Investigations into the tendency to stress corrosion of joints welded in austenitic and duplex steels

Austenitic stainless steel is welded as a cladding on the inner surface of a reactor pressure vessel (RPV) made of low alloy steel. In order to assess the structural integrity of the RPV precisely, the residual stress distribution caused by weld-overlay cladding and post-weld heat treatment (PWHT) is evaluated. Since the cladding layer is very thin compared to the vessel wall, it is necessary to evaluate the residual stress distribution around the weld fusion line, which can be very steep. In this study, cladded specimens were fabricated using different welding methods. Residual stress measurements using both sectioning and deep hole drilling (DHD) methods were then performed to evaluate the residual stress distributions through the weld fusion line. Three-dimensional thermal-elastic-plastic-creep analyses based on the finite element method were also conducted to evaluate the residual stress caused by weld-overlay cladding and PWHT. It was shown that analytical results provided reasonable agreements on weld residual stress with experimental results. It was also clarified that the main cause of residual stress due to welding and PWHT was the difference of thermal expansion between weld and base metals.     

实际开孔直径小于管口内径的压力容器开孔强度分析

针对化工设备"实际开孔直径小于管口内径"的开孔结构,采用有限元方法进行实例分析.研究发现:管口内径范围内未开孔壳体、加强短管对于开孔结构具有较大的加强作用,但加强短管尺寸不宜过大;若接管刚度大于筒体,可能引起筒体更大的变形,在结构不连续处产生更大的弯曲应力,结构加强宜采用增加筒体厚度的方式.     

Immune Cells Invade the Collateral Circulation during Human Stroke: Prospective Replication and Extension

It remains unclear if principal components of the local cerebral stroke immune response can be reliably and reproducibly observed in patients with acute large-vessel-occlusion (LVO) stroke. We prospectively studied a large independent cohort of n = 318 consecutive LVO stroke patients undergoing mechanical thrombectomy during which cerebral blood samples from within the occluded anterior circulation and systemic control samples from the ipsilateral cervical internal carotid artery were obtained. An extensive protocol was applied to homogenize the patient cohort and to standardize the procedural steps of endovascular sample collection, sample processing, and laboratory analyses. N = 58 patients met all inclusion criteria. (1) Mean total leukocyte counts were significantly higher within the occluded ischemic cerebral vasculature (I) vs. intraindividual systemic controls (S): +9.6%, I: 8114/µL ± 529 vs. S: 7406/µL ± 468, p = 0.0125. (2) This increase was driven by neutrophils: +12.1%, I: 7197/µL ± 510 vs. S: 6420/µL ± 438, p = 0.0022. Leukocyte influx was associated with (3) reduced retrograde collateral flow (R² = 0.09696, p = 0.0373) and (4) greater infarct extent (R² = 0.08382, p = 0.032). Despite LVO, leukocytes invade the occluded territory via retrograde collateral pathways early during ischemia, likely compromising cerebral hemodynamics and tissue integrity. This inflammatory response can be reliably observed in human stroke by harvesting immune cells from the occluded cerebral vascular compartment.     

The Cellular Choreography of Osteoblast Angiotropism in Bone Development and Homeostasis

Interaction between endothelial cells and osteoblasts is essential for bone development and homeostasis. This process is mediated in large part by osteoblast angiotropism, the migration of osteoblasts alongside blood vessels, which is crucial for the homing of osteoblasts to sites of bone formation during embryogenesis and in mature bones during remodeling and repair. Specialized bone endothelial cells that form “type H” capillaries have emerged as key interaction partners of osteoblasts, regulating osteoblast differentiation and maturation and ensuring their migration towards newly forming trabecular bone areas. Recent revolutions in high-resolution imaging methodologies for bone as well as single cell and RNA sequencing technologies have enabled the identification of some of the signaling pathways and molecular interactions that underpin this regulatory relationship. Similarly, the intercellular cross talk between endothelial cells and entombed osteocytes that is essential for bone formation, repair, and maintenance are beginning to be uncovered. This is a relatively new area of research that has, until recently, been hampered by a lack of appropriate analysis tools. Now that these tools are available, greater understanding of the molecular relationships between these key cell types is expected to facilitate identification of new drug targets for diseases of bone formation and remodeling.     

核电站用钢制安全壳纵焊缝的焊后热处理畸变

基于SYSWELD软件对钢制安全壳筒体环建立了有限元模型,对拟定的筒体纵焊缝热处理工艺采用有限元法进行了模拟分析,计算了热处理后的畸变和残余应力,并将数值模拟分析的畸变数据与实测数据进行了对比,证明了拟定的工艺满足产品技术要求,可为超大型容器局部焊后热处理提供参考.     

低温压力容器用SA537 CL2钢板的开发

为满足市场对低温压力容器用钢板强度高、可焊接性好、抗断裂性能优异、韧性转变温度低且生产成本低的要求,河北普阳钢铁有限公司开发了美标调质型低温压力容器用钢板SA537 CL2.其采用低碳成分设计,并添加Cr合金元素来提高钢板的淬透性;通过生产试验,获得了最佳生产工艺参数,即第1阶段开轧温度不小于1 050℃,终轧温度95...     

高压绕丝筒体预紧系数及绕丝截面研究

主要研究不同预紧系数下超高压绕丝式容器绕丝截面类型对其疲劳寿命的影响.首先基于第三强度理论计算筒体等效应力最小预紧系数ηp,并在大于ηp基础上等差选取5个预紧系数,分别计算出相应的筒体尺寸,研究预紧系数对筒体尺寸的影响;其次建立绕丝筒体结构三维有限元模型,其中针对3种钢丝截面(扁形,圆形,菱形),按照等剪应力缠绕方式计...     

药芯焊丝CO2焊在复合钢制压力容器中的应用

介绍了用药焊丝CO2焊焊接16MnR/SUS321不锈钢合钢板压力容器的焊接工艺试验及焊接工艺评定，通过检查焊缝的化学成分，硬度，金相组织，测定接头的力学性能，晶间腐蚀试验等，证明药芯焊丝CO2焊用于不锈复合钢压力容器制造是可行的，对不锈复合压力容器的焊接要点进行了简要说明。     

混合澄清槽内离子液体体系的三相流体动力学模拟

离子液体是近年来被广泛研究的新兴绿色溶剂,其在乏燃料后处理技术中具有潜在的工业应用前景。但由于缺乏对萃取反应器中离子液体流动特性的研究,制约了离子液体萃取体系的实际应用。本文以萃取工艺中广泛应用的混合澄清槽为对象,以去离子水及1-丁基-3-甲基咪唑双(三氟甲磺酰)亚胺盐（[C₄mim][NTf₂]）分别作为水相及有机相,考虑上层空气对流动行为的影响,对其混合室进行计算流体力学（computational fluid dynamics, CFD）模拟,考察不同转速、流比及温度下的有机相分布、压力场、湍动程度等。结果表明,模拟结果较好地符合实验结果,且最大误差小于6.3%;转速能直观地提升混合性能,但当超过500r/min后,继续提高转速将显著增大出口气量,从而可能对澄清室的分相性能提出更高要求;增大流比、升温均能提升350r/min转速下的有机、水相混合能力,升温还有效减小了桨力矩,但当温度超过303K时,继续升温对于桨力矩、有机相速度的改变不明显。因此,实际工艺条件建议结合升温与转速调节,在实现较好混合性能的同时,减少对澄清室分相性能的要求。本文在建立离子液体三相体系数值模拟方法的同时,为混合澄清槽的工况优化提供合理建议,并为离子液体萃取体系的深入研究提供了参考。     

直立容器支承式支座处的强度校核

根据局部应力的理论分析,提出直立容器支承式支座处强度校核的新方法。本法具有力学概念明确,分析精细,用于工程简便、实用的特点。