用有限元分析加热炉活动梁漏水原因及对策

通过对现场实际情况的调研，建立了加热炉水梁的平面和三维实体模型，并利用ANSYS软件给出的有限元分析结果，确定了水梁产生裂纹的根本原因，即水梁的高度偏差和在高温交变载荷作用下的受力变形。最后，根据有限元的计算结果，将原焊接结构修改为三通方式，提高了焊缝质量．延长了水梁的使用寿命。     

球团竖炉汽化冷却系统合理结构的研究

对自然循环方式的8m^2竖炉导风墙水梁、汽化冷却系统中管路结构进行计算，通过对不同上升管规格、不同水梁结构形式计算结果和冷却系统产生震动原因的分析，找出最合理的管路结构。     

竖炉导风墙水梁的设计

针对我国球团竖炉上普遍使用的导风墙水梁结构，应用平行移轴定理推导出惯性矩的计算公式；并说明水梁刚度与强度随温度变化的关系；分析了影响梁寿命的主要因素；对不焊接水梁与焊接水梁的惯性矩进行了比较。     

步进梁式加热炉活动水梁的分析与计算

运用ANSYS软件对步进梁式加热炉活动水梁进行分析计算,在其受力分析的基础上,分别计算两种工况下选用不同钢管规格的应力和位移.计算结果表明该水梁立柱具有足够的强度和刚度,并提出经验设计与有限元分析设计相结合的指导原则.     

板坯步进式加热炉水梁安装工艺

介绍了水梁模拟热状态下的安装工艺。这种安装方式改变了冷态安装预拉伸产生的应力和焊接后标高变化的不利因素。另外这种安装方式将水梁安装的理论上升到了实践,并且给检查验收提供了可以看得见摸得着的实际效果。     

延长竖炉导风墙水梁寿命的措施

昕昊达公司4台竖炉导风墙水梁采用了8根冷却水管加管壁外部堆焊设计,导风墙水梁设计及加工工艺存在一定的缺陷,严重制约了竖炉年修周期。目前竖炉年修周期为12～18个月。经过对导风墙水梁漏水原因进行分析,结合现场使用环境,重新对导风墙水梁结构进行改造,采用新的制作工艺进行加工,导风墙水梁使用寿命可延长至30个月以上。     

加热炉步进水梁开裂原因及其对策

一、前言: 广钢连轧分厂加热炉步进水梁是在消化引进技术基础上国内设计制造的,全炉有四根运动梁和五根固定梁,长度约为16米,均采用双管单回路结构,水管材质为20号钢。上管顶部焊接250X30X40MM材质为ZGCR25N120RE的耐热滑块,滑块间距为20MM。自94年4月投入使用后,于次月即发生水梁开裂漏水现象.并在随后的七个多月时间里,发生十四次二十五处基本类似的水梁开裂,误产时间达460小时。95年元月对水梁耐热滑块结构改造后进行全套水梁更换。     

延长八钢竖炉导风墙水梁使用寿命的措施

通过对八钢 8m2 竖炉导风墙水梁的问题进行分析 ,认为高速气流穿过导风墙水梁时 ,其中所含粉尘颗粒对管壁和筋板的磨损是影响水梁寿命的主要原因。为了延长水梁寿命 ,先后采取了增加水梁管径和管壁厚度 ,在水梁管壁周围增加耐火材料保护层等措施 ,并在此基础上采用了一种新的制作工艺 ,提高了水梁的使用寿命。     

步进梁加热炉钢坯横向跑偏的原因分析及解决对策

钢坯横向跑偏现象在步进梁加热炉生产中普遍存在,横向跑偏过大时会损坏炉墙,有时还会使坯料从水梁脱落造成停产事故。通过对钢坯横向跑偏的数据分析,并结合加热炉水梁的三维实体模型,利用ANSYS WORKBENCH软件给出的有限元分析结果,确定了步进梁加热炉钢坯横向跑偏的原因,即横梁焊接水平度偏差朝向一致引起的钢坯在升降过程中产生滑动位移。依此提出了打磨水梁垫块上表面的整改方案,实践验证了理论推导的正确性,坯料跑偏量下降50%,完全满足生产要求。     

竖炉汽化冷却系统管路结构的探讨

从水动力学角度对临钢8m^2竖炉导风墙水梁的自然循环冷却方式，以及汽化冷却系统中管路的结构进行了计算．分析了系统产生震动的原因，找出了最合理的管路结构。     

The role of the slope out region on fatigue crack initiation in electron beam welded waspaloy

Electron beam (EB) welding can be used to produce compressor drum assemblies for gas turbine aero-engines. The compressor disc components are fatigue limited and the weld has been identified as a fatigue susceptible region. Electron beam welds in forged and double-heat-treated WASPALOY have been characterized in terms of microstructure, hardness, and fatigue initiation for the base metal, full penetration, and partial penetration (slope-out) weld metal. It has been found that the grain size increases from the base metal through the full penetration weld to the partial penetration weld metal, being largest at the end of full penetration (EOP). Fatigue initiation was found to occur preferentially at the EOP and was associated with the presence of large sulfides at, or close to, the weld surface. The sulfides arise from free surface segregation of sulfur, from the fused metal and surface contamination (arising from a preweld sulfuric acid etching stage), into the slope-out region during weld power down. The sulfides provide fatigue initiation sites and also modify the local composition, changing the type and number density of grain-boundary carbides and γ′ precipitates, in the slope-out region near EOP, resulting in lower hardness regions. Removal of the sulfuric acid etching stage resulted in a more uniform microstructure.     

Study of welding ultra‐fine grained ferrite steel by CO2 laser

Ultra‐fine grained ferrite steels have higher strength and better toughness than the normal ferrite steels because of their micrometer or sub‐micrometer sized grains. In this paper the ultra‐fine grained steel SS400 is welded by CO₂ laser. The shape of weld, cooling rate of HAZ, width of HAZ, microstructures and mechanical properties of the joint are discussed. Experimental results indicate that laser beam welding can produce weld with a large ratio of depth to width. The cooling rate of HAZ of laser beam welding is fast, the growth of prior austenite grains of HAZ is limited, and the width of weld and HAZ is narrow. The microstructures of weld metal and coarse‐grained HAZ of laser beam welding mainly consist of B_L + M (small amount). With proper laser power and welding speed, good comprehensive mechanical properties can be acquired. The toughness of weld metal and coarse‐grained HAZ are higher than that of base metal. There is no softened zone after laser beam welding. The tensile strength of a welded joint is higher than that of base metal. The welded joint has good bending ductility.     

CO2 laser beam welding of 6061-T6 aluminum alloy thin plate

Laser beam welding is an attractive welding process for age-hardened aluminum alloys, because its low heat input minimizes the width of weld fusion and heat-affected zones (HAZs). In the present work, 1-mm-thick age-hardened Al-Mg-Si alloy, 6061-T6, plates were welded with full penetration using a 2.5-kW CO₂ laser. Fractions of porosity in the fusion zones were less than 0.05 pct in bead-on-plate welding and less than 0.2 pct in butt welding with polishing the groove surface before welding. The width of a softened region in the-laser beam welds was less than 1/4 times that of a tungsten inert gas (TIG) weld. The softened region is caused by reversion of strengthening β″ (Mg₂Si) precipitates due to weld heat input. The hardness values of the softened region in the laser beam welds were almost fully recovered to that of the base metal after an artificial aging treatment at 448 K for 28.8 ks without solution annealing, whereas those in the TIG weld were not recovered in a partly reverted region. Both the bead-on-plate weld and the butt weld after the postweld artificial aging treatment had almost equivalent tensile strengths to that of the base plate.     

金刚石锯片的激光焊接工艺

采用水平对焊的方式实现了孕镶金刚石锯片刀头与钢基间的高强度激光焊接,研究了激光焊接工艺参数对金刚石锯片焊接质量的影响,激光焊接工艺参数包括：光束模式、激光功率,焊接强度,离焦量,等离子体控制和光束偏离量。试验结果表明,光束模式,激光功率,焊接强度,离焦量,等离子体控制能显著影响激光焊接深度;光束偏离量则会影响焊缝中的气孔数量。     

Laser beam welding with filler metal

Laser beam welding generally does without the use of filler metal, in contrast to conventional welding processes. The use of filler metal in laser beam welding or in the combined GMA (g as-m etal-a rc) - laser beam - hybrid welding process widens the field of application for laser beam welding. The main advantages worthy of mention include, primarily, a greater weld gap bridging ability and a metallurgical influence on the weld metal. Based on the current state of knowledge, this article gives a few examples of different materials and material combinations the limited weldability of which is broadened when filler metal is used with laser beam welding. Listed as examples are low-alloy steels with partly elevated carbon contents, duplex steels, and the material combinations of steel/cast iron and austenite-ferrite joints. Besides laser beam welding with filler metal wire, examples of the combined GMA-laser hybrid welding process are also described.     

Influence of Water Pollution on MIC of Stainless Steel 304L

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激光焊接速度对焊缝组织和硬度分布的影响

利用激光焊接工艺焊接核级不锈钢,通过改变激光焊接速度得到不同的焊接接头.采用金相显微镜、扫描电子显微镜等手段研究了熔深比、δ/γ比、组织形貌以及焊缝中各相的成分.通过显微硬度测试了焊缝接头上硬度分布.随着焊接速度的增加,焊缝熔深比线性增加,焊缝中δ-铁素体含量增加,岛状组织增多,板条状组织增多,蠕虫状组织减少,焊缝区的平均硬度值增加.      

预热对铍环激光束钎焊过程的影响研究

研究预热对铍环激光束钎焊过程温度场和应力场分布的影响。采用轴对称模型和热力解耦的有限元方法，并假定沉积到钎缝表面的激光束能量为Gauss分布，预热通过在焊接加热前添加一个能量密度低、有效加热半径大的单独工况实现。结果表明，预热使镀环钎缝外表面焊接最高温度增加，温度梯度减小，但焊深明显增加；采用预热工况焊接后，钎缝附近塑性变形区焊接残余应力明显减小，而热影响区残余应力增大。从整体分布来看，预热使铍环外表面焊接残余应力分布均匀化。对铍环外表面钎缝附近焊接残余应力进行X射线应力测试，并与有限元分析结果对比，二者应力变化趋势基本一致。     

Stress Corrosion Cracking Behavior at Inconel and Low Alloy Steel Weld Interfaces

Three-dimensional microstructure observations, macro- to micro-scopic residual stress measurements by three methods and creviced bent beam SCC tests were performed for Inconel/low alloy steel (LAS) weld samples. The possible reasons for the suppression of SCC crack propagation near the weld interface found at a nuclear power plant were estimated to include the crack branching at the grain boundary (GB) parallel to the interface, i.e., Type II GB, compressive residual stresses in the LAS region and crack tip oxidation in the LAS at the interface. The formation mechanism of Type II GB and stress gradient in individual grains in the Inconel are also discussed.     

高炉补水次数变化的原因分析

高炉炼铁的生产过程中,冷却设备所使用的冷却水由于压力高、流量大,水质要求较高,密封装置极易损坏漏水;管道长期运行受到腐蚀,焊缝、砂眼、断裂引起漏水;闭路循环系统多处需要定期排污.冷却设备破损向高炉内漏水,影响炉况及操作.因此正确分析补水原因,对高炉长寿和生产操作、维护极其重要.