The mechanism of penetration increase in A-TIG welding

The mechanism of the increasing of A-TIG welding penetration is studied by using the activating flux we developed for stainless steel. The effect of flux on the flow and temperature fields of weld pool is simulated by the PHOENICS software. It shows that without flux, the fluid flow will be outward along the surface of the weld pool and then down, resulting in a flatter weld pool shape. With the flux, the oxygen, which changes the temperature dependence of surface tension grads from a negative value to a positive value, can cause significant changes on the weld penetration. Fluid flow will be inward along the surface of the weld pool toward the center and then down. This fluid flow pattern efficiently transfers heat to the weld root and produces a relatively deep and narrow weld. This change is the main cause of penetration increase. Moreover, arc construction can cause the weld width to become narrower and the penetration to become deeper, but this is not the main cause of penetration increase. The effects of flux on fluid flow of the weld pool surface and arc profiles were observed in conventional TIG welding and in A-TIG welding by using high-speed video camera. The fluid flow behavior was visualized in real-time scale by micro focused X-ray transmission video observation system. The result indicated that stronger inward fluid flow patterns leading to weld beads with narrower width and deeper penetration could be apparently identified in the case of A-TIG welding. The flux could change the direction of fluid flow in welding pool. It has a good agreement with the simulation results.     

Effects of Some Light Alloying Elements on the Oxidation Behavior of Fe and Ni-Cr Based Alloys During Air Plasma Spraying

The oxidation behavior of iron binary powders with addition of Si (1, 4 wt.%) and B (1, 3 wt.%) and that of a Ni-Cr based alloy powder with Si (4.3 wt.%), B (3.0 wt.%), and C (0.8 wt.%) additions during atmosphere plasma spray (APS) have been investigated. Analysis of the chemical composition and phases of oxides in the captured in-flight particles and deposited coatings was carried out. The results show that the addition of Si and B to iron effectively reduced the oxygen contents in the coatings, especially during the in-flight period at higher particles temperature. Ni-Cr based alloy powder with Si, B, and C additions reduced the oxidation of the base alloys significantly. Preferential oxidation and subsequent vaporization of Si, B, and C from the surface of the sprayed particles are believed to play a major role in controlling oxidation in the APS process.     

高炉操作对炉缸侵蚀的影响

 沙钢宏发炼铁厂1号高炉因炉缸侵蚀于2011年1月进行大修。炉缸内第6、7层碳砖侵蚀最严重,呈异常三角形侵蚀。通过对炉缸碳砖的分析和操作条件的模拟,发现高炉锌负荷过高和铁水环流是加剧炉缸侵蚀的主要原因。宏发高炉的锌负荷偏高,使ZnO在炉缸第6、7层碳砖中严重富集,导致碳砖导热系数下降,热膨胀系数增加,加剧碳砖的熔蚀和热应力引起的侵蚀。另外,由于原料质量和操作原因,使得宏发高炉的铁口长度较短、无焦区偏小和死料柱的透气透液性有时较差,加剧了铁水环流对炉缸的侵蚀。可以通过控制入炉锌负荷,延长铁口长度、控制死料柱的尺寸、提高焦炭质量和控制合适的喷煤比来改善炉缸的侵蚀。     

Porcine hemoglobin promotes lipid excretion to feces more strongly than globin protein in rats

In an effort to clarify whether the lipid-lowering effect of hemoglobin is due to globin protein or heme, this study investigated the effects of dietary porcine hemoglobin (PH) and porcine globin (PG) on lipids contents of serum, liver, and feces in rats. Five-week-old male Wistar rats were divided into 3 dietary groups of 7 rats each, with one group receiving a control diet and the other groups receiving diets containing 1.25% (w/w) PH or 1.18% (w/w) PG for 4 weeks. The PH diet decreased triacylglycerol content in serum and cholesterol in serum and liver, whereas the PG diet reduced triacylglycerol content in serum and cholesterol in liver. Fecal lipid excretion in the PH group was significantly higher than in the PG group. Therefore, PH affected lipid excretion to feces due to globin protein as well as heme.     

沙钢2500m~3高炉炉缸侧壁三角形侵蚀的原因分析

沙钢宏发1#高炉(2 500 m3)在2011年年初大修,发现炉缸侧壁在竖直方向呈现出巨大的三角形侵蚀,侵蚀最大处位于炉壳拐点部位,不同于传统的"象脚型"侵蚀。为了调查炉缸部位三角形侵蚀的原因,对炉缸的热应力分布进行了分析,发现竖直方向的正应力对炉缸的侵蚀影响较大,热应力首先集中在炉缸侧壁靠近底部的地方,侵蚀逐渐向碳砖方向发展,当碳砖完全暴露于铁水中后,在残留陶瓷杯和碳砖交界处产生了一条裂纹,该裂纹逐渐向上发展至炉壳拐点上方,待裂纹停止后,随着铁水的流动和有害元素的破坏,炉缸部位逐渐形成了巨大的三角形侵蚀。     

Study on the factors in creating the IMC-free region: dissimilar metal joining of aluminium alloys to steel by a MIG-braze welding by using the advanced hot-dip aluminized steel sheet

Dissimilar metal joining of aluminium alloys to steel is generally difficult to be in practical use because of a formation of brittle intermetallic Fe–Al compound (IMC) at the interface of the joint. The authors have been researching in order to minimize the thickness of this brittle IMC in order to get excellent joint strength and have found that the formation of this brittle IMC is regionally prevented by using the advanced hot-dip aluminized steel sheet and by adopting suitable joining conditions. In particular, this paper focuses on the mechanism of creating this IMC-free region in the case of MIG-braze welding and the results obtained are as follows. (1) The creation of IMC-free region is initiated as the first process by the dissolution of the τ₅ phase (Fe–Al–Si) in the aluminized layer into the weld metal, and temperatures of more than 886 K for dissolution during MIG-braze welding and the use of filler metal for dilution of Fe and Si in τ₅ phase have significant effects. (2) In the second process, the diffusion between aluminium-alloy weld metal and base steel is restricted by AlN on the surface thin layer of the base steel which existed under 908 K temperature conditions during MIG-braze welding.     

A phenolic antioxidant from the Pacific oyster (Crassostrea gigas) inhibits oxidation of cultured human hepatocytes mediated by diphenyl-1-pyrenylphosphine

3,5-Dihydroxy-4-methoxybenzyl alcohol (DHMBA), an antioxidant isolated from the Pacific oyster (Crassostrea gigas), was studied in a cell-based fluorometric antioxidant assay using human hepatocyte-derived cells (C3A) and diphenyl-1-pyrenylphosphine (DPPP) as a fluorescent probe. In comparison with two hydrophilic antioxidants, DHMBA showed the stronger inhibition of DPPP-mediated fluorescence than chlorogenic acid and l-ascorbic acid: at a concentration of 320 μM of DPPP, the inhibition was 26.4 ± 2.6%, 11.1 ± 1.2%, and 0 ± 2.0% for DHMBA, chlorogenic acid, and l-ascorbic acid, respectively (mean ± SD, n = 4). Their relative oxygen radical absorbance capacities (ORAC) were dissociated with their cell-based antioxidant activities: 1.47 ± 0.40, 4.57 ± 0.30, and 0.53 ± 0.13 μmol TE/μmol for DHMBA, chlorogenic acid, and l-ascorbic acid, respectively (mean ± SD, n = 4). The amphiphilicity of DHMBA was better than chlorogenic acid and l-ascorbic acid might underlie this dissociation. Since the C3A cells are human hepatoma-derived cells, DHMBA might be useful in the prevention and treatment of liver diseases by involving an oxidation process.     

Combination effect of phospholipids and n-3 polyunsaturated fatty acids on rat cholesterol metabolism

This study evaluated phospholipids (PLs) containing n-3 polyunsaturated fatty acids (n-3 PUFAs) for their specific inherent effects and effects due to a combination of the presence of glycerophosphate structure and n-3 PUFAs on cholesterol metabolism in rats. Rats were fed a diet of AIN-93G containing soybean oil (SO, 7%), SO (5.8%)+fish oil (1.2%), SO (5.2%)+soybean PLs (1.8%), SO (5.2%)+PLs containing n-3 PUFAs (1.8%), and SO (4.0%)+fish oil (1.2%)+soybean PLs (1.8%). Diets with PLs containing n-3 PUFAs, and soybean PLs in combination with fish oil, resulted in decreased serum and liver cholesterol levels through enhancement of fecal cholesterol excretion and suppression of liver sterol regulatory element binding protein-2 mRNA expression compared with the diet containing soybean oil alone. This study shows that soybean PLs with added triacylglycerol that included n-3 PUFAs have the same effects on cholesterol metabolism as PLs containing n-3 PUFAs, and that these could be of benefit to people.     

Progress in ECRF antenna development for JT-60SA

Structural, mechanical and optical design work on antennas/launchers for the electron cyclotron range of frequency heating and current drive system in JT-60 Super Advanced (JT-60SA) have been advanced based on a linear motion antenna concept. A CAD model of the launcher was built with realistic component sizes. A mock-up of the steering structure consisting of two different bellows sections for poloidal and toroidal beam scanning was fabricated to test movement of the bellows. The poloidal (?40° to +20°) and toroidal (?15° to +15°) injection angle ranges required in JT-60SA were shown to be realized by this steering structure and mirrors.