Cleanliness of Ti-bearing Al-killed ultra-low-carbon steel during different heating processes

During the production of Ti-bearing Al-killed ultra-low-carbon(ULC) steel, two different heating processes were used when the converter tapping temperature or the molten steel temperature in the Ruhrstahl–Heraeus(RH) process was low: heating by Al addition during the RH decarburization process and final deoxidation at the end of the RH decarburization process(process-Ⅰ), and increasing the oxygen content at the end of RH decarburization, heating and final deoxidation by one-time Al addition(process-Ⅱ). Temperature increases of 10°C by different processes were studied; the results showed that the two heating processes could achieve the same heating effect. The T.[O] content in the slab and the refining process was better controlled by process-Ⅰ than by process-Ⅱ. Statistical analysis of inclusions showed that the numbers of inclusions in the slab obtained by process-Ⅰ were substantially less than those in the slab obtained by process-Ⅱ. For process-Ⅰ, the Al_2O_3 inclusions produced by Al added to induce heating were substantially removed at the end of decarburization. The amounts of inclusions were substantially greater for process-Ⅱ than for process-Ⅰ at different refining stages because of the higher dissolved oxygen concentration in process-Ⅱ. Industrial test results showed that process-Ⅰ was more beneficial for improving the cleanliness of molten steel.

Relationship between Oxygen Chemical Potential and Steel Cleanliness

To investigate inclusion formation in each step during steel making process, several samples were taken in different steps of the production of steel at Mobarakeh Steel Co of Esfahan to measure the oxygen chemical potential of the molten steel in each stage. The chemical compositions of the inclusions in samples were investigated by scanning electron microscope. The chemical composition of the slag was analyzed. With the use of thermodnamic calculations and chemical analysis of the melt, at the working temperature, the relationship between dissolved oxygen and other elements were determined. Finally, it was found that there is a close relationship between inclusions formed in each step with the oxygen partial pressure.

Effect of slag composition on the cleanliness of 28MnCr5 gear steel in the refining processes

The equilibrium reaction between CaO-Al2O3-SiO2-MgO slag and 28MnCr5 molten steel was calculated to obtain the suitable slag composition which is effective for decreasing the oxygen content in molten steel. The dissolved oxygen content [O] in molten steel un- der different top slag conditions was calculated using a thermodynamic model and was measured using an electromotive force method in slag-steel equilibrium experiments at 1873 K. The relations among [O], the total oxygen content （T.O）, and the composition of the slag were investigated. The experimental results show that both [O] and T.O decrease with decreasing SiO2 content of the slag and exhibit different trends with the changes in the CaO/Al2O3 mass ratio of the slag. Increasing the CaO/Al2O3 mass ratio results in a decrease in [O] and an in- crease in T.O. To ensure that T.O ≤ 20 ppm and [O] ≤ 10 ppm, the SiO2 content should be controlled to 〈5wt%, and the CaO/AI203 mass ratio should be in the range from 1.2 to 1.6.

Best practices for making high integrity lightweight metal castings-molten metal composition and cleanliness control

To make high integrity lightweight metal castings,best practices are required in various stages of casting and heat treatment processes,including liquid metal composition and quality control,casting and gating/riser system design,and process optimization.This paper presents best practices for liquid metal processing and quality assurance of molten metal in both melting and mold filling.Best practices for other aspects of lightweight metal casting will be published separately.

Method for evaluation of the cleanliness grade of coal resources in the Huainan Coalfield,Anhui,China:a case study

Based on analysis of a large data set and supplementary sampling and analysis for hazardous trace elements in coal samples from the Huainan Coalfield,a generalized contrast-weighted scale index method was used to establish a model to evaluate the grade of coal cleanliness and its regional distribution in the main coal seam(No.13-1)The results showed that:(1)The contents of Cr,Mn and Ni in the coal seam are relatively high and the average values are greater than 20μg/g.The contents of Se and Hg are at a high level while most other trace elements are at normal levels.(2)The cleanliness grade of the coal seam is mainly grade III-IV,which corresponds to a relatively good-medium coal cleanliness grade.However,some parts of the seam are at grade V(relatively poor coal cleanliness).(3)Coal of relatively good cleanliness grade(grade III)is distributed mainly in the regions corresponding to the Zhuji-Dingji-Gubei coal mines and in the eastern periphery of the Panji coal mine.Coal of medium cleanliness(grade IV)is distributed mainly in the regions of the Panji-Xiejiaji and Kouzidong coalmines.Relatively poor grade coal(grade V)is distributed in the southwest regions of the coalfield and the contents of Cr,As and Hg in coal collected from the relatively poor coal cleanliness regions often exceed the regulatory standards for the maximum concentration limits.

Influence of group B streptococcus and vaginal cleanliness on the vaginal microbiome of pregnant women

BACKGROUND The vaginal microbiome plays a critical role in the health of pregnant women and their newborns.Group B Streptococcus(GBS)and vaginal cleanliness significantly affect the vaginal microecosystem and are closely associated with vaginal diseases.AIM To explore the effects of GBS status and vaginal cleanliness on vaginal microecosystems.METHODS We collected 160 vaginal swabs from pregnant women and divided them into the following four groups based on GBS status and vaginal cleanliness:GBS-positive+vaginal cleanliness I–II degree,GBS-negative+vaginal cleanliness I–II degree,GBS-positive+vaginal cleanliness III–IV degree,and GBS-negative+vaginal cleanliness III–IV degree.Samples were subjected to 16S rRNA gene amplicon sequencing.RESULTS Alpha diversity analysis showed that the Shannon index did not significantly differ between the four groups.We identified significant variation in taxa abundance between the GBS-positive and GBS-negative groups and between the vaginal cleanliness I–II degree and III–IV degree groups.Principal coordinate analysis and non-metric multidimensional scaling analysis further confirmed the microbial diversity of the four groups.Moreover,the linear discriminant analysis demonstrated that Lactobacillus jensenii and Actinobacteria were strongly associated with GBS-positive status,and Lactobacillus iners,Lactobacillaceae,Lactobacillus,Lactobacillales,Bacilli and Firmicutes were closely correlated with GBS-negative status.CONCLUSION GBS status and vaginal cleanliness significantly affect vaginal microbiome differences in pregnant women.Our findings provide instructional information for clinical antibiotic treatment in pregnant women with different GBS statuses and vaginal cleanliness degrees.

Methods of evaluating cleanliness of ventilation ducts

A testing system for evaluating cleanliness of ventilation ducts was constructed. Comparisons of four evaluation methods for quantifying the amount of dust on the inner surface of ventilation ducts are presented. The experimental results show that the wiping by solvent method is more efficient than that by the wiping method,especially used on low cleanliness duct surface. The gravimetric tape method is an efficient method of collecting dust samples on the duct surface with low amounts of dust,particularly used to check the cleanliness level after the cleaning work. The optical method can be set up rapidly and is useful for fieldwork measurements.

Effect of Tundish Lining on Steel Cleanliness

To clarify the effect of the tundish lining on the steel cleanliness,the MgO based and Al2 O3 based gunning materials（ GM） were used as the lining of the alumina crucibles,respectively,in which about 200 g of ultra-low carbon steel was charged at 1 823 K for 2 h in pure argon atmosphere. The chemical analysis was carried out to investigate the change of chemical composition of steel in contact with GM after high temperatures holding experiments. The steel cleanliness in terms of inclusion number density,inclusion size and inclusion size distribution was evaluated by SEM and EDS. It was found that the MgO GM provided more oxygen and showed a stronger oxidizing capacity due to its higher content of reducible oxides（ 10. 5 mass% SiO2＋ 2 mass%Fe2 O3）. The use of Al2 O3 GM resulted in an improved steel cleanliness and consequently Al2 O3 GM could be a promising refractory material in the tundish lining.

Advanced manufacturing technologies of large martensitic stainless steel castings with ultra low carbon and high cleanliness

The key manufacturing technologies associated with composition, microstructure, mechanical properties, casting quality and key process control for large martensitic stainless steel castings are involved in this paper. The achievements fully satisfeid the technical requirements of the large 700 MW stainless steel hydraulic turbine runner for the Three Gorges Hydropower Station, and become the major technical support for the design and manufacture of the largest 700 MW hydraulic turbine generator unit in the world developed through our own efforts. The characteristics of a new high yield to tensile strength (R p0.2/R m ) ratio and high obdurability martensitic stainless steel with ultra low carbon and high cleanliness are also described. Over the next ten years, the large martensitic stainless steel castings and advanced manufacturing technologies will see a huge demand in clean energy industry such as nuclear power, hydraulic power at home and abroad. Therefore, the new high yield o tensile strength (R p0.2/R m ) ratio and high obdurability martensitic stainless steel materials, the fast and flexible manufacturing technologies of large size castings, and new environment friendly sustainable process will face new challenges and opportunities.

Helicobacter pylori infection may result in poor gastric cleanliness in magnetically controlled capsule gastroscopy examination: A singlecenter retrospective study

Objective:Magnetically controlled capsule gastroscopy(MCCG)is an effective method for screening gastric diseases;however,its performance may be affected by gastric cleanliness.We aimed to explore the correlation between Helicobacter pylori infection and the degree of gastric cleanliness in the MCCG.Methods:This retrospective study enrolled 297 participants from October 2020 to April 2024 at Sir Run Run Shaw Hospital,Zhejiang University School of Medicine.Participant characteristics,MCCG examination results,and(13)C-urea breath test(C13-UBT)results were collected.The gastric cleanliness in MCCG examinations was assessed using a gastric cleanliness score.Binary logistic regression was used to analyze the relationships among participant characteristics,H.pylori infection,and gastric cleanliness.Chi-square tests and Fisher's exact tests were used to analyze the relationships among gastric lesions,H.pylori infection,and gastric cleanliness.Results:Among the participants,24.2%had H.pylori infection,and 17.5%had poor gastric cleanliness.Hypertension(odds ratio[OR]:2.63;95%confidence interval[CI]:1.36e5.09;p?0.004)was associated with a greater likelihood of H.pylori infection.H.pylori infection(OR:3.76;95%CI:1.99e7.09;p<0.001)was an independent risk factor for poor gastric cleanliness in the MCCG.A significant disparity was noted in the prevalence of focal erosions(p<0.001),gastric ulcers(p?0.001),and positive gastric lesions(p?0.027)between the 2 groups with and without H.pylori infection.The proportion of positive gastric lesions was not significantly different between the good gastric cleanliness group and the poor gastric cleanliness group(25.7%vs.21.2%;p?0.490).Conclusion:The findings of this study revealed that H.pylori infection was associated with hypertension.H.pylori infection may lead to poor gastric cleanliness.Institutions are advised to perform C13-UBT before MCCG,and participants should be informed of the risk of poor gastric cleanliness if the results are positive.The decision to perform H.pylori eradication before MCCG should take into account patient willingness and the benefit-to-risk ratio.

Effect of refining slag containing Ce_2O_3 on steel cleanliness

The effect of pre-melting refining slag containing different contents of Ce2O3 on the absorption and modification of Al2O3 inclusion in an Al-killed steel was investigated through the slag/steel reaction experiment at 1600 oC.It was found that the replacement of 10 wt.% Al2O3 with Ce2O3 for 50 wt.%CaO-33 wt.%Al2O3-7 wt.%MgO-10 wt.%SiO2 refining slag promoted the slag absorption ability of alumina inclusion,which made the total oxygen content determined by infrared absorption method decrease from 100 to 25 ppm in 15 min.The Mg-Al-Ce-O type inclusion was also detected in the as-solidified samples by scanning electron microscopy（SEM）.Thermodynamic analysis indicated that the Ce2O3.Al2O3 type inclusions would be formed with the cerium content in the range of 6.9 ppb to 3.6 ppm when the content of aluminum was 0.01 wt.%.

Challenges in determination of microscopic degree of cleanliness in ultra-clean gear steels

Shot-peened,case-hardened gears can fail in the tooth root due to crack initiation below the surface of the steel matrix.Here,the crack is initiated at a non-metallic inclusion in the center of a so-called fisheye.This failure type can lead to a reduced endurance fatigue limit of the gears.It is for this reason that,over the last decade,much effort has been invested by steel manufacturers to reduce the non-metallic inclusion content of gear steels so as to mitigate or even completely prevent such crack initiation.These ultra-clean gear steels were achieved by various measures in the steel production process.However,as a result,the remaining non-metallic inclusions are inhomogeneously distributed in the steel volume in terms of both size and location.However,due to the inhomogeneity of ultra-clean steels,the question arose if the values derived according to the standards are still representative of ultra-clean steel batches.The results show that the standards can still be applied,but more effort must be applied.To determine the degree of cleanliness,six microsections are currently evaluated according to steel test specification(SEP)1571,method K.It is shown that an examination of 24 microsections starting from size class 0 seems beneficial to get more reliable and comparable results of the degree of cleanliness of these ultra-clean gear steels.In addition,it is shown that a high degree of cleanliness has been achieved for all steel batches investigated with the measures taken in the steel production process.

Optimizing the cleanliness in multi-segment disk amplifiers based on vector flow schemes

The objective of maintaining the cleanliness of the multi-segment disk amplifier in Shenguang-II(SG-II) is to reduce laser-induced damage for optics. The flow field of clean gas, which is used for the transportation of contaminant particles,is a key factor affecting the cleanliness level in the multi-segment disk amplifier. We developed a gas–solid coupling and three-dimensional flow numerical simulation model. The three-dimensional and two-phase flow model is verified by the flow-field smog experiment and the particle concentration measurement experiment with the 130-disk amplifier in SG-II. By optimizing the boundary conditions with the same flow rate, the multi-inlet vector flow scheme can not only effectively reduce the purging time, but also prevent the reverse diffusion of contaminant particles in the multi-segment disk amplifier and the deposition of contaminant particles on the surface of the Nd:glass.

Effect of axial static magnetic field on cleanliness and microstructure in magnetically controlled electroslag remelted bearing steel

The effect of the axial static magnetic field(ASMF)on cleanliness and microstructure in magnetically controlled electroslag remelted GCr15 bearing steel ingots was investigated experimentally.The results show that a magnetically controlled spin-vibration induced by the interaction of the ASMFs and the remelting current exists at the consumable electrode tip,resulting in thinner liquid melt film and smaller droplets.With the increase in magnetic flux density,the optimization effect of ASMFs on electroslag remelting process increases and reaches the peak with a 40 mT ASMF,then decreases.The cleanliness of the ingots was improved,and the count of inclusions larger than 5μm was reduced.The microstructure of the ingots processed with a 40 mT ASMF was significantly refined.The depth of the metallic molten pool was reduced from 45.2 to 17.5 mm with the application of 40 mT ASMF.The tensile strength,impact toughness,and Rockwell hardness of the ingots obtained under the 40 mT ASMF were significantly improved.The mechanisms of the spin-vibration occurring at the electrode tip end were interpreted in detail to elucidate the effect of ASMFs.

A novel cleanliness control method for disk amplifiers

As the key part for energy amplification of high-power laser systems,disk amplifiers must work in an extremely clean environment.Different from the traditional cleanliness control scheme of active intake and passive exhaust(AIPE),a new method of active exhaust and passive intake(AEPI)is proposed in this paper.Combined with computational fluid dynamics(CFD)technology,through the optimization design of the sizes,shapes,and locations of different outlets and inlets,the turbulence that is unfavorable to cleanliness control is effectively avoided in the disk amplifier cavity during the process of AEPI.Finally,the cleanliness control of the cavity of the disk amplifier can be realized just by once exhaust.Meanwhile,the micro negative pressure environment in the amplifier cavity produced during the exhaust process reduces the requirement for sealing.This method is simple,time saving,gas saving,efficient,and safe.It is also suitable for the cleanliness control of similar amplifiers.

Influence of metallurgical processing parameters on defects in cold-rolled steel sheet caused by inclusions

The cleanliness and defects for cold-rolled steel sheet caused by inclusions are greatly influenced by parameters in the metallurgical processing. Good control of parameters during the processing can lead to a better product. In this paper, data mining was used to explore the influence of parameters on defects in steel sheets. A decision tree model was established and it was found that the oxygen content before deoxidation, the end-point temperature of the converter, and the temperature before deoxidation had a great impact on the defects in the cold-rolled sheet that were caused by inclusions. This finding was confirmed by experiments with infrared absorption, scanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS), and automatic inclusion analysis methods. After optimization according to results from the model and experiments, the defect rate caused by the inclusions was reduced from 0.92% to 0.38%.

Foliar Particulate Matter Distribution in Urban Road System of Beijing, China

Particulate matter(PM), one of the most important pollutants of traffic emission, threatens the health of urban ecosystems and citizens. Roadside trees play an important role in trapping PM, and the foliar PM load is a useful indicator for air PM pollution in road systems. To detect the relationships of foliar PM load with road structures, urbanization, and meteorology in road systems, we studied a widely-planted tree Sophora japonica L. in 100 roads and 10 yards of Beijing, China, and found that the foliar PM loads increased with the distances from the urban centre(DUC) linearly, while decreased with the road density. All-subsets regression analysis indicated that DUC, average monthly relative humidity, average monthly wind speed, and mean annual wind speed were the most important factors in predicting foliar PM load, rather than general situation of buildings and road cleanliness. The monthly relative humidity and monthly wind speed had a negative correlation to foliar PM, while the annual relative humidity and annual wind speed had a positive correlation to foliar PM. Suburban areas and these effective factors should be highlighted in PM control in Beijing.

BRIEF ARTICLE New reduced volume preparation regimen in colon capsule endoscopy

AIM:To evaluate the effectiveness of our proposed bowel preparation method for colon capsule endoscopy.METHODS:A pilot,multicenter,randomized controlled trial compared our proposed "reduced volume method"(group A) with the "conventional volume method"(group B) preparation regimens.Group A did not drink polyethylene glycol electrolyte lavage solution(PEGELS) the day before the capsule procedure,while group B drank 2 L.During the procedure day,groups A and B drank 2 L and 1 L of PEG-ELS,respectively,and swallowed the colon capsule(PillCam COLON capsule).Two hours later the first booster of 100 g magnesium citrate mixed with 900 mL water was administered to both groups,and the second booster was administered six hours post capsule ingestion as long as the capsule had not been excreted by that time.Capsule videos were reviewed for grading of cleansing level,RESULTS:Sixty-four subjects were enrolled,with results from 60 analyzed.Groups A and B included 31 and 29 subjects,respectively.Twenty-nine(94%) subjects in group A and 25(86%) subjects in group B had adequate bowel preparation(ns).Twenty-two(71%) of the 31 subjects in group A excreted the capsule within its battery life compared to 16(55%) of the 29 subjects in group B(ns).Of the remaining 22 subjects whose capsules were not excreted within the battery life,all of the capsules reached the left side colon before they stopped functioning.A single adverse event was reported in one subject who had mild symptoms of nausea and vomiting one hour after starting to drink PEG-ELS,due to ingesting the PEG-ELS faster than recommended.CONCLUSION:Our proposed reduced volume bowel preparation method for colon capsule without PEG-ELS during the days before the procedure was as effective as the conventional volume method.

Emerging melt quality control solution technologies for aluminium melt

The newly developed ＂MTS 1500＂ Melt Treatment System is performing the specifically required melt treatment operations like degassing, cleaning, modification and/or grain refinement by an automated process in one step and at the same location. This linked process is saving time, energy and metal losses allowing - by automated dosage of the melt treatment agents - the production of a consistent melt quality batch after batch. By linking the MTS Metal Treatment System with sensors operating on-line in the melt, i.e., with a hydrogen sensor ＂Alspek H＂, a fully automated control of parts of the process chain like degassing is possible. This technology does guarantee a pre-specified and documented melt quality in each melt treatment batch. Furthermore, to ensure that castings are consistent and predictable there is a growing realization that cdtical parameters such as metal cleanliness must be measured prior to casting. There exists accepted methods for measuring the cleanliness of an aluminum melt but these can be both slow and costly. A simple, rapid and meaningful method of measuring and bench marking the cleanliness of an aluminum melt has been developed to offer the foundry a practical method of measuring melt cleanliness. This paper shows the structure and performance of the integrated MTS melt treatment process and documents achieved melt quality standards after degassing, cleaning, modification and grain refinement operations under real foundry conditions. It also provides an insight on a melt cleanliness measuring device ＂Alspek MQ＂ to provide foundry men better tools in meeting the increasing quality and tighter specification demand from the industry.

PillCamColon2 after incomplete colonoscopy-A prospective multicenter study

AIM To evaluate the ability of PillCamColon2 to visualize colonic segments missed by incomplete optical colonoscopy(OC) and to assess the diagnostic yield.METHODS This prospective multicentre study included 81 patients from nine centres who underwent second-generation colon capsule endoscopy(CCE) following incomplete OC performed by an experienced gastroenterologist(> 1000 colonoscopies). Patients with stenosis were excluded. According to patient preferences, CCE was performed the following day(protocol A) after staying on clear liquids and 0.75 L Moviprep in the morning or within 30 d after new split-dose Moviprep(protocol B). Boosts consisted of 0.75 L and 0.25 L Moviprep, and phospho-soda was given as a rescue if the capsule was not excreted after seven hours.RESULTS Seventy-four patients were analysed(51% of them in group A; 49% in group B). Bowel cleansing was adequate in 67% of cases, and CCE could visualize colonic segments missed by incomplete colonoscopy in 90% of patients under protocol A and 97% of patients under protocol B(P = 0.35, n.s.). Significant polyps including adenocarcinoma were detected in 24% of cases. Detection rates for all polyps and significant polyps per patient were similar in both protocols. Polyps were found predominantly in the right colon(86%) in segments that were not reached by OC. Extracolonic findings-such as reflux esophagitis, suspected Barrett esophagus, upper GI-bleeding, gastric polyps, gastric erosions and angiectasia-were detected in eight patients. Pill Cam Colon2 capsule was retained in the ileum of one patient(1.4%) without symptoms and removed during an uneventful resection for unknown Crohn's disease that was diagnosed as the cause of anemia, which was the indication for colonoscopy. CCE was well tolerated. One patient suffered from selflimiting vomiting after consuming the phospho-soda.CONCLUSION Second-generation CCE using a low-volume preparation is useful after incomplete OC, and it allows for the detection of additional relevant findings, but cleansing efficiency could be improved.