Secondary Refining Research Articles

Evolution of Non-metallic Inclusions in Si-Ca-Ba-Killed Heavy Rail Steel During Secondary Refining Process

Evolution of Non-metallic Inclusions in Si-Ca-Ba-Killed Heavy Rail Steel During Secondary Refining Process

The Inclusion Characteristics and Mechanical Properties of M2 High-Speed Steel Treated with a Vacuum Carbon Deoxidation Process

The oxygen content of M2 high-speed steel has not been intentionally controlled in industrial production through secondary refinement in vacuum furnaces. However, a lower oxygen content has a significant effect on the cleanliness, toughness, and addition of rare-earth elements to M2 high-speed steel. The changes in total oxygen content controlled by vacuum carbon deoxidation (VCD) treatment and inclusion evolution were investigated in M2 high-speed steel to understand the effects of carbon on dissolved oxygen and oxides in the carbon–oxygen (C-O) reaction process. Furthermore, the microstructure and properties of M2 high-speed steel caused by vacuum insulation and the role of reducing oxygen content in rare-earth alloying were briefly demonstrated. The results showed that the [O%] decreased from 30 ppm to 3 ppm in a vacuum at holding times above 25 min through the C-O reaction, leading to an inclusion reduction of approximately 70%. In the case of [O%] = 3 ppm in M2 high-speed steel, the addition of rare-earth elements has a greater effect on the inclusion characteristics. Lowering the oxygen content of M2 high-speed steel improves cleanliness and plays a significant role in rare-earth alloying.

Super‐evolutionary mechanism and Nelder‐Mead simplex enhanced salp swarm algorithm for photovoltaic model parameter estimation

AbstractIn the pursuit of enhancing the efficiency of solar cells, accurate estimation of unspecified parameters in the solar photovoltaic (PV) cell model is imperative. An advanced salp swarm algorithm called the Super‐Evolutionary Nelder‐Mead Salp Swarm Algorithm (SENMSSA) is proposed to achieve this objective. The proposed SENMSSA addresses the limitations of SSA by incorporating a super‐evolutionary mechanism based on a Gaussian‐Cauchy mutation and a vertical and horizontal crossover mechanism. This mechanism enhances both the global optimization capabilities and the local search performance and convergence speed of the algorithm. It enables a secondary refinement of the global optimum, unlocking untapped potential in the solution space near the global optimum and elevating the algorithm's precision and exploitation capabilities to higher levels. The Nelder‐Mead simplex method is further introduced to enhance local search capabilities and convergence accuracy. The Nelder‐Mead simplex method is a versatile optimization algorithm that improves local search by iteratively adjusting a geometric shape (simplex) of points. It operates without needing derivatives, making it suitable for non‐smooth or complex objective functions. To assess the efficacy of SENMSSA, a comparative analysis is conducted against other available algorithms, namely SSA, IWOA, SCADE, LWOA, CBA, and RCBA, using the CEC2014 benchmark function set. Subsequently, the algorithm was employed to determine the unknown PV parameters under fixed conditions for three different diode models. Additionally, SENMSSA is utilized to estimate PV parameters for three commercially available PV models (ST40, SM55, KC200GT) under varying conditions. The experimental results indicate that the SENMSSA proposed in this study displays a remarkably competitive performance in all test cases compared to other algorithms. As such, we consider that the SENMSSA algorithm constitutes a reliable and efficient solution for the challenge of PV parameter estimation.

Reoxidation Phenomena of Liquid Steel in Secondary Refining and Continuous Casting Processes: A Review

This review article reports the critical issue of reoxidation in clean steel production during secondary refining and continuous casting processes. Reoxidation presents substantial challenges to process stability and final product quality. Various sources of reoxidation, including exposure to oxidizing gases, reducible oxides in slag and refractories, and the presence of ferroalloys are explored. Fundamental reactions and their consequences, such as changes in steel composition, inclusion composition/morphology, and the formation of reaction products at the interface between liquid steel and refractory materials, are reviewed. High oxygen partial pressure on the refractory side is identified as a significant factor, particularly in tundish and continuous casting processes. To address reoxidation effectively, the review discusses modeling approaches like computational fluid dynamics and thermodynamic/kinetic modeling. In the industrial context, reoxidation in the tundish is mainly attributed to open‐eye formation in the tundish flux and reducible oxides like SiO2 in an insulating cover powder, for example, rice hust ash. Maintaining precise tundish flux control is crucial for steel cleanliness. In conclusion, this review highlights the multifaceted nature of reoxidation challenges in clean steel production. A comprehensive understanding of reoxidation mechanisms and the implementation of effective strategies are essential for achieving cleaner steel production.

From Esthetic Medicine to Optimizing Reconstructive Outcome: A Feasibility Trial on Secondary Refinement of Fasciocutaneous Anterolateral Thigh Flaps with Cryolipolysis.

Free adipocutaneous anterolateral thigh (ALT) flaps have evolved as workhorse flaps to reconstruct complex, multicompound defects. While coverage is safely achieved, flaps may remain bulky. As a standard of care, flaps are refined with liposuction, partial excision, or combination of both. Cryolipolysis is widely used for fat reduction in esthetic medicine. This pilot comparative study analyses whether cryolipolysis may serve as a safe alternative method to effectively reduce volume in fasciocutaneous flaps. Moreover, patients' satisfaction with the procedure is evaluated. In this single-center, retrospective, interventional comparative cohort study, 10 patients with free subfascial ALT flaps for distal extremity reconstruction underwent cryolipolysis (60 minutes, -9°C). Circumference of the extremities and subcutaneous fat thickness were determined before (T1) and 12 weeks (T2) after cryolipolysis. Patient satisfaction was evaluated with a questionnaire of Likert's scale questions. Duration of hospital stay, intervention time, costs, and possible complications were analyzed and compared with surgical flap contouring (n = 12). All patients undergoing cryolipolysis were male, with a median age of 52 years without arterial disease-like state or deep vein thrombosis (DVT). At T2, a significant reduction of circumference of 1.8 ± 0.9 cm (p < 0.001) and subcutaneous fat layer of 7.7 ± 3.0 mm (p < 0.0001) was recorded. Overall, 90% of the patients were satisfied with the result. Cryolipolysis was well tolerated. One patient developed a second-degree frostbite which healed without further intervention. Cryolipolysis proofed to be as safe as surgical flap contouring. Hospital stay was significantly shorter (p < 0.01) and personal resources were spared when flap contouring was performed with cryolipolysis. This is a novel application of evolving body-contouring cryolipolysis from esthetic medicine into optimizing outcomes in reconstructive surgery. Cryolipolysis has been shown to be relatively safe and effective to reduce ALT's volume with high patients' satisfaction. This successful pilot study encourages further investigation with a prospective randomized control trial.

The "Sombrero-Shape" Super-Thin Pedicled ALT Flap for Complete Scrotal Reconstruction Following Fournier's Gangrene.

When the scrotal sac is entirely debrided following a Fournier gangrene, testes exposure poses unique challenges for the reconstructive surgeon. Despite the anterolateral thigh (ALT) flap is considered a workhorse in such context, aesthetic results are often suboptimal because of the lack of natural ptosis and patchwork appearance. We describe the use of a super-thin pedicled ALT flap for total scrotal reconstruction, modified according to a peculiar flap design and inset technique. A 42-year-old man was referred to our department for delayed total scrotal reconstruction 8 months after a Fournier gangrene extensive debridement. A super-thin pedicled ALT flap from the right thigh was designed: in the central portion of the ALT, a lateral skin paddle extension was marked to guarantee adequate posterior anchorage during insetting and ptosis of the scrotal sac. This particular flap arrangement has inspired the name “sombrero” as the shape is akin to the famous hat. No secondary refinements were needed, and the patient showed satisfying aesthetic and functional results at 12 months' follow-up. The ALT flap design “sombrero” modification proposed in this article can improve scrotum cosmesis and patient satisfaction in a single-stage single-flap procedure.

Reducing the Cost of Steel Desulfurization during Secondary Refining in a Ladle-Furnace Unit

Reducing the Cost of Steel Desulfurization during Secondary Refining in a Ladle-Furnace Unit

Effects of temperature on melt electrospinning with auxiliary heating: experiment and simulation study

In this study, the effect of the heating temperature of the spinneret on the melt electrospinning process under the condition of application of auxiliary heating was investigated, in a systematical and comprehensive way. The temperature distribution of the melt jet during the melt electrospinning process was simulated by finite element software in order to provide a good deal of insight into the experimental results. In addition, high-speed photography was adopted to capture images of jet formation and jet motion during the melt electrospinning process. The experimental results indicated that the cooling rate of the polypropylene jet decreases obviously under the condition of auxiliary heating; in addition, the higher spinneret temperature leads to greater drafting force, a drawing fiber drafting rate, and greater jet whipping motion, which is conducive to secondary drawing and refinement of the jet.

Study on the Composition and Interface of Waste Silicon Slag After Secondary Refining

Silicon slag is a secondary refining by-product from industrial silicon. The content of industrial silicon in silicon slag is about 20 %, which has extremely high economic value. To better achieve the recovery and reuse of industrial silicon slag, the morphology of industrial silicon slag, the occurrence state of elements and especially the interfacial structure between silicon and slag were deeply studied. The results showed that the purity of silicon particles in silicon slag is high up to 99 %. The interface between silicon and slag is clear and there is no obvious two-phase transition zone, which is beneficial to realize the recycling of silicon by breaking the silicon slag. The dissociated silicon slag was screened out for melting and refining. The results showed that the silicon phase was separated from the slag phase. In this paper, the physical and chemical properties of industrial silicon slag were studied, which provides a theoretical basis for the efficient separation and recovery of silicon in the slag.

Influence of Secondary Refining on the Non-Metallic Inclusions Rating during 26KhMFBA Steel Melting

Influence of Secondary Refining on the Non-Metallic Inclusions Rating during 26KhMFBA Steel Melting

The transverse musculocutaneous gracilis flap for autologous breast reconstruction: focus on donor site morbidity

PurposeThe transverse musculocutaneous gracilis (TMG) flap is as a valuable alternative in autologous breast reconstruction. The purpose of this study was to evaluate the donor site morbidity and secondary refinement procedures after TMG flap breast reconstruction.MethodsA retrospective study was conducted, including all patients who received TMG flap breast reconstructions, from January 2012 to August 2019. Primary outcomes were surgical site complications of the donor site and secondary refinement procedures carried out for aesthetic or reconstructive purposes for the medial thigh. Secondary outcomes of interest were lipofilling procedures for optimization of the reconstructed breasts.ResultsNinety-nine patients received 159 TMG flaps for breast reconstruction. Patients’ mean BMI was 23.5 (15.6–32.5) kg/m2. Bilateral breast reconstructions were performed in 60.6%. The mean flap volume was 330 (231–440) g. Surgical site complications occurred in 14.5% of the TMG donor sites and wound dehiscence was the most common complication (9.4%). Lymphedema occurred in 1.8% of the donor thighs. Aesthetic refinement procedures were performed in 25.2% on the donor thigh or contralateral thigh. Secondary lipofilling was performed in 54.1% of the reconstructed breasts and fat was harvested in only 11.9% from the legs.ConclusionThe TMG flap breast reconstruction combines low donor site morbidity with adequate volume for appealing breast results, particularly in slim-to-normal weight patients. However, patients should be informed about the likelihood of secondary refinement procedures on the donor site and the need of lipofilling to optimize the breast shape and volume.

Evaluation of secondary refinement procedures following free microvascular tissue reconstruction of the upper extremity

The primary cosmetic and functional outcome following successful upper limb salvage using free tissue transfer can often be unfavourable, which may motivate patients to undergo secondary procedures. In this study, we sought to identify predictors for secondary procedures and to analyse the type and number of these procedures. Patients who underwent free tissue transfer to the upper extremity between 2010 and 2017 were included in a retrospective cohort study: patients with secondary procedures to optimise the functional and aesthetic flap design (S cohort) vs. control cohort (C cohort). A multivariate regression analysis was used to identify predictors for secondary procedures. One hundred and twenty-eight patients were included in the study (S cohort 36, C cohort 92). All in all, 56 secondary refinement procedures were performed in a mean of eight months after the initial free flap reconstruction. Most of the defects in the S cohort were localised at the hand (53 %), and upper limb salvage was mostly accomplished by fasciocutaneous and adipocutaneous free flaps (S cohort 89 %). The most frequently performed secondary refinement procedures were direct partial flap excision (61 %), followed by liposuction (16 %) and the combination of both (17 %). Furthermore, 64 % of the secondary refinement procedures from the S cohort were combined with further surgical interventions to improve hand function, e. g. tenolysis and arthrolysis. Patients with defects of the hand received secondary procedures 2.4 times more frequently (p = 0.05). Also, patients with a good general health condition (ASA 1 and 2) were six times more likely to undergo a secondary procedure (p = 0.03). Secondary procedures are safe and frequently requested by patients following successful free flap upper limb salvage. In particular, this applies to patients who are in a good health condition and with free flaps to the hand. Therefore, we recommend the implementation of secondary refinement procedures in the reconstructive plan to increase patient compliance and satisfaction.

The Post-ICU presentation screen (PICUPS) and rehabilitation prescription (RP) for intensive care survivors part II: Clinical engagement and future directions for the national Post-Intensive care Rehabilitation Collaborative.

Many Intensive Care Unit (ICU) survivors suffer from a multi- system disability, termed the post-intensive care syndrome. There is no current national coordination of either rehabilitation pathways or related data collection for them. In the last year, the need for tools to systematically identify the multidisciplinary rehabilitation needs of severely affected COVID-19 survivors has become clear. Such tools offer the opportunity to improve rehabilitation for all critical illness survivors through provision of a personalised Rehabilitation Prescription (RP). The initial development and secondary refinement of such an assessment and data tools is described in the linked paper. We report here the clinical and workforce data that was generated as a result. Prospective service evaluation of 26 acute hospitals in England using the Post-ICU Presentation Screen (PICUPS) tool and the RP. The PICUPS tool comprised items in domains of a) Medical and essential care, b) Breathing and nutrition; c) Physical movement and d) Communication, cognition and behaviour. No difference was seen in total PICUPS scores between patients with or without COVID-19 (77 (IQR 60-92) vs. 84 (IQR 68-97); Mann-Whitney z = -1.46, p = 0.144. A network analysis demonstrated that requirements for physiotherapy, occupational therapy, speech and language therapy, dietetics and clinical psychology were closely related and unaffected by COVID-19 infection status. A greater proportion of COVID-19 patients were referred for inpatient rehabilitation (13% vs. 7%) and community-based rehabilitation (36% vs.15%). The RP informed by the PICUPS tool generally specified a greater need for multi-professional input when compared to rehabilitation plans instituted. The PICUPS tool is feasible to implement as a screening mechanism for post-intensive care syndrome. No differences are seen in the rehabilitation needs of patients with and without COVID-19 infection. The RP could be the vehicle that drives the professional interventions across the transitions from acute to community care. No single discipline dominates the rehabilitation requirements of these patients, reinforcing the need for a personalised RP for critical illness survivors.

Safety of a Modified Lipoabdominoplasty Technique for Donor-Site Closure in Abdominal-Based Free Flap Breast Reconstruction

The aesthetic and functional outcomes of the donor site following abdominal-based free flap breast reconstruction have been suboptimal. The objective of this study is to evaluate a modified liposuction-assisted abdominoplasty technique combined with rectus plication (LPARSP) adopted from cosmetic abdominoplasty practice. All abdominal-based free flap breast reconstructions from 01/2017 to 03/2019 were reviewed. Patients with central fullness and sufficient tissue surplus on the abdomen, thighs and flanks who received LPARSP and rectus plication were identified (LPARSP group) and matched for age and body mass index with patients who underwent conventional abdominoplasty (CA group). Abdominal skin sensation, objective functional and aesthetic measures of the abdomen, as well as patient-reported outcomes (Breast-Q), were analyzed. A total of 28 patients were included. Groups were similar in demographics. The mean amount of lipoaspirate in the LPARSP group was 1054±613.5ml. The postoperative course was similar in both groups. The LPARSP technique resulted in a lower positioned horizontal scar (p = 0.03). The aesthetic outcome was superior in the LPARSP group (p < 0.0001). Furthermore, the LPARSP group presented with a decreased bulging rate (p = 0.05), and secondary refinement procedures were less frequently demanded (p = 0.02). In addition, the abdominal wall sensation of the flanks was improved in the LPARSP group (p = 0.05), whereby patient-reported outcome measures did not differ between groups. Lipoabdominoplasty with rectus plication represents a safe approach for donor-site closure in selected patients undergoing abdominal-based free flap breast reconstruction. Superior functional and aesthetic results paired with improved abdominal wall sensation are achieved compared to CA. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Physical Simulation of a Nonconsumable Lance for Secondary Refining Operations

In this research, the proposal to use a nonconsumable lance or heat pipe to decrease the mixing times in a secondary refining ladle is evaluated. The main idea is to minimize the stirring times to get the complete mixing of liquid steel, mainly due to the fact that a consumable lance once its melted changes the operation conditions. Use of a nonconsumable lance is well known because of its excellent self-protective characteristics; in general, this kind of nonconsumable lance is used in almost any gas injection operation process. Hence, a set of experiments in a physical model demonstrated the viability and competitiveness of the nonconsumable lance in a secondary refining ladle. The results obtained in the physical modeling revealed that the vibration signals, acquired by the accelerometer, are proportional to the amount of agitation energy induced by the injected gas (kinetic and potential energy). Regarding the increment in the vibrations, the inclination angle of the lance showed that the mixing times have a significant effect on the mixing time of the liquid.

Effect of Ultra-sonicated Y2BaCuO5 on Top-Seeded Melt Growth YBa2Cu3Oy Bulk Superconductor

In this work, we tried to improve the superconducting performance of bulk YBa2Cu3Oy (Y123) superconductors via Y2Ba1Cu1O5 (Y211) secondary phase refinement. A novel method of ultra-sonication was used to refine the Y211 secondary phase particles. The Y211 powder was treated by ultra-sonication for 0 to 80 min with steps of 20 min, keeping the power (300 W) and frequency (20 kHz) constant. For synthesis of the YBCO bulk, we employed top-seeded melt growth (TSMG) with Pt addition. Magnetization measurements showed a superconducting transition temperature at around 91 K, irrespective of ultra-sonication parameters. Interestingly, critical current density and trapped field were found to be proportional to the ultra-sonication duration. YBCO bulk sample (20 mm diameter, 7 mm in thickness) fabricated for 80 min ultra-sonicated Y211 showed a maximum trapped field of 0.42 T at 77 K, 0.3 mm above the top surface. The improved trapped field values are explained on the basis of improvements in the microstructure.

Formation and Evolution of Non-metallic Inclusions in Ti-Bearing Al-Killed Steel During Secondary Refining Process

Industrial and laboratory experiments were carried out to investigate the formation and evolution of the inclusions in Ti-bearing Al-killed steel, and thermodynamic calculations were also conducted to check the stability of inclusions in steel. It is found that the addition of Ti influences the inclusions evidently. Before Ti addition, the inclusions transform along the route of “Al2O3 → MgO·Al2O3 spinel → CaO-Al2O3(-MgO) system” with the generation of dissolved Mg and Ca in liquid steel. When there is no sufficient Ca in liquid steel, the addition of Ti during refining process would lead to the transformation of MgO·Al2O3 spinel inclusions into MgO-Al2O3-TiOx inclusions. When a trace of dissolved Ca is formed, CaO-Al2O3-TiOx system inclusions can be generated from MgO-Al2O3-TiOx inclusions or CaO-Al2O3 inclusions. Higher calcium content originated from calcium treatment would result in the formation of CaO·TiO2 inclusions, and then weaken the castability of Ti-bearing Al-killed steel grades. Calcium treatment could also increase the frequency of macro-inclusions in steel, and evidently decline the quality of the steel. Cancellation of calcium treatment is suggested to improve the cleanliness of Ti-bearing Al-killed steel grades.

Physical Simulation Behavior of the Slag in Gas Injection with Non-consumable Lance and Porous Plug for Secondary Refining Operations

In secondary refining operations, injection of inert gases into the metal bath is required to generate stirring in order to produce cleaner steels with low sulfur, ultra-low contents of nitrogen and hydrogen gases as well as improving both temperature and composition homogenization of the steel and control the inclusions and floating of them. To demonstrate the viability and competitiveness of the non-consumable lance versus porous plugs, a series of experiments in a model of secondary refining ladle were carried out in previous research (Liu et al. in ISIJ Int 57:1971, 2017). Simulation of gas injection was carried out to test the two methods: porous plug and non-consumable lance. It was found that the porous plug injection involves shorter mixing times (10–12 s) when it is positioned in an intermediate point between the center and edge of the ladle and with the increase in the airflow injected, as compared to the lance. However, one problem with this technique in the actual plant is the metal oxidation because the liquid metal is exposed to air as a result of excessive agitation. In this work, gas injection through porous plug and non-consumable lance into secondary refining ladle was simulated by the addition of oils of different densities, to simulate the behavior of the slag of different viscosities. The results show that the non-consumable lance exhibits less water surface area exposed compared with the porous plug. This means less metal is exposed to the environment and less oxidation of it, under the same agitation conditions.

Numerical Simulation of the Three-Phase Flow of a Bubble Interacting with the Steel–Slag Interface During the Secondary Refining Process

Gas stirring is an effective method for the secondary refining process of steel. The microphenomena among the phases of an argon bubble floating in steel and motion across the steel–slag interface were simulated and discussed with a sharp interface tracking method. A water-model experiment was set to validate the numerical model, and the experimental results showed agreement with the numerical model. A critical size for bubbles to pass the interface was found using the model.

Analysis of Secondary Refining Slag Parameters with Focus on Inclusion Cleanliness

Secondary refining slag samples with different chemical compositions (45-54 % CaO, 7-13 % Al2O3, 20-29 % SiO2, 9-16 % MgO, 0-5 % CaF2) were investigated to verify the influence of their effective viscosity on inclusion cleanliness of DIN 38MnS6 in a steelmaking plant. The steel samples were collected during the production process for analysis of inclusions. Using the commercial software FactSage 6.4, thermodynamic calculations were performed to determine the effective viscosity, solid fraction, liquid fraction and MgO saturation point of these slags at 1560oC. The results showed that all the slags were saturated in MgO, revealing a better protection of the ladle refractory. The addition of 2 to 5 % of CaF2 reduced the effective viscosity values for the analyzed slags from 0.45 Pa∙s to 0.10 Pa∙s , in comparison to the slags without the addition of CaF2, with an effective viscosity of 0.40 Pa∙s, 0.27 Pa∙s and 0.22 Pa∙s, decreasing the level of non-metallic inclusions for some of the analysed heats. However, it was detected during the manufacturing process that high slag fluidity and re-oxidation events continue to be a challenge associated with reducing the level of non-metallic inclusions.