms at the martensite/ferrite interface were observed after both treatments. It is hypothesized that the segregations are formed under negligible partitioning local equilibrium condition during CH, whereas the solute drag effect results in the formation of interface segregation during UFH.

Designing the microstructural constituents of an additively manufactured near β Ti alloy for an enhanced mechanical and corrosion response

Additive manufacturing of near β-type Ti-13Nb-13Zr alloys using the laser powder bed fusion process (LPBF) opens up new avenues to tailor the microstructure and subsequent macro-scale properties that aids in developing new generation patient-specific, load-bearing orthopedic implants. In this work, we investigate a wide range of LPBF parameter space to optimize the volumetric energy density, surface characteristics and melt track widths to achieve a stable process and part density of greater than 99 %. Further, optimized sample states were achieved via thermal post-processing using standard capability aging, super-transus (900 °C) and sub-transus (660 °C) heat treatment strategies with varying quenching mediums (air, water and ice). The applied heat treatment strategies induce various fractions of α, martensite (α', α'') in combination with the β phase and strongly correlated with the observed enhanced mechanical properties and a relatively low elastic modulus. In summary, our work highlights a practical strategy for optimizing the mechanical and corrosion properties of a LPBF produced near β-type Ti-13Nb-13Zr alloy via careful evaluation of processing and post-processing steps and the interrelation to the corresponding microstructures. Corrosion studies revealed excellent corrosion resistances of the heat-treated LPBF samples comparable to wrought Ti-13Nb-13Zr alloys.

Influence of Lactose on the Maillard Reaction and Dehydroalanine-Mediated Protein Cross-Linking in Casein and Whey.

A liquid chromatography–mass spectrometry method based on multiple reaction monitoring (MRM) was developed for the simultaneous quantification of markers representing two potentially competing pathways, the Maillard reaction and the dehydroalanine pathway. The two pathways involve the same residues in the proteins to some extent, namely, the essential amino acid lysine, as well as free-amino terminals available on proteins and polypeptides, competition between the two pathways in food systems may occur. The developed method comprises the following markers of the Maillard reaction: furosine, N-ε-(carboxyethyl)lysine (CEL) and N-ε-(carboxymethyl)lysine (CML), together with the dehydroalanine reaction pathway markers; lanthionine (LAN) and lysinoalanine (LAL), as well as lysine itself. The validated method was then used for the absolute quantification of heat-induced protein modifications in model systems of micellar casein and whey protein isolates (MCI and WPI, respectively) in the presence or absence of lactose. As expected, the Maillard reaction markers furosine, CEL and CML increased during the applied heat treatment in the presence of lactose, whereas the dehydroalanine markers, LAN and LAL increased with heating in both MCI and WPI, both in the presence and absence of lactose, although at lower levels in the presence of lactose, confirming the competing state of the two pathways.

Granit ve rekristalize kireçtaşı doğal taş atıklarından elde edilen kompozit malzemenin ısıl dönüşümünün incelenmesi

In this study, the usability of granite (magmatic) and recrystallized limestone (metamorphic) natural stone wastes as alternative raw materials in ceramic tile production was investigated. Based on the CaO, SiO2, and Al2O3 compounds found in waste powders, mixtures containing 65% granite and 35% recrystallized limestone (by mass) were prepared to obtain the ceramic phases of gehlenite, wollastonite and anorthite as a result of thermal transformation. The grain size of both raw materials is -149 µm (d90 = 110.957 µm). The first series samples are called natural building stone (DYT), and the second series samples, in which wood chips of 2% (by mass) -1 mm grain size are added to obtain porous material, are called natural building stone - porous (DYT-G). The samples belonging to both series was applied heat treatment at 1,160°C. Phase analysis of samples obtained after heat treatment was measured by X-Ray Diffraction (XRD) and Scanning Electron Microscope (SEM-EDS) methods, and sintering properties were measured using water absorption coefficient, flexural strength, modulus of elasticity, density-porosity and color measurement tests. Gehlenite and wollastonite phases were detected in the heat treated samples, but no anorthite phase was observed. According to the test results, it was determined that the flexural strength (22.64 MPa) of the DYT marked sample was in accordance with the ceramic tile standards. In the DYT-G example, despite the decreasing unit volume mass value, it was determined that the bending strength (16.50 MPa) was in the range of ceramic tile strength values.

Optimizing electric conductivity of innovative Al-Cu laminated composites via thermomechanical treatment

For their advantageous combinations of properties, metallic clad composites are popular in numerous commercial and industrial branches. This study deals with measurement and optimization of electric properties of innovative self-designed Al-Cu laminated composites, fabricated by the cold rotary swaging method, via thermomechanical processing. The bimetallic laminates are room-temperature swaged down to the diameter of 10 mm and subsequently subjected to two types of heat treatments, the effects of which are investigated via characterization of deformation behaviours of the component metals, structure observations, measurements of electric characteristics and microhardness. The results showed that the electric characteristics were affected not only by the grain size and preferential texture orientations, but also by the presence of bimodal grains distribution, accumulated dislocations, and twins. The highest electric conductivity (specific resistivity of 20.6 (Ωm) × 10−9) and, simultaneously, the highest hardness was observed for the sample featuring bimodal grain size, high density of dislocations, and partial structure restoration. On the other hand, the effect of the applied heat treatment was opposite, with respect to the applied temperature and reduction ratio.

Correlation between quasistatic und fatigue properties of additively manufactured AlSi10Mg using Laser Powder Bed Fusion

In order to find a resource efficient approach for the fatigue lifetime prediction of laser powder bed fusion (L-PBF) processed AlSi10Mg material, results of tensile and fatigue tests were compared. The specimens were manufactured with three different L-PBF machines and studied in different heat treatment conditions (as-built, annealed, T6 heat treated). The investigations showed that the high attainable tensile strength properties after the manufacturing process are not beneficial in the high cycle fatigue (HCF) regime. In contrast, the applied heat treatments, which lead typically to a decrease of ultimate tensile strength, improved dramatically the fatigue behavior. Additionally, a clear correlation between the elongation at fracture and HCF resistance has been found for individual heat treatment conditions. This empiric relationship provides an estimation of the fatigue resistance in the presence of material defects and can be implemented in part and process approvals.

A discussion on mechanical behaviour of Heat-Treated low carbon steel

Low carbon steel is widely used material in construction, fabrication, and automotive sectors. It possesses a good combination of strength, toughness, and hardness. However, based on the various applications, the mechanical properties can be altered by applying heat treatment techniques. In the present work, low carbon steel (with 0.18%-C) has been heat treated and analysed for its altered mechanical behaviour. Four steel samples have been taken under study- in which sample one has been used in ‘as received’ condition while other three are quenched, normalized, and annealed states respectively. Two different mechanical properties such as tensile strength and hardness have been analysed. It has been reported that the ductile behaviour of the heat-treated samples is increased. Also, the microstructural analysis, carried out through optical microscope, is in good corroboration with mechanical properties. Pearlite and cementite regions have been clearly obtained in the samples.

Investigation of consequences of violation of technology of manufacture of individ-ual elements of BMP-2 track tape

The operation of the BMP-2 infantry fighting vehicle was accompanied by periodic failures of the tracked belts. This is due to the breakage of the fixing bolts of the track pins fastening bracket, and thus the military equipment became stationary. Establishing the causes of the destruction of the bolt fixing the staple of the track fingers of the tracked belt of military equipment was carried out using a complex of instrumental materials science research. In particular, the chemical composition of the material from which the bolts and staples were made was determined by the spectral analysis; the fracture surface of the fixing bolt was investigated by the macroanalysis; the microstructure of the bolts was examined using optical microscopy; the microhardness and density of the bolt material was measured. The bolts were made from steel grades 30XM and 33XC, and not from the recommended steel grade 38XC. The macrostructure of the broken bolt corresponds to the shearing structure. The microstructure showed rolling and heat treatment defects. Density measurement confirmed the presence of heat treatment defects. The imperfection of the applied heat treatment was confirmed by measuring the microhardness. A complex of metallurgical research has established the main cause of the destruction of the bolts. It consists in an unsuccessful design of bolts and brackets, an incorrectly selected steel grade with defects in rolling and heat treatment.

Investigation of Micromechanical Properties and Tribological Behavior of WE43 Magnesium Alloy after Deep Cryogenic Treatment Combined with Precipitation Hardening.

This study investigated the micromechanical and tribological properties of WE43 alloy (Mg-Y-Nd-Zr) alloy subjected to cryogenic treatment and precipitation hardening. Microindentation tests were carried out in the range of load from 100 to 1000 mN. The introduction of deep cryogenic treatment (DCT) was shown to increase hardness and Young’s modulus, and reduce the total indentation work. As the load set during the tests increased, a gradual decrease in the measured values was observed, indicating a significant relationship between the indent size and the value of the measured parameters. Cryogenic treatment used in conjunction with precipitation hardening (after solutioning and after aging) reduces the tribological wear of the alloy. Tests have shown an almost twofold reduction in the area of the wear trace and in the volumetric wear of the alloy, as well as a more than twofold reduction in linear wear, with relatively small fluctuations in the coefficient of friction. Abrasion was the main mechanism of wear. Areas where microcutting, adhesion and plastic deformation occurred were also observed. The results indicate the significant effectiveness of the applied heat treatment in improving the service life of the WE43 alloy containing rare earth metals.

Photocatalytic activity of cobalt aluminate nanoparticles synthesized by microwave-assisted combustion method

Cobalt aluminate is one of the most widely-used spinel aluminate types. It is known that various structural, magnetic and morphological properties of spinel ceramics can vary depending on the synthesis technique and the starting chemicals used. In this study, initially, heat treatment was applied to cobalt aluminate nanoparticles synthesized by the microwave-assisted combustion method and the effects of the applied heat treatment on the structural properties were investigated. Characterization studies showed that cobalt aluminate spinel pigments were successfully synthesized. The optimum heat treatment temperature was determined as 700 °C. Then, the synthesized cobalt aluminate nanoparticles were used as photocatalysts for dye removal by photocatalytic oxidation from a synthetic wastewater containing Astrazon red textile dye and their photocatalytic activity was investigated at different catalyst dosages. Moreover, the same particles were also produced by conventional combustion technique. Then, their photocatalytic activities were studied and the data were compared with the results obtained from the experiments made with the samples produced with microwave assisted combustion method under the same experimental conditions. The results show that cobalt aluminate nanoparticles synthesized by microwave assisted combustion exhibit a better photocatalytic activity. In experiments performed with samples produced via microwave-assisted combustion method, all dyestuff content in the solution containing 50 mg/L dye was completely removed under UV irradiation for approximately 60 min. It was determined that the catalyst dosage had an effect on the reaction rate and the reaction was found to be compatible with the pseudo first order kinetic model.