线能量对2205双相不锈钢焊接接头耐蚀性和韧性的影响

针对2205双相不锈钢材料，研究了线能量对其焊接接头耐蚀性和冲击韧度的影响，推荐出了12．7mm壁厚材料的焊接线能量范围，且用于某天然气管道T程现场焊接。     

固溶处理对S32750双相不锈钢焊缝组织和性能的影响

采用金相、X射线衍射、极化曲线测试、力学性能测试等方法研究了固溶处理对S32750双相不锈钢焊接钢管焊缝性能、组织的影响。结果表明,固溶处理能显著改善焊缝的低温冲击韧度和耐腐蚀性能;固溶处理前后焊缝各区域的相结构相同,但铁素体和奥氏体含量有差异,这种差异对焊缝耐蚀性的影响不大。     

22Cr双相不锈钢天然气集输管道的焊接

22Cr双相不锈铜(2205双相不锈钢)具有优良的力学性能和耐蚀性能,在石油及天然气工业、海洋工程、化学工业等行业具有广泛的用途.该材料焊接具有许多特点,工艺复杂,加上天然气管道质量要求高和现场条件的限制,现场焊接难度很大.天然气管道施工焊接是关键环节之一,在材料组织、性能及其焊接性大量试验研究的基础上,该钢首次在国内的天然气集输管道中得到了成功应用.     

双相不锈钢焊接显微组织状态

分析了铁素体与奥氏体双相不锈钢采用电子束焊和钨极氩弧焊不同热输入参数的焊接过程.在80睢500℃温度区间的不同冷却速度下试验,结果表明,全相组织没有随冷却时间的变化而发生改变;同时对焊缝热影响区显微组织的变化进行观察分析,发现不同的焊接热输入和冷却速度.使双相不锈钢焊接接头区组织性能发生变化.严格的焊接工艺和控制焊接热输入可以防止双相不锈钢焊缝区奥氏体晶粒粗大.避免在熬影响区中出现单一的铁素体组织,从而保证双相不锈钢焊接接头区具有良好的组织性能.     

含表面缺陷的双相不锈钢管道非匹配焊接接头的安全评定

采用欧洲经济共同体提出的结构完整性评定方法SINTAP(Structural integrity assessment procedure),对焊趾处含有表面裂纹(裂纹长度和深度分别为2．5mm和1．1mm)的SAF2205双相不锈钢管道非匹配焊接接头进行了安全评定。根据拉伸试验结果,建立了双相不锈钢管道焊接接头焊缝和母材的一级、二级评定曲线,测定了SAF2205钢焊接接头的低温(-18℃)断裂韧度,为安全评定提供了试验依据。评定结果表明,不论是采用一级或是二级评定,各评定点均在评定曲线定义的范围内,说明该结构是安全的。根据计算得到的极限裂纹尺寸进行了疲劳裂纹扩展寿命估算,最终疲劳寿命为0．133年。     

SAF2205双相不锈钢对接焊焊接工艺的评定

研究了SAF2205双相不锈钢在不同焊接工艺和层问温度下焊接接头的组织和力学性能.结果表明:在所采用的焊接工艺参数下,GTAW和SMAW均能得到合格的焊缝,GTAW获得的焊接接头的组织和相比例优于SMAW,冲击韧度高于SMAW.连续焊时得到的金相组织严重奥氏体化.     

2205双相不锈钢厚板TIG焊工艺研究

采用不同焊接参数对16 mm厚2205双相不锈钢进行TIG多层多道焊,焊后对焊接接头显微组织和冲击韧性进行了分析研究。结果发现,2205双相不锈钢焊接接头组织为奥氏体+铁素体,多层多道焊有助于铁素体内二次奥氏体γ2的生成;焊接接头中焊缝金属和热影响区的铁素体含量与热输入量成反比;在-40 ℃对焊接接头进行冲击试验,低韧性焊接接头的冲击断口形貌为准解理断口、高韧性焊接接头的冲击断口形貌为韧性断口,焊接接头的韧度与铁素体含量成反比。     

2205双相不锈钢与304奥氏体不锈钢的焊接

采用焊条电弧焊(SMAW),以E2209作填充材料对2205双相不锈钢与304奥氏体不锈钢异种金属焊接工艺进行研究,通过优化焊接工艺参数,获得了具有良好力学性能和合适双相比例的焊接接头.接头力学性能测试表明,拉伸试样断裂发生在强度相对较低的304母材侧;2205母材侧热影响区的显微硬度值高于焊缝和2205母材,而304...     

双相不锈钢焊接综述

该文综述了双相不锈钢的焊接特点，分析了铁素体含量对双相钢焊缝金属韧性和抗腐蚀性能的影响，对双相不锈钢的焊接材料和焊接方法作了比较全面的介绍。     

SMAW和GTAW对2205双相不锈钢焊缝组织与耐蚀性影响

研究了2205双相不锈钢在手工电弧焊(SMAW)和钨极氩弧焊(GTAW)两种焊接方法下所得焊缝的微观组织及用化学浸泡法所测得的焊缝耐蚀性.结果表明:GTAW焊缝中奥氏体相更多,且相比例更接近母材.在不同浓度下的FeCl3溶液中,GTAW焊缝比SMAW焊缝表现出更好的耐蚀性,并且GTAW焊缝耐蚀性更接近或略好于母材.     

Effects of Post-weld Heat Treatment on Microstructure,Mechanical Properties and the Role of Weld Reinforcement in 2219 Aluminum Alloy TIG-Welded Joints

In as-welded state, each region of 2219 aluminum alloy TIG-welded joint shows diff erent microstructure and microhardness due to the diff erent welding heat cycles and the resulting evolution of second phases. After the post-weld heat treatment, both the amount and the size of the eutectic structure or θ phases decreased. Correspondingly, both the Cu content in α-Al matrix and the microhardness increased to a similar level in each region of the joint, and the tensile strength of the entire joint was greatly improved. Post-weld heat treatment played the role of solid solution strengthening and aging strengthening. After the post-weld heat treatment, the weld performance became similar to other regions, but weld reinforcements lost their reinforcing eff ect on the weld and their existence was more of an adverse eff ect. The joint without weld reinforcements after the post-weld heat treatment had the optimal tensile properties, and the specimens randomly crack in the weld zone.     

The First Phase of the SRIF Industrialized Base in ＂West Area＂ Has Been Put into Operation

After nearly two years＇ tense construction, the first phase of industrialized base of Shenyang Research Institute of Foundry （SRIF）, located at the Tiexi Casting and Forging Industrial Park in the west of Tiexi District, has now been completed and formally put into operation.     

新型的治疗阿尔茨海默氏症药物(1-二甲基磷酰基-2,2,2-三氯)-乙基-1-醇烟酸醋对体外神经细胞的作用

目的: 观察本实验室合成的一种治疗阿尔茨海默氏症(AD)的药物(1-二甲基磷酰基-2, 2, 2 -三氯)-乙基^-1-醇烟酸醋(NMF),对体外培养的皮层神经细胞活性的影响以及对海人藻酸(KA)所致的神经损伤的保护作用。方法: 采用体外培养皮层神经元的方法,解剖分离 15 d胚胎小鼠皮层神经细胞, 接种于 96孔板,48 h 后加药并培养 72 h,以 MIT 法 观察 NMF 对小鼠皮层神经细胞活性的影响;同时将接种于 24 孔板的细胞预先给予 NMF,d 3 时加或不加KA处理后,以台盼蓝染色鉴别并计数死、活细胞,可得出细胞的存活率。结果: NMF 明显促进胎鼠皮层神经元活性,其中 NMF1、0. 1、10nmol·L^-1促进神经元活性增殖率分别高达 34.7%、37.4%、36. 7%, NMF 明显促进正常胎鼠皮层神经元存活卒,与对照组比较,10nmol·L^-1 NMF 对皮层神经元的存活率分别提高 39.3%、73.5%。 NMF能显著 对抗 KA 所致的神经元损伤,与 KA 损伤组相比, NMF0.1、10、10nmol·L^-1对损伤皮层神经元的保护率分别为 77.30%、80.10%、84.15%。结论: NMF 明 显促进胎鼠皮层神经元的洁性、提高正常皮层神经元,的存活卒,并能有效地保护KA所致的神经元损伤,提示 NMF 是一种很有潜力的治疗 AD 的药物。     

THERMODYNAMICS STUDY ON THE DECOMPOSITION OF CHROMITE WITH KOH

Institute of Process Engineering, Chinese Academy of Sciences, China, has proposed a method for oxidative leaching of chromite with potassium hydroxide. Understanding the mechanism of chromite decomposition, especially in the potassium hydroxide fusion, is important for the optimization of the operating parameters of the oxidative leaching process. A traditional thermodynamic method is proposed and the thermal decomposition and the reaction decomposition during the oxidative leaching of chromite with KOH and oxygen is discussed, which suggests that chromite is mainly destroyed by reactions with KOH and oxygen. Meanwhile, equilibrium of the main reactions of the above process was calculated at different temperatures and oxygen partial pressures. The stable zones of productions, namely, K2CrO4 and Fe2O3, increase with the decrease of temperature, which indicates that higher temperature is not beneficial to thermodynamic reactions. In addition, a comparison of the general alkali methods is carried out, and it is concluded that the KOH leaching process is thermodynamically superior to the conventional chromate production process.     

INFLUENCE OF HEAT TREATMENT ON DAMPING BEHAVIOUR OF THE MAGNESIUM WROUGHT ALLOY AZ61

The effect of isochronal heat treatments for 1h on variation of damping, hardness and microstructural change of the magnesium wrought alloy AZ61 was investigated. Damping and hardness behaviour could be attributed to the evolution of precipitation process. The influence of precipitation on damping behaviour was explained in the framework of the dislocation string model of Granato and Lücke.     

Three-Dimensional Growth of Coherent Ferrite in Austenite: A Molecular Dynamics Study

Coherent second phase often exhibits anisotropic morphology with specifi c orientations with respect to both the second and the matrix phases. As a key feature of microstructure, the morphology of the coherent particles is essential for understanding the second-phase strengthening eff ect in various industrial alloys. This letter reports anisotropic growth of coherent ferrite from austenite matrix in pure iron based on molecular dynamics simulation. We found that the ferrite grain tends to grow into an elongated plate-like shape, independent of its initial confi guration. The fi nal shape of the ferrite is closely related to the misfi t between the two phases, with the longest direction and the broad facet of the plate being, respectively, consistent with the best matching direction and the best matching plane calculated via the Burgers vector content(BVC) method. The strain energy calculation in the framework of Eshelby's inclusion theory verifi es that the simulated orientation of the coherent ferrite is energetically favorable. It is anticipated that the BVC method will be applicable in analysis of anisotropic growth and morphology of coherent second phase in other phase transformation systems.     

Effect of Rare Earth Doping on Impedance,Modulus and Conductivity Properties of Multiferroic Composites:0.5(BiLa_xFe_(1-x)O_3)–0.5(PbTiO_3)

The Lanthanum-doped bismuth ferrite–lead titanate compositions of 0.5(Bi LaxFe1-xO3)–0.5(Pb Ti O3)(x = 0.05,0.10,0.15,0.20)(BLxF1-x-PT) were prepared by mixed oxide method.Structural characterization was performed by X-ray diffraction and shows a tetragonal structure at room temperature.The lattice parameter c/a ratio decreases with increasing of La(x = 0.05–0.20) concentration of the composites.The effect of charge carrier/ion hopping mechanism,conductivity,relaxation process and impedance parameters was studied using an impedance analyzer in a wide frequency range(102–106Hz) at different temperatures.The nature of Nyquist plot confirms the presence of bulk effects only,and non-Debye type of relaxation processes occurs in the composites.The electrical modulus exhibits an important role of the hopping mechanism in the electrical transport process of the materials.The ac conductivity and dc conductivity of the materials were studied,and the activation energy found to be 0.81,0.77,0.76 and 0.74 e V for all compositions of x = 0.05–0.20 at different temperatures(200–300 °C).     

Using Finite Element and Contour Method to Evaluate Residual Stress in Thick Ti-6Al-4V Alloy Welded by Electron Beam Welding

This work was to reveal the residual stress profile in electron beam welded Ti-6Al-4V alloy plates(50 mm thick) by using finite element and contour measurement methods.A three-dimensional finite element model of 50-mmthick titanium component was proposed,in which a column–cone combined heat source model was used to simulate the temperature field and a thermo-elastic–plastic model to analyze residual stress in a weld joint based on ABAQUS software.Considering the uncertainty of welding simulation,the computation was calibrated by experimental data of contour measurement method.Both test and simulated results show that residual stresses on the surface and inside the weld zone are significantly different and present a narrow and large gradient feature in the weld joint.The peak tensile stress exceeds the yield strength of base materials inside weld,which are distinctly different from residual stress of the thin Ti-6Al-4V alloy plates presented in references before.     

Microstructures and Tensile Properties of Ultrafine-Grained Ni–(1–3.5) wt% SiC_(NP) Composites Prepared by a Powder Metallurgy Route

Silicon carbide nanoparticle-reinforced nickel-based composites(Ni–Si CNP),with a Si CNPcontent ranged from1 to 3.5 wt%,were prepared using mechanical alloying and spark plasma sintering.In addition,unreinforced pure nickel samples were also prepared for comparative purposes.To characterize the microstructural properties of both the unreinforced pure nickel and the Ni–Si CNPcomposites transmission electron microscopy(TEM) was used,while their mechanical behavior was investigated using the Vickers pyramid method for hardness measurements and a universal tensile testing machine for tensile tests.TEM results showed an array of dislocation lines decorated in the sintered pure nickel sample,whereas,for the Ni–Si CNPcomposites,the presence of nano-dispersed Si CNPand twinning crystals was observed.These homogeneously distributed Si CNPwere found located either within the matrix,between twins or on grain boundaries.For the Ni–Si CNPcomposites,coerced coarsening of the Si CNPassembly occurred with increasing Si CNPcontent.Furthermore,the grain sizes of the Ni–Si CNPcomposites were much finer than that of the unreinforced pure nickel,which was considered to be due to the composite ball milling process.In all cases,the Ni–Si CNPcomposites showed higher strengths and hardness values than the unreinforced pure nickel,likely due to a combination of dispersion strengthening(Orowan effects) and particle strengthening(Hall–Petch effects).For the Ni–Si CNPcomposites,the strength increased initially and then decreased as a function of Si CNPcontent,whereas their elongation percentages decreased linearly.Compared to all materials tested,the Ni–Si CNPcomposite containing 1.5% Si C was found more superior considering both their strength and plastic properties.     

Directional Growth of Tin Crystals Controlled by Combined Solute Concentration Gradient Field and Static Magnetic Field

A new method was introduced to achieve directional growth of Sn crystals. Microstructures in liquid(Pb)/liquid(Sn) diffusion couples were investigated under various static magnetic fields. Results show that the β-Sn crystals mainly reveal an irregular dendritic morphology without or with a relatively low static magnetic field(B0.3 T). When the magnetic field is increased to 0.5 T, the β-Sn dendrites close to the final stage of growth begin to show some directional character. With a further increase in the magnetic field to a higher level(0.8–5 T), the β-Sn dendrites have an enhanced directional growth character, but the dendrites show a certain deflection. As the magnetic field is increased to 12 T, the directional growth of the β-Sn dendrites in the center of the couple is severely destroyed. The mechanism of the directional growth of the β-Sn crystals and the deflection of the β-Sn crystals with the application of static magnetic field was tentatively discussed.