乌兹别克斯坦9度区某超高层建筑结构设计与优化

对于9度设防地区的超高层建筑,其结构设计基本由地震作用控制,因此抗震设计尤为重要。建筑消能减震技术可在提高结构地震安全储备的同时,降低整体工程造价,是结构优化设计的有效措施。对位于9度区的超高层建筑进行了结构方案选型对比、结构方案优化、减震设计方案比选、剪力墙内嵌钢板优化。结果显示,钢骨混凝土框架⁃核心筒方案相对于钢框架⁃支撑方案具备更高的成本优势;框架⁃核心筒方案可通过精细化设计作进一步优化;在此基础上,对钢骨混凝土框架⁃核心筒方案采用两种消能减震方案进行比选,结果表明,采用黏滞阻尼器方案的结构抗震性能明显优于采用黏滞阻尼墙方案;最后通过增大剪力墙竖向分布钢筋配筋率,对低区核心筒墙肢中的内嵌钢板进行了优化。

面向9%Ni钢大型储罐的旋转电弧窄间隙立焊装备

提出一种面向9%钢大型LNG储罐的旋转电弧窄间隙立焊装备,旨在解决LNG储罐立缝位置的焊接难题。采用窄间隙TIG旋转电弧焊接新工艺,将钨极打磨成非轴对称的尖端,通过电机控制钨极旋转,使电弧周期性加热窄间隙坡口两侧,有效解决了侧壁熔合问题。为配合该工艺,设计了新型窄间隙TIG旋转电弧焊枪,具备无线回转导电、自动送丝和双路气保护功能。同时,提出了一套适用于LNG储罐立缝位置的自动焊接设备,包括真空吸附的挂壁小车和焊接小车。在实验室搭建了全套试验装备,包括焊接小车、全自动送丝机、焊接电源等,控制焊枪立缝位置的焊接行走,防止9%Ni钢磁化,同时保证焊接过程的稳定。对24 mm厚9%Ni钢进行单层单道的焊接试验和窄间隙坡口对接试验,验证了新工艺能够解决厚板窄间隙焊接中侧壁熔合的问题,并且由于电弧循环旋转,对熔池具有搅拌作用,焊缝表面成形平滑美观。该研究为LNG储罐立缝的自动高效焊接提供了技术和装备支持。

9%Ni钢焊接技术及其焊接材料的研究现状

9%Ni钢是液化天然气(LNG)存储容器制造的主流材料,其焊接材料的选用及焊接技术是LNG存储容器的制造难点和关键点,备受关注。本文综述了不同国家9%Ni钢及其焊接材料的化学成分、力学性能等规范要求,详细分析了9%Ni钢的焊接性、焊材材料和焊接方法选用原则及焊接控制要点,并讨论了9%Ni钢焊接材料和焊接技术的发展前景。

大型LNG储罐9%Ni钢焊接质量控制探讨

以国内在建的22万m~3大型LNG储罐为例,阐述了9%Ni钢焊接的质量控制要点。对9%Ni钢焊接的母材控制、焊材管理、焊接方法、焊评,以及无损检测等要素进行了质量控制分析,简要对比了9%Ni钢手工电弧焊和全自动TT焊接的优缺点、易产生的缺陷和预防措施,对焊接过程质量控制进行了总结分析。结果表明:控制手工电弧的焊接热输入是防止裂纹产生的重要措施,手工电弧焊焊接9%Ni钢时,应尽可能采用多层、多道焊接,且层间温度控制在100℃以下;全自动TIPTIG焊接(相比手工电弧焊),焊缝外观优美,焊接一次合格率更高,焊接过程的工艺参数可追溯性强,焊接产生的烟尘少,改善了焊工的职业健康。

储罐9%Ni钢纵缝自动焊接技术应用分析

对比分析目前国内外大型LNG储罐内罐常见的焊接方式及储罐现状,介绍SMAW(Shielded Metal Arc Welding)、FCAW(Flux Cored Arc Welding)及TT焊(TIP-TIG)的优缺点。根据试验发现,TT焊工艺对9%Ni钢焊缝成型好,过渡圆滑、鱼鳞纹规则且余高较小,热影响区宽度小,枝晶分布均匀,焊丝(条)熔敷率高、坡口较多为U型,且通过已在东部沿海某试运行的LNG储罐可知,其试运行稳定,并已投入使用。

超超临界机组汽轮机转子用9%-12%Cr耐热钢研究

文章介绍了超超临界汽轮机转子用9%-12%Cr耐热钢的发展历程,重点阐述了其基体组织与强化相的研究进展,并探讨了含B的9%-12%Cr转子用中存在的问题,展望了超超临界机组汽轮机转子用耐热钢中的发展趋势。

正火冷却方式对9%Cr铁素体耐热钢组织与力学性能的影响

采取油冷和水冷2种冷却方式对9%Cr铁素体耐热钢进行正火处理,再进行回火,研究了正火冷却方式对该钢组织和力学性能的影响。结果表明:与水冷相比,油冷处理后试验钢的马氏体板条宽度较大,位错密度较小,晶界上析出的M_(23)C_(6)碳化物尺寸较小;与水冷相比,油冷处理后试验钢的屈服强度、抗拉强度、断后伸长率以及上平台冲击吸收功分别提高了9.3%,4.7%,6.1%,5.4%,韧脆转变温度降低了17.7℃,拉伸性能和冲击性能提高。

Effect of Rare Earth Elements on Austenite Growth Dynamics of Steel 9Cr2Mo

The growth dynamics of austenite grain was investigated in steel 9Cr2 Mo with different rare earth(RE)element addition.The results show that austenite grains of steel 9Cr2 Mo can be refined and their growth can be restrained by adding a certain amount of RE.According to the results,the n and Q were calculated and the mechanism of the refinement of austenite grains was discussed.

Microstructure of Steel 5Cr21Mn9Ni4N Alloyed by Rare Earth

The microstructure, composition and shape of precipitated phase under as-cast and finished product state of 5Cr21Mn9Ni4N steel with different rare earth （RE） amount were studied. Mechanical properties of 5Cr21Mn9Ni4N steels withont RE addition and with RE added by 0. 2% in mass percent were tested respectively. The results indicate that the solid solution amount of RE is about 10^-6 -10^-5 order of magnitude in 5Cr21Mn9Ni4N steel. Dendrite of as-cast condition is refined obviously and dimension of interstitial phase is shortened when RE is added by 0.10%-0.20%. But the microstructure will be coarser if surplus RE is added. Precipitated phase under finished product state distributes evenly in nearly same size with RE added by 0. 2% which leads to a largely improved high temperature mechanical property.

Deformation behaviors of 21-6-9 stainless steel tube numerical control bending under different friction conditions

For contact dominated numerical control(NC) bending process of tube, the effect of friction on bending deformation behaviors should be focused on to achieve precision bending forming. A three dimensional(3D) elastic-plastic finite element(FE) model of NC bending process was established under ABAQUS/Explicit platform, and its reliability was validated by the experiment. Then, numerical study on bending deformation behaviors under different frictions between tube and various dies was explored from multiple aspects such as wrinkling, wall thickness change and cross section deformation. The results show that the large friction of wiper die-tube reduces the wrinkling wave ratio η and cross section deformation degree ΔD and increases the wall thinning degree Δt. The large friction of mandrel-tube causes large η, Δt and ΔD, and the onset of wrinkling near clamp die. The large friction of pressure die-tube reduces Δt and ΔD, and the friction on this interface has little effect on η. The large friction of bending die-tube reduces η and ΔD, and the friction on this interface has little effect on Δt. The reasonable friction coefficients on wiper die-tube, mandrel-tube, pressure die-tube and bending die-tube of 21-6-9(0Cr21Ni6Mn9N) stainless steel tube in NC bending are 0.05-0.15, 0.05-0.15, 0.25-0.35 and 0.25-0.35, respectively. The results can provide a guideline for applying the friction conditions to establish the robust bending environment for stable and precise bending deformation of tube bending.

Study on wear resistant cast B-containing 1Cr18Ni9Ti stainless steel

The developed 1Cr18Ni9Ti austenitic stainless steel containing 1.63 wt.%B have been characterized by X-ray diffraction(XRD),electron probe microanalyzer(EPMA),optical microscopy(OM),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS)and Vickers microhardness measurement.The microstructural evolution and property of high boron stainless steel after solution treatment at the temperature of 1050℃are also investigated.The results show that the main compositions of borides are Fe,Cr and B,and with small amount of Ni,Mn and C elements.Silicon is insoluble in the borides.The hardness of borides is over 1,500 HV.It has been found that borides do not decompose during solution treatment,but part of borides dissolves into the matrix. The effect of increasing the solubility of boron element in the austenitic matrix favours the hardness enhancement by 8.54%.High boron stainless steel has excellent wear resistance in corrosive environment.Lifetime of transfer pipe made of high boron-containing stainless steel is 1.5-1.8 times longer than that of boron-free 1Cr18Ni9Ti stainless steel.

Effect of Rare Earth Elements on Quenching Crack Resistance of Steel 9Cr2Mo

The effect of rare earth elements on quenching crack resistance of steel 9Cr2Mo was investigated by means of scanning electron microscopy (SEM) and optical microscopy. Experimental results show that, by adding RE elements to steel 9Cr2Mo, the number of quenching for crack initiation is increased. Meanwhile the propagation of quenching cracks is postponed and the paths of crack propagation are changed. Therefore, quenching crack resistance can be improved by adding RE elements to steel 9Cr2Mo.

Cyclic oxidation behavior of Fe-9Cr-1Mo steel in water vapor atmosphere

The cyclic oxidation behavior of Fe-9Cr-1Mo steel (9Cr-1Mo) in 10%H2O+90%Ar (volume fraction) atmosphere at 600, 650 and 700 ℃ for various time was studied. The oxidation mechanism of 9Cr-1Mo steel in 10%H2O+90%Ar atmosphere was discussed. The thermal stress was evaluated in two oxide layers to illustrate the spallation of the oxide layer. The experimental results indicate that there exists a duplex oxide scale with an outer layer of Fe2O3 and an inner layer of mixed (Fe, Cr)3O4 formed on 9Cr-1Mo steel during cyclic oxidation. Some cracks generated in both inner and outer oxide layers. Parts of oxide scales spalled from substrate during the cyclic oxidation. A higher tensile stress in the oxide layer is formed at the early oxidation stage than at the later oxidation stage during heating. This tensile stress results in the formation of cracks in the oxide layer.

FORMATION OF PRECIPITATED AUSTENITE IN 9%Ni STEEL AND ITS PERFORMANCE AT CRYOGENIC TEMPERATURE

The formation of precipitated austenite in 9% Ni steel exposed at the temperature of α+γ re- gion and its influence on impact tonghness at cryogenic temperature have been studied. Austenite-rich and ferrite-rich bands are formed during soaking because of the re-distribu- tion of elements of C,N and Ni.The former phase is enriched of Ni,Mn,C and N,while the latter one is relatively pure.Part of the austenite formed at intermediate temperatures trans- forms into martensite when the steel is cooled down to room temperature.The complex struc- ture which consists of fine martensite and austenite exhibits a moderate strength and high enough cryogenic toughness.The austenite enriched of C,N and Ni is still stable at the cryogenic temperature.The tearing ridges on the impact fracture surface is densely occupied by the precipitated austenite,elongated along the tearing direction.One of the important cause of the excellent eryogenic properties is that the precipitated austenite absorbs the impurities and thus purifies the matrix of the steel.

Effect of Rare Earth on Thermal Shock Resistance of Steel 9Cr2Mo

The effect of rare earth elements on thermal shock resistance of cold roller steel 9Cr2Mo was investigated by means of X-ray diffractometry and optical microscopy. Experimental results show that the process of carbide precipitation of heat effect zone is restrained by adding RE elements in steel 9Cr2Mo. Therefore, thermal shock resistance of this steel can be improved.

INFLUENCE OF PHASE COMPOSITION ON PITTING CORROSION RESISTANCE OF SPUTTERED COATING OF 1Cr18Ni9Ti STAINLESS STEEL

A series of single bcc,bcc plus fcc duplex and single fcc microcrystalline coatings of 1Cr18Ni9Ti stainless steel were prepared by using sputtering technique.The resistance against pitting corrosion was studied by measurements of pitting corrosion potentials and electrochemical noise during initiation of corrosion pits.The results show that the sputtered coatings with single bcc phase or single fcc structure are more resistant to pitting corrosion than those with bcc plus fcc duplex phase structure.

Study of High Temperature Deformation and Recrystallization in W9Mo3Cr4V Steel

The behavior of high temperature deformation and recrystallization of W9Mo3Cr4V steel have been studied in this paper. Dynamic precipitation during deformation has also been investigated. In W9Mo3Cr4V steel, stress strain curves exhibit many features. The deformation structures and the effects of deformation parameters on dynamic recrystallization are more complicated than those in low alloy steels. For W9Mo3Cr4V steel, there is a large number of residual carbides on the matrix at high temperature. Also, many second carbides precipitate from the matrix during high temperature deformation. These two kinds of carbides (especially the latter) make the behavior of deformation and dynamic recrystallization in W9Mo3Cr4V steel different from those in low alloy steels. ABSTRACT:The behavior of high temperature deformation and recrystallization of W9Mo3Cr4V steel have been studied in this paper. Dynamic precipitation during deformation has also been investigated. In W9Mo3Cr4V steel, stress strain curves exhibit many features. The deformation structures and the effects of deformation parameters on dynamic recrystallization are more complicated than those in low alloy steels. For W9Mo3Cr4V steel, there is a large number of residual carbides on the matrix at high temperature. Also, many second carbides precipitate from the matrix during high temperature deformation. These two kinds of carbides (especially the latter) make the behavior of deformation and dynamic recrystallization in W9Mo3Cr4V steel different from those in low alloy steels.

High-Temperature Oxidation Behavior of 5Cr21Mn9Ni4N Steel Micro-Alloyed by Rare Earth

The oxidation resistance of 5Cr21Mn9Ni4N steel micro-alloying by RE at 700 - 900 ℃ was investigated. The results indicate that oxidation exponent n and oxidation activation energy are increased, and oxidation velocity constant kp is decreased when 0.2% RE is added in 5Cr21Mn9Ni4N steel. The addition of RE elements does not alter phase constitution of oxidation scale, however it improves the configuration of oxidation scale, and increases thermal stability and adhesivity of oxidation scale, which results in the raise of oxidation resistance of 5Cr21Mn9Ni4N steel at high temperature. The oxidation scale constitutes of refractory steel transfer from manganic oxide mostly to ferric oxide mostly with the increase of temperature, which leads to descend of compactness and desquamation resistance of oxidation scale. The mass increase of ferric oxide in the oxidation scale and the looseness of oxidation scale are the main reason to descend the oxidation resistance of refractory steel.

Hot Corrosion Behavior of Sol-Gel Nano Structured Zirconia Coated 9Cr1Mo Ferritic Steel in Alkali Metal Chlorides and Sulphates Deposit Systems at High Temperatures

Fused salt accelerated hot corrosion is quite common in gas turbines, fossil fuelled devices, waste inclinators, pyrochemical systems, etc. Presence of fused salt on metal surface dissolves their existing oxide layer. This results in an increase in oxidation rate of the metal. Since, zirconia coating is well recognized for corrosion protection under high temperature oxidative environment, we have developed zirconia coating on 9Cr1Mo ferritic steel and their oxidation performance was evaluated in LiCl-NaCl and Na2SO4-K2SO4 salts deposit system in air atmosphere at 650?C and 850?C, respectively. Before coating development, zirconium based sol was synthesized using zirconium (IV) propoxide as a precursor. Oxidation test results indicated that the zirconia coated specimens shows more than two times higher corrosion resistance in LiCl-NaCl and three time higher corrosion resistance in Na2SO4-K2SO4 salt deposit, respectively.

9度抗震设防区某54m钢管混凝土束剪力墙结构性能研究

钢管混凝土束剪力墙结构是一种新型装配式钢结构住宅体系,因在设防烈度9度地区应用钢管混凝土束剪力墙结构的经验不足,目前的《钢管混凝土束结构技术标准》(T/CECS 546—2018)中该体系的适用范围尚未纳入9度抗震设防区。以某高层住宅项目设计案例为背景,通过有限元分析与试验结果对比证明分层壳元可以较好地模拟钢管混凝土束剪力墙在罕遇地震作用下的弹塑性性能,采用结构抗震性能化设计方法对钢管混凝土束剪力墙结构在9度抗震设防区的结构性能进行了研究。结果表明通过适当加厚重要部位的钢管混凝土束剪力墙钢板厚度,该体系可用于9度抗震设防区。