Heat Treatment Treatment Research Articles

Numerical and experimental studies on the effect of cryogenic treatment on welding residual stress of TIG welded EN8 steel plate

Most of the conventional welding process induces Welding Residual Stress (WRS), hydrogen embrittlement and distortions to welded components. The post-weld mechanical behaviour has an impact on both structural integrity and operational effectiveness of the welded component. Traditional Post Weld Heat Treatment (PWHT) is capable of relieving WRS to some extent. Based on recent research, Heat Treatment (HT) cycles are comprised of conventional HT and Cryogenic Treatment (CT) gives better fatigue life to welded components by redistributing the residual stress field. There is a need for further research to explore the impact of different parameters of CT affects the mechanical behaviour of welded specimens. In this study, numerical and experimental investigations are conducted to understand the impact of HT cycles comprised of austenitizing, quenching, CT and tempering process, over the TIG welded EN8 plates. Numerical model is developed for predicting the variation in WRS with each stage of HT cycles and observed a considerable redistribution of WRS after the completion of proposed HT cycle. Using the proposed HT cycle, the influence of different soaking periods of CT over the welded components are studied experimentally and shows that 36 hours soaking period have higher impact on the welded component’s mechanical behaviour.

Effect of post-deposition heat treatments on the microstructure and tensile properties of wire-fed electron beam directed energy deposition GH4169 Ni-based alloy

The microstructure and tensile properties of GH4169 alloy fabricated by wire-fed electron beam directed energy deposition (EB-DED) were investigated in both as-deposited (As-Dep) and homogenization plus double aging heat treatment (HA) condition. The results show that thermal cycling caused an aging effect in the As-Dep samples, resulting in the precipitation of the γ’/γ” phases in close proximity to the Laves phase. The dissolution behavior of Laves phase in GH4169 alloy at various homogenization heat treatment temperatures and holding times was studied. Based on experimental results and Johnson-Mehl-Avramie-Kolmogorov (JMAK) analysis, the dissolution activation energy of Laves phase was calculated as 218.2 kJ/mol. The heat treatment regime utilized in HA treatment consisted of 1150 °C × 60 min/WC + 720 °C × 8 h/FC to 620 °C × 8 h/WC. After HA treatment, most of the Laves phases were dissolved and the γ’/γ” phases were precipitated. The mechanical properties of HA samples are superior to those of As-Dep samples. The morphology, distribution and evolutionary mechanism of the Laves phase, γ’/γ” phases are discussed and analyzed.

Microbial inactivation of pressure spray combined with high-voltage electrospray and its application in honey raspberry juice

Pressure spray combined with high-voltage electrospray (PS-ES) has garnered considerable interest as a novel, non-thermal approach for microbial inactivation and preservation of liquid food. This study compared PS-ES with heat treatment (HT) to understand its inactivation mechanism against E. coli and S. aureus in a simulated system. Microbial activity, cell permeability, membrane integrity, membrane potential, and cell membrane structure were assessed. Furthermore, the impact of PS-ES treatment on microbial activity and flavor in honey raspberry juice, was examined. The changes in microbial growth and color during storage were also discussed. The experimental findings revealed that PS-ES treatment effectively reduced the number of E. coli and S. aureus by 1.99 and 1.83 log colony-forming units (CFU/mL). Additionally, it disrupted the integrity of bacterial cell membranes increasing their permeability, which led to the release of cellular proteins and nucleic acids. PS-ES treatment lowered the membrane potential and altered the structure of bacterial proteins. Application of PS-ES in honey raspberry juice reduced bacterial counts from 4.48 log CFU/mL to 1.99 log CFU/mL, with less flavor deterioration compared to HT treatment. After 30 days of storage at 4 °C and room temperature, PS-ES effectively controlled the growth of microorganisms in raspberry juice and maintained the color of the juice.

Enhancing the mechanical properties and surface morphology of individualized Ti-mesh fabricated through additive manufacturing for the treatment of alveolar bone defects.

Titanium meshes are widely utilized in alveolar bone augmentation, and this study aims to enhance the properties of titanium meshes through heat treatment (HT) and the synergistic finishing technology of electric field and flow field (EFSF). Our findings illustrate that the titanium mesh exhibits improved mechanical properties following HT treatment. The innovative EFSF technique, in combination with HT, has a substantial impact on improving the surface properties of titanium meshes. HT initiates grain fusion and reduces surface pores, resulting in enhanced tensile and elongation properties. EFSF further enhances these improvements by significantly reducing surface roughness and eliminating adhered titanium powder, a byproduct of selective laser melting printing. Increased hydrophilicity and surface-free energy are achieved after EFSF treatment. Notably, the EFSF-treated titanium mesh exhibits reduced bacterial adhesion and is non-toxic to osteoblast proliferation. These advancements increase its suitability for clinical alveolar bone augmentation.

Thermal Treatment and High-Intensity Ultrasound Processing to Evaluate the Chemical Profile and Antioxidant Activity of Amazon Fig Juices

The present paper evaluated the influence of heat treatment (HT) and high-intensity ultrasound (HIUS) on the chemical profile of the Amazon fig (Ficus subapiculata, Moraceae) juices. Antioxidant activity, quantification of carotenoids, total phenolic compounds (TPC), pH, titratable acidity, soluble solids, color and chemical profile (NMR) were evaluated. Treatments did not change the pH (3.4–3.5), titratable acidity (0.044–0.048%) and soluble solids (2.3–2.4 °Brix). The highest antioxidant activity (DPPH, ABTS) and TPC were presented by the HT-treated juice, which was equivalent to 1235 ± 11 µM TE, 1440 ± 13 µM TE and 312 ± 5 mg GAE mL−1, respectively. The treatments influenced the color luminosity according to the L* and a* parameters, while the b* parameter showed no significant change. The L* parameter was elevated in all treated samples compared to the control sample. Analyzing the parameter a* f, it was verified that the sample with thermal treatment (HT) was different from the control sample, but presented similarity with the samples of the HIUS processes. The 1H NMR spectra of the juices showed similar chemical profiles in all treatments. The compounds α-glucose, β-glucose, fructose, citric, malic, quinic, and p-hydroxybenzoic acids were identified. The HT treatment presented higher efficiency to extract the antioxidant compounds from fig juices. The HIUS treatments with constant energy density also improved the tolerance of the antioxidant compounds, especially in conditions of higher potency and reduced time. Future studies will be devoted to carry out microbiological analysis and evaluate the stability of treated juices.

Comparison between heat treatment and SPS treatment on CoCrFeMnNi/WC coatings

ABSTRACT In this study, spark plasma sintering (SPS) was used for the thermoelectric composite treatment of CrMnFeCoNi/WC plasma transfer arc welding (PTA) coating to explore the difference compared with common heat treatment (HT). X-ray diffraction (XRD) was used to detect the phase composition, and a combination of scanning electron microscopy (SEM) and transmission electron microscopy (TEM) was used to characterize the microstructure. The performance of nano-indentation was tested. The results show that the coating after PTA has a large dislocation density due to internal stress, while HT and SPS treatment significantly reduce the internal stress and dislocation density of the coating. Nano-indentation test shows that the hardness of the coating after PTA is 4.24 GPa, and after HT, the hardness decreases to 4.05 GPa. However, the coating after SPS treatment has significant precipitation-strengthening effect due to the wide existence of the precipitated phase, and the hardness rises to 4.78 GPa.

Effects of ultrafiltration combined with high‐pressure processing, ultrasound and heat treatments on the quality of a blueberry–grape–pineapple–cantaloupe juice blend

SummaryThis study investigated the effect of ultrafiltration (UF) combined with high‐pressure processing (HPP) at 550 MPa, 25 °C for 5 min, ultrasound (US) at 520 W, 40 °C for 10 min and heat treatment (HT) at 90 °C for 3 min on the microbial, physicochemical and sensory properties of a blueberry–grape–pineapple–cantaloupe juice blend during 104 days of storage at 4 °C. After UF, the shelf life of the HPP‐ and US‐treated clear juice blends were 104 and 72 days during the storage at 4 °C respectively. HPP, US and HT treatment minimally affected the anthocyanin and total phenol contents, while HPP better maintained the ascorbic acid levels and sensory properties in the clear juice blend during the storage. Therefore, HPP combined with UF was identified as a prospective processing technique in the fruit juice industry.

Effects of heat treatment combined with laser shock peening on wire and arc additive manufactured Ti17 titanium alloy: Microstructures, residual stress and mechanical properties

Wire and arc additive manufactured (WAAM) metal parts usually contain large columnar grains and detrimental tensile residual stress, affecting their mechanical performance. In this work, a post-treatment method combining heat treatment (HT) and laser shock peening (LSP) was employed to alter the microstructure and mechanical properties of WAAM Ti17 titanium alloy. The results show severe plastic deformation was induced in the surface layer, which, in turn, led to a high-level surface compressive residual stress (~−763 MPa) by combination treatment of HT and LSP. Meanwhile, high-density dislocations and mechanical twins were observed in coarse α phases after treatment by laser shock wave, and gradually evolved into refined α phases. The elongation of samples was significantly improved by 15% while ensuring original ultimate tensile strength (UTS, 1153 ± 13 MPa) after HT and LSP treatment. This combined HT and LSP method helps enhance the mechanical performance of WAAM parts through changing their microstructure and residual stress distribution.

Effect of post-treatments on microstructure and mechanical properties of a novel nickel-based powder metallurgy superalloy processed by selective laser melting

A newly developed third generation nickel-based powder metallurgy (PM) superalloy, designated as FGH100L, was produced through Selective Laser Melting (SLM). Post-treatments, including Heat Treatment (HT), Hot Isostatic Pressing (HIP) and combined HIP + HT treatment, were carried out on the as-SLMed alloy to improve its mechanical properties by controlling the microstructure and/or reducing the defects in the alloy. Both HT and HIP treatments facilitated the recovery and recrystallization of the superalloy, especially when the solution temperature reached 1150 °C, thereby homogenizing the microstructure and refining the grains. During the post-treatment, the number density of γ′ precipitates increased obviously with the process varying from SLM, SLM + HIP, SLM + HT to SLM + HIP + HT, and both yield strength and ultimate strength increased accordingly, indicating that the precipitation strengthening played a major role in improving the alloy strength. During the HIP process, the size and quantity of the pores were greatly reduced, which contributed greatly to a much higher elongation of the SLM + HIP alloy than that of the SLM and SLM + HT alloys. The fracture surfaces of the SLM alloys after different post-treatments showed transgranular fracture features, while the intergranular fracture was the main fracture mode of the as-SLM alloy.

EjHAT1 Participates in Heat Alleviation of Loquat Fruit Lignification by Suppressing the Promoter Activity of Key Lignin Monomer Synthesis Gene EjCAD5.

Texture attributes such as firmness and lignification are important for fruit quality. Lignification has been widely studied in model plants and energy crops, but fruit lignification has rarely been investigated, despite having an adverse effect on fruit quality and consumer preference. Chilling-induced loquat fruit lignification that occurs after harvest can be alleviated by heat treatment (HT) applied prior to low temperature storage. Enzyme activity assay showed that HT treatment could retard the low temperature-induced increase in cinnamyl alcohol dehydrogenase (CAD) activity. Transcript analysis and substrate activity assays of recombinant CAD proteins highlighted the key role of EjCAD5 in chilling-induced lignin biosynthesis. A novel homeobox-leucine zipper protein ( EjHAT1) was identified as a negative regulator of EjCAD5. Therefore, the effect of HT treatment on lignification may be partially due to the suppression of the EjCAD5 promoter activity by EjHAT1.

Chronic whole-body heat treatment relieves atherosclerotic lesions, cardiovascular and metabolic abnormalities, and enhances survival time restoring the anti-inflammatory and anti-senescent heat shock response in mice

Unhealthy lifestyle persistently feeds forward inflammation in metabolic organs thus imposing senescence-associated secretory phenotype (SASP), as observed in obesity and type 2 diabetes. However, SASP blocks physiological resolution of inflammation by suppressing the anti-inflammatory and anti-senescent heat shock (HS) response, i.e., the gene program centered in heat shock factor-1 (HSF1)-dependent expression heat shock proteins (HSPs). As SASP-inducing factors are not removed, leading to the perpetuation of inflammation, we argued that SIRT1-HSF1-HSP axis might also be suppressed in atherosclerosis, which could be reversible by heat treatment (HT), the most powerful HS response trigger. LDLr−/− adult mice were fed on high-fat/high-cholesterol diet from the age of 90 days until the end of study (age of 270 days). After 120 days under atherosclerotic diet, the animals were submitted to either whole-body HT (n = 42; 40 °C) or sham (n = 59; 37 °C) treatment (15 min/session), under anesthesia, once a week, for 8 weeks, being echographically and metabolically monitored. Aortic expressions of SIRT1, HSF1, HSP27, HSP72 and HSP73 were progressively depressed in atherosclerotic animals, as compared to normal (LDLr+/+; n = 25) healthy counterparts, which was paralleled by increased expression of NF-κB-dependent VCAM1 adhesion molecule. Conversely, HT completely reversed suppression of the above HS response proteins, while markedly inhibiting both VCAM1 expression and NF-κB DNA-binding activity. Also, HT dramatically reduced plasma levels of TG, total cholesterol, LDL-cholesterol, oxidative stress, fasting glucose and insulin resistance while rising HDL-cholesterol levels. HT also decreased body weight gain, visceral fat, cellular infiltration and aortic fatty streaks, and heart ventricular congestive hypertrophy, thereby improving aortic blood flow and myocardial performance (Tei) indices. Remarkably, heat-treated mice stopped dying after the third HT session (= 8 human years), suggesting a curative effect. Therefore, evolution of atherosclerosis is associated with suppression of the anti-inflammatory and anti-senescent SIRT1-HSF1-HSP molecular axis, which is refreshed by chronic heat treatment.

Involvement of PAL, C4H, and 4CL in Chilling Injury-induced Flesh Lignification of Loquat Fruit

Loquat (Eriobotrya japonica) is a model fruit for investigating flesh lignification during storage and response to chilling injury. However, the investigations of enzymes and coding genes and loquat fruit lignification under low-temperature storage are still limited. Here, the activity and transcript levels of up-stream enzymes of the phenylpropanoid pathway, including l-phenylalanine ammonia-lyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate:coenzyme A ligase (4CL), were investigated. The results indicated that activity of these enzymes was positively correlated with loquat fruit lignification and suppression of these increases by heat treatment (HT) and low-temperature conditioning (LTC) significantly alleviated loquat fruit lignification. Coding genes for these enzymes were subsequently isolated based on information from an RNA-seq database and expression of Ej4CL1 was found to be the most responsive to low temperature and inhibition by HT and LTC treatment, whereas the other genes were less responsive to these treatments. Furthermore, function of Ej4CL1 was analyzed by transient overexpression in tobacco leaves, where it stimulated lignin accumulation. Ej4CL1 may be a key candidate that involved in CI-related loquat fruit lignification.

Deficiency in the Heat Stress Response Could Underlie Susceptibility to Metabolic Disease.

Heat treatment (HT) effectively prevents insulin resistance and glucose intolerance in rats fed a high-fat diet (HFD). The positive metabolic actions of heat shock protein 72 (HSP72), which include increased oxidative capacity and enhanced mitochondrial function, underlie the protective effects of HT. The purpose of this study was to test the ability of HSP72 induction to mitigate the effects of consumption of a short-term 3-day HFD in rats selectively bred to be low-capacity runners (LCRs) and high-capacity runners (HCRs)—selective breeding that results in disparate differences in intrinsic aerobic capacity. HCR and LCR rats were fed a chow or HFD for 3 days and received a single in vivo HT (41°C, for 20 min) or sham treatment (ST). Blood, skeletal muscles, liver, and adipose tissues were harvested 24 h after HT/ST. HT decreased blood glucose levels, adipocyte size, and triglyceride accumulation in liver and muscle and restored insulin sensitivity in glycolytic muscles from LCR rats. As expected, HCR rats were protected from the HFD. Importantly, HSP72 induction was decreased in LCR rats after only 3 days of eating the HFD. Deficiency in the highly conserved stress response mediated by HSPs could underlie susceptibility to metabolic disease with low aerobic capacity.

Optical studies of defects generated in neutron‐irradiated Cz‐Si during HP‐HT treatment

AbstractNeutron‐irradiated Czochralski grown silicon subjected to heat treatment (HT) at 350 °C and 1000 °C under enhanced hydrostatic pressure (HP) was studied in this work. It has been shown that external hydrostatic pressure enhances the creation of VO2 defects in neutron irradiated silicon subjected to the HP ‐ HT treatment at 350 °C. Enhanced formation of platelet‐like oxygen precipitates was found in the samples treated at 1000 °C under 1.1 GPa. This effect was more pronounced in the samples with VO2 defects. Presented results seem to suggest that probably HP helps to transform VO2 to some kind of defects or change alone VO2 defects in the form that can act as an additional nucleus for an additional oxygen precipitation at 1000°C. No correlation between the plate‐like oxygen precipitates related absorption at 1225 cm‐1 and dislocation‐related emission has been confirmed. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Infrared studies of oxygen-related defect formation in neutron-irradiated Cz-silicon after annealing at T=450–650 °C under hydrostatic pressure

The infrared absorption technique was used for the studies of oxygen aggregates and related defects in 5 MeV neutron-irradiated Czochralski-grown silicon after heat treatment (HT) at 450 and 650 °C under hydrostatic pressures (HP) of 1 and 1.1 GPa, respectively. The results obtained showed that the formation processes of classical thermal double donors (TDDs) are reduced in neutron-irradiated Si subjected to HP–HT treatment. This result can be explained in terms of higher formation rates of V–O defects, the so-called A-centres. The enhanced oxygen precipitation and shallow thermal donor formation are observed after HP–HT treatment at T=650 °C.