Combined Effect Of Heat Treatment Research Articles

Combined effects of heat treatment and TiB2 content on the high-temperature tensile performance of TiB2-modified Ni-based GH3230 alloy processed by laser powder bed fusion

Laser powder bed fusion (LPBF) is widely used to manufacture advanced nickel-based superalloys for aero-engine components. LPBF-formed GH3230 nickel-based superalloy, however, suffers cracking and high residual stresses. This study systematically investigated the effects of different contents of submicron TiB2 particles on crack suppression and post-heat treatment for residual stress relief and improved microstructure anisotropy. The introduction of both 0.5 wt% and 1 wt% TiB2 achieved complete crack suppression in the LPBF-manufactured GH3230 specimens. As-built specimens with 0.5 wt% and 1 wt% TiB2 exhibited a supersaturated solid-solution microstructure, with the solid elements (Cr, Mo and W) almost fully dissolved in the matrix and only a limited number of Mo and Cr enriched carbides precipitated at the grain boundaries. Electron backscattered diffraction (EBSD) characterization demonstrated that a large number of deformed grains remained in the as-built specimens. After heat treatment, the residual stresses were released and the number of deformed grains significantly reduced. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) characterization demonstrated the disappearance of the dense dislocation network in the as-built specimens after heat treatment, accompanied by the precipitation of a large number of W-rich M6C carbides. This paper also discusses elevated-temperature (900 °C) mechanical properties. The ultimate tensile strength (UTS) values of the as-built GH3230 with 0.5 wt% (GH-0.5) and 1 wt% TiB2 (GH-1) specimens were 255 and 290 MPa, respectively. Compared to the as-built materials, the UTS values decreased by 40 and 53.5 MPa, respectively, after heat treatment. The paper also discusses the effect weight of the second-phase, solid-solution and dislocation-strengthening mechanisms on the elevated-temperature mechanical properties. The findings indicate that the added 1 wt% TiB2 particles and the solid-solution elements contributed about 106.2 MPa and 111.5 MPa stress, respectively, in the heat-treated GH-1 specimen. The precipitated M6C carbides after heat treatment, however, were not found to significantly improve the high temperature strength. This work is expected to provide a reference for industrial applications to improve the LPBF formability of nickel-based superalloys and to acquire attractive microstructures.

Fatigue response of additively manufactured as‐built 15‐5 PH stainless steel and effects of machining and thermal and surface treatments

AbstractAdditively produced 15‐5 PH stainless steel has wide industrial applications, but the combined effects of heat treatment, machining, and shot‐peening and their order have not been deeply investigated. This topic is addressed here by a 2‐by‐3 experimental plan that has involved S–N curve and fatigue limit determination, using vertically built cylindrical samples, tested under rotating bending. The obtained responses have been analyzed by an ANOVA‐based statistical approach for comparison of fatigue trends. Results indicate that heat treatment without machining may be even detrimental for fatigue due to embrittlement. Conversely, machining with subsequent shot‐peening, even without heat treatment, has a remarkable impact and leads to a doubled fatigue strength with respect to as‐built material. This strength is also quite close to that achievable for wrought material. The study has been completed by micrography and fractography, to reveal the dependence of microstructure, crack initiation sites, and failure mode on the performed treatments.

Effect of Citral on the Thermal Inactivation of Escherichia coli O104:H4 in Ground Beef

The objective of the present study was to analyze the combined effect of heat treatment (55 to 62.5°C) and citral (0 to 3%) on the heat resistance of Escherichia coli O104:H4 inoculated into ground beef. Inoculated meat packages were immersed in a circulating water bath stabilized at 55, 57.5, 60, or 62.5°C for various times. The surviving microbial cells were counted after culture on tryptic soy agar. A factorial design (4 × 4) was used to analyze the effects and interaction of heat treatment and citral. Heat and citral promoted E. coli O104:H4 thermal inactivation, suggesting a synergistic effect. At 55°C, the incorporation of citral at 1, 2, and 3% decreased D-values (control = 42.75 min) by 85, 89, and 91%, respectively (P < 0.05). A citral concentration-dependent effect (P < 0.05) also was noted at other evaluated temperatures. These findings could be of value to the food industry for designing a safe thermal process for inactivating E. coli O104:H4 in ground beef under similar thermal inactivation conditions.

Combined effect of heat treatment and moringa leaf extract (MLE) on colour development, quality and postharvest life of tomatoes

Combined effect of heat treatment and moringa leaf extract (MLE) on colour development, quality and postharvest life of tomatoes

Influence of pH, ionic strength and isoascorbic acid on the gel-forming ability of Jumbo squid muscle (Dosidicus gigas)

The effect of pH and ionic strength (μ) on the extraction capacity of myofibrillar proteins from Jumbo squid mantle muscle along with the addition of isoascorbic acid (IA) in its gel-forming ability (GFA) were evaluated. The results indicate that μ had a greater impact (p < 0.05) than pH on the extraction of muscle myofibrillar proteins. The effectiveness of IA, as the precursor of dehydro-isoascorbic acid (DIA), on the oxidation of sulfhydryl groups (–SH) to disulfide bonds (–SS–) of extracted proteins at 0.6 μ was also evaluated. During the sol–gel transition the –SH groups initially present in the protein system decreased (p < 0.05) due to the combined effect of heat treatment (90 °C/30 min) and the addition of IA; however, the oxidative effect of IA reduced (p < 0.05) the GFA of Jumbo squid muscle proteins. Results also indicated that NaCl at 2.8% rather than at 2.5% during gel preparation significantly (p < 0.05) improves its GFA.

Evaluating the Discharge Performance of Heat-Treated Al-Sb Alloys for Al-Air Batteries

In this work, the combined effects of heat treatment and Sb addition on the discharge performance of Al-Sb alloys as anode for Al-air batteries have been evaluated experimentally. The results indicate that heat treatment decreases the electrochemical and discharge activities of Al-Sb alloys. Heat-treated Al-Sb alloys at 550 °C for 3 h show an improved anode performance. The Al-0.02Sb alloy exhibits a high discharge capacity and anodic efficiency of 2758 Ah kg−1 and 92.6%, respectively. Further prolonging the heat treatment time results in a decrease in anode performance. Microstructure characterization indicates that such negative effect is due to the higher-temperature and prolonged heat treatment to bring out significant grain growth and coarsening of Al-Sb precipitates. The corresponding corrosion behaviors are also discussed in detail.

Combined effect of heat treatment and sealing on the corrosion resistance of reactive plasma sprayed TiNx/TiOy coatings

A titanium nitride/titanium oxide composite coating was deposited on a Q235 steel substrate by reactive plasma spraying (RPS). The microstructure and phases of the coatings were analysed by optical microscopy, scanning electron microscopy, and X-ray diffraction. The corrosion performance of the coatings was evaluated through electrochemical measurements. The as-sprayed coating is composed of TiN, TiN0.3, and Ti3O phases. Ti2O and TiO2 were generated after heat treatment at 300 and 400 °C, respectively. Heat treatment reduced the porosity of the coating. Sealing the coating before and after the heat treatment led to improved corrosion resistance. The coating heat-treated at 300 °C and then sealed had the lowest porosity (0.8%), with a reduction in porosity of 55.6% compared to that of a sealed as-sprayed coating (1.8%). The corrosion current density and corrosion potential of the sealed as-sprayed coating were found to be 6.03 × 10−7 A/cm2 and −0.47 V, respectively, whereas the coating heat-treated at 300 °C and then sealed had the lowest corrosion current density (1.8 × 10−8 A/cm2) and the highest corrosion potential (−0.19 V). Thus, the results indicate that sealed heat-treated coatings have much better corrosion resistance than the sealed as-sprayed coating.

Denaturation of collagen structures and their transformation under the physical and chemical effects

The process of denaturation of collagen structures under the influence of physical and chemical factors play an important role in the manufacture of food technology and the production of drugs for medicine and cosmetology. The paper discussed the problem of the combined effects of heat treatment, mechanical dispersion and ultrasonic action on the structural changes of the animal collagen in the presence of weak protonated organic acids. Algorithm combined effects of physical and chemical factors as a result of the formation of the technological properties of products containing collagen has been shown.

Combined effect of acetylation and heat treatment on the physical, mechanical and biological behavior of jack pine (Pinus banksiana) wood

A comparative study on the combined effect of heat treatment and acetylation on jack pine wood properties was undertaken and the results were compared with those of each treatment carried out individually. The dimensional stability and mechanical property of wood with different treatments were examined and statistically analyzed. The results demonstrated that combined acetylation of jack pine wood with acetic anhydride and heat treatment at 190 °C has a positive effect on the dimensional stability. Results also suggested that the dimensional stability was affected more than the modulus of rupture (MOR) and modulus of elasticity (MOE) by both heat and acetylation treatments under the experimental conditions used. In addition, the hardness increases after high temperature modification but decreases slightly after acetylation. A comprehensive investigation of the effects of heat treatment and acetylation separately and together (combination treatment) on the fungal durability of jack pine wood against a brown rot fungus, Poria placenta (pp), and a white rot fungus, Trametes versicolor (tv) has also been performed. The results indicated that the weight loss caused by fungi is reduced by both modifications. It was also found that combination of heat treatment and acetylation offers additional bioprotection. FTIR results indicated that the heat and acetylation treatments have a significant influence on the chemical properties, but less influence on their structures.

Study of the combined effect of electro-activated solutions and heat treatment on the destruction of spores of Clostridium sporogenes and Geobacillus stearothermophilus in model solution and vegetable puree

The combined effect of heat treatment and electro-activated solution (EAS) on the heat resistance of spores of Clostridium sporogenes and Geobacillus stearothermophilus was assessed under various heating and exposure time combinations. The acid and neutral EAS showed the highest inhibitory activity, indicating that these solutions may be considered as strong sporicidal disinfectants. These EAS were able to cause a reduction of ≥6 log of spores of C. sporogenes at 60 °C in only 1 min of exposition. For G. stearothermophilus spores, a reduction of 4.5 log was observed at 60 °C in 1 min, while in 5 min, ≥7 log CFU/ml reduction was observed. Inoculated puree of pea and corn were used as a food matrix for the determination of the heat resistance of these spores during the treatments in glass capillaries. The inactivation kinetics of the spores was studied in an oil bath. Combined treatment by EAS and temperature demonstrated a significant decrease in the heat resistance of C. sporogenes. The D100°C in pea puree with NaCl solution was 66.86 min while with acid and neutral EAS it was reduced down to 3.97 and 2.19 min, respectively. The spore of G. stearothermophilus displayed higher heat resistance as confirmed by other similar studies. Its D130°C in pea puree showed a decrease from 1.45 min in NaCl solution down to 1.30 and 0.93 min for acid and neutral EAS, respectively. The differences between the spores of these species are attributable to their different sensitivities with respect to pH, Redox potential and oxygen.

Combined effect of heat treatment and rolling on pre-strained and SPDed aluminum sheet

Specimens of pre-strained and severely deformed aluminum alloy AA1350 are undergone rolling and heat treatment at 125, 200 and 275°C on their final processing history. The combined effect of rolling and post-annealing on the mechanical properties and microstructural evolutions is investigated. The main effort is focused on the ductility of specimens tolerating duplex straining paths. Results show that adequate annealing can effectively enhance ductility without noticeable decrease in the strength of the specimens at 200°C and before recrystallization starts. During microstructural evolutions, no rapid grain/crystallite growth is observed at lower temperatures; however, treatment at 275°C considerably changes mechanical characteristics by equiaxing the lamellar structure. According to the examinations, it is concluded that pre-straining through constrained groove pressing with the strain of 1.16 and subsequently imposing rolling strain up to the strain of 1.23 results in aluminum having extremely limited ductility and ultra-fine microstructure free of micro-cracks. By annealing at 200°C, the considerable recovery of elongation (up to 4.6%) is achieved and this is noticeable compared to the ductility of non-heat treated and severely deformed aluminum (approximately 1%).

Effect of Processing on PCR Detection of Animal Species in Meat Products

Although most consumers are sensitive about the origin of the meat they consume, adulteration of meat products is not uncommon. For this reason, the development of reliable methods for animal species identification in meat products is an important research priority for food scientists. Species-specific protein- and DNA- identification methods generally used for this purpose. ELISA and protein electrophoresis are used for protein, PCR is used for species-specific DNA identification. Because DNA is known to be more resistant to processing than protein, PCR methods are generally considered as more sensitive for processed foods. However, processing conditions may also degrade DNA resulting in decreased DNA quality and yield. In this study, the individual and combined effects of heat treatment and low pH on the identification of animal species in meat products by PCR were evaluated. Beef sausage mixtures containing two different amounts of meat from a secondary species (either poultry, pork, or horse) were prepared and were subjected to heat treatment (65°C, 85°C, and 121°C) and pH adjustment (5.2 and 6.2). PCR screening for the four animal species was performed using DNA extracts of these meat samples. The results showed that, the combined effect of high temperature and low pH significantly affects the detection limit of the PCR method. Nevertheless, even low levels of adulteration can still be detected fallowing heat treatment.

TEM investigations on the effect of chromium content and of stress relief treatment on precipitation in Alloy 82

Nickel-base alloys are widely used in nuclear Pressurized Water Reactors (PWRs). Most of them have been found susceptible to Stress Corrosion Cracking (SCC) in nominal PWR primary water. The time to initiation depends on the material and is longer for weld metals than for Alloy 600. This study will focus on Alloy 82, which is used in Dissimilar Metal Welds (DMWs). In service, DMWs are either in the as-welded state or have undergone a stress relief treatment. Previous SCC studies showed that the heat treatment reduces significantly the SCC susceptibility of the weld. In this context, this study focuses on the microstructure characterization of the weld in the as-welded state and in the heat-treated state. As chromium content is also a key factor for the SCC susceptibility, welds with low chromium content and medium chromium content were studied. The lower SCC susceptibility of the heat-treated welds was attributed to intergranular Cr23C6 resulting from a combined effect of heat treatment and chromium and carbon contents. These intergranular carbides could explain the better behavior of Alloy 82, compared to other nickel-base alloys.

Combined effect of heat treatment, UV-C and superatmospheric oxygen packing on phenolics and browning related enzymes of fresh-cut pomegranate arils

Fresh-cut arils were subjected to hot water dipping at 55 °C for 30 s, UV-C light (4.54 kJ m−2) and passive modified atmosphere packaged or high oxygen (initial 90 kPa O2) active modified atmosphere packaging treatments. Arils were stored at 5 °C and 90% relative humidity up to 14 days. Superoxide dismutase, catalase, peroxidase and polyphenol oxidase activities as well as individual and total phenolics compounds and anthocyanins were assessed. All treatments reduced superoxide dismutase activity. However, UV-C and high oxygen, alone or combined, resulted in arils with the highest superoxide dismutase activity. UV-C + high oxygen treated arils also showed the lowest reduction in catalase activity. Hot water was effective suppressing polyphenol oxidase activity while peroxidase activity increased. All treatments involving high oxygen and/or UV-C kept high anthocyanins and especially phenolic content. Results showed that the decrease of superoxide dismutase and catalase and the increase in peroxidase and polyphenol oxidase might induce quality loss and browning development. The combination of UV-C and high oxygen preserved superoxide dismutase and catalase, had lower values of peroxidase and polyphenol oxidase and maintained the concentration of antioxidant compounds. These treatments seem to be a good option to improve and extend the shelf life of fresh-cut arils.

Combined effect of heat treatment and ionic strength on the functionality of whey proteins

A 5% (wt/vol) whey protein isolate (WPI) dispersion (pH 6.5) with different concentrations of NaCl was submitted to dynamic heat treatment. Protein dispersions were characterized as to their rheological properties, particle sizes, morphology, denaturation temperatures, and protein surface hydrophobicity. At low ionic strength (<200mmol/kg), gel elastic modulus increased and strongest gel stiffness was achieved. High salt concentrations lead to a weaker gel, whereas no gels at all were formed without salt. The gelation temperature was also influenced by ionic strength and an increase in denaturation temperature and thermal stability was also observed by using differential scanning calorimetry. Additionally, heat-induced changes in secondary structures upon salt augmentation were followed by Fourier transform infrared spectroscopy. Secondary structural elements estimations obtained from amide I assignments were correlated with those from amide III assignments. Upon salt increase, no differences in secondary structure were observed without heating, whereas upon heating and without salt increase, the Fourier transform infrared spectroscopy data revealed an increase in intermolecular β-sheets at the cost of β-turns and random coils, with no change in α-helical structures. However, NaCl addition along with dynamic heat treatment of WPI dispersion showed a stabilizing effect on the secondary structural elements of both amide I and amide III bands. Whey protein isolate dispersions in water were also characterized by transmission electron microscopy by a spherical shape with 2 populations (6 and 70nm). Salt increase alone resulted in the formation of denser aggregates, whereas a transition from spherical/compact protein aggregates to linear ones was observed due to combined salt/heat effect. The important size of these edifices was confirmed by microscopy and light-scattering techniques. Moreover, protein surface hydrophobicity related to the number of hydrophobic sites available decreased significantly. Finally, experimental results demonstrated the strong interaction between ionic strength and dynamic thermal treatment on protein functional properties and their careful adjustment could enable the food industry to effectively use WPI as a gelling agent.

Combined effects of heat treatment and seed layer materials on magnetic properties of CoCrPt perpendicular media

Samples of glass/Ti(20 nm)/CoCrPt (20 nm)/Ti (3.2 nm) and glass/seed (Cr or Cu)/Ti(20 nm)/CoCrPt(20 nm)/Ti (3.2 nm) were deposited by magnetron sputtering at ambient temperature or 200 °C. All samples were post-annealed at 400 °C for 15 min. For either Cu or Cr seed layer, post-annealing can enhance the out-of-plane coercivity. For post-annealed samples with either Cr or Cu seed layers, the ambient temperature growth induce an enhancement in the coercivity but a reduction in the slope of hysteresis loop at the coercivity, in comparison with that of the elevated temperature growth. With identical post-annealing and growth conditions, Cr or Cu seed layers can enhance the out-of-plane coercivity, in comparison with those grown on bare substrates. The nucleation field is negative for Cr seed layer and positive for the Cu seed layer although they have close coercivity. With the same growth and post-annealing conditions, the magnetic properties of CoCrPt layers depend on the seed layer thickness. Evolution of magnetic properties can be explained in terms of changes of structural properties of constituent layers.

Preparation of nanofiltration membranes from polyacrylonitrile ultrafiltration membranes

Polyacrylonitrile (PAN) membranes display some unusual features for ultrafiltration (UF). The meso-macropores of PAN UF membranes can be easily reduced into the range of micro-mesopores by taking advantage of surface tension forces within the capillary pores during heat treatment in the presence of ZnCl 2. Asymmetric PAN nanofiltration (NF) membranes with controlled highly dense pore surface functional groups were prepared by hydrolysis of the nitrile groups with NaOH. The combined effects of heat treatment and the presence of ZnCl 2 on the formation of nanofiltration membranes were investigated. In addition, membrane post-treatment with NaOH was studied. The effect of counterion species on the membrane performance was also investigated. A simple new method, which utilized univalent alkaline ions as probes, was developed to derive the average pore size of cationic nanofiltration PAN membranes from pure water permeability coefficients.

The effect of cold work and heat treatment on the fatigue behaviour of 3CR12 corrosion resistant steel wire

The fatigue behaviour of 3CR12 corrosion resistant steel wires has been investigated as a function of combined effects of heat treatment, such as annealing, quenching as well as mechanical treatments, such as a cold drawing. The samples were heat-treated, cold drawn and subjected to fatigue testing under load control mode. The results obtained for cold drawn 3CR12 steel wires having initial annealed microstructure, showed that the drawing strain increases both static mechanical properties and fatigue limit. Further drawing above 0.47 strain does not increase the fatigue strength significantly. However, an application of quenching treatment followed by cold drawing, improves the fatigue limit more significantly than in case where the 3CR12 steel was annealed and cold drawn. Dual-phase microstructure obtained by quenching treatment acts beneficially in terms of delaying fatigue crack initiation and propagation processes and most importantly, a notch effect on the fatigue behaviour of 3CR12 steel wires treated in this way become insignificant.

Preliminary investigation of the combined effect of heat treatment and incubation temperature on the viability of the probiotic micro‐organisms in freshly made yogurt

The combined effects of heat treatment and incubation temperature were studied on the viability and fermentation time of probiotics in ABY 1 probiotic yogurt (Lactobacillus acidophilus, Bifidobacterium spp. and yogurt bacteria). Three levels of heat treatment (85°C for 30 min, 95°C for 5 min and 95°C for 15 min) and three levels of incubation temperature (37, 40 and 44°C) were selected. At the end of fermentation, the maximum viability of probiotics (for both L. acidophilus and Bifidobacterium spp.) was observed when the milk was heated at 95°C for 15 min and incubated at 37°C. Incubation time was only affected by the incubation temperature and, at 37°C, the longest incubation time of about 6 h was needed to achieve the highest viable counts of L. acidophilus and Bifidobacterium spp.

Combined effect of heat treatment and modified atmosphere packaging on the color development of cherry tomato

Abstract Mature green cherry tomato ( Lycopersicon esculentum , cv. Coco) fruit was dipped in hot water (39 °C for 90 min) and subsequently stored in plastic films with various O 2 but similar CO 2 permeabilities at 15 °C. Changing gas composition within the films and color development of the fruit was evaluated during a storage period. Results showed that individually both the hot water dip treatment (HWT) and low O 2 modified atmosphere in films delay color development. The combination of HWT and lower O 2 had a more substantial effect in delaying color development.