低氢型结构钢焊条工艺性评价方法研究

由汉诺威分析仪统计的短路时间T1〉2ms时间段内短路频率分布，反映了低氢型结构钢焊条粗熔滴短路过渡的特征。为描述这一分布，首先统计T1〉2ms时间段内短路频率分布（取0．5ms的组宽），并求出每组熔滴平均短路时间对应的累积短路频率百分数。利用最小二乘法建立熔滴累积短路频率百分数与平均短路时间（t1）之间的函数关系。最后根据得到的函数关系计算出能描述T1〉2ms时间段内短路频率分布特征的t50,以此作为判据，评价低氢型结构钢焊条的工艺性。     

大理石、萤石对不锈钢焊条熔滴过渡及熔滴中夹杂物的影响

采用水中收集熔滴、光学显微分析、电子扫描能谱分析、计算机图像分析及平板堆焊等试验方法，分别研究了大理石、萤石对不锈钢焊条熔熵过渡行为，以及它们对熔滴中非金属夹杂物及焊缝中气孔的影响。结果表明焊缝和熔滴中的非金属夹杂物呈圆球形，它们是熔滴反应区化学反应的产物，属“内生”性质；药皮中大理石含量增大时，熔滴尺寸与熔滴中夹杂物含量的波动变化存在对应关系，焊条工艺性变差，焊缝中气孔敏感性未减小；药皮中氟化稀土和萤石比值增大，熔滴细化，熔滴中夹杂物含量增大，焊条工艺性能有所改善，焊缝中气孔倾向未减小。     

焊接材料及其生产设备

20091069不锈钢焊条熔滴过渡形态和工艺性评价/王宝//焊接.-2008(8):43~46不锈钢焊条的工艺稳定性一直是影响不锈钢焊条工艺性的主要因素,是衡量不锈钢焊条工艺质量的主要标志,为了对不锈钢焊条工艺稳定性做出评价,利用汉诺威弧焊分析仪对不锈钢焊条的焊接电参数进行测试,分析焊条渣壁过渡形态的倾向大小,研究发现,不锈钢焊条渣壁过渡倾向与短路概率、熔滴的短路频率有关,据此提出以短路概率和Σn(Us),短路频率N(T1)作为不锈钢焊条工艺性评价判据,评价不锈钢焊条的工艺稳定性。实际应用表明,这一方法,可以定量判断不锈钢焊条熔滴过渡形态和科学评价不锈钢焊条工艺稳定性。图8表1参320091070不锈钢焊条熔滴过渡形态与焊接冶金学的相关性/孙咸…//电焊机.-2008,38(7):13~15,19采用高速摄影、平板堆焊等试验方法,研究了典型金红石型不锈钢焊条熔滴过渡形态及其与焊接冶金学的相关性。结果表明,金红石型不锈钢焊条有渣壁过渡和混合过渡两种基本过渡形态,前者使焊条的综合工艺性极佳;后者随混合过渡中短路过渡成分的增加,焊条工艺性变差,常用的熔滴过渡形态评定方法有4种。两种熔滴过渡形态焊接冶金学特征差别在于...     

焊接材料及其生产设备

20091069不锈钢焊条熔滴过渡形态和工艺性评价/王宝//焊接.-2008(8):43~46不锈钢焊条的工艺稳定性一直是影响不锈钢焊条工艺性的主要因素,是衡量不锈钢焊条工艺质量的主要标志,为了对不锈钢焊条工艺稳定性做出评价,利用汉诺威弧焊分析仪对不锈钢焊条的焊接电参数进行测试,分析焊条渣壁过渡形态的倾向大小,研究发现,不锈钢焊条渣壁过渡倾向与短路概率、熔滴的短路频率有关,据此提出以短路概率和Σn(Us),短路频率N(T1)作为不锈钢焊条工艺性评价判据,评价不锈钢焊条的工艺稳定性。实际应用表明,这一方法,可以定量判断不锈钢焊条熔滴过渡形态和科学评价不锈钢焊条工艺稳定性。图8表1参320091070不锈钢焊条熔滴过渡形态与焊接冶金学的相关性/孙咸…//电焊机.-2008,38(7):13~15,19采用高速摄影、平板堆焊等试验方法,研究了典型金红石型不锈钢焊条熔滴过渡形态及其与焊接冶金学的相关性。结果表明,金红石型不锈钢焊条有渣壁过渡和混合过渡两种基本过渡形态,前者使焊条的综合工艺性极佳;后者随混合过渡中短路过渡成分的增加,焊条工艺性变差,常用的熔滴过渡形态评定方法有4种。两种熔滴过渡形态焊接冶金学特征差别在于...     

双电极钛钙型焊条熔滴过渡及其影响因素

采用激光背光高速摄像系统对双电极钛钙型碳钢焊条的熔滴过渡及其影响因素进行了研究。结果表明，双电极钛钙型碳钢焊条具有细熔滴渣壁过渡、粗熔滴渣壁过渡、爆炸过渡和喷射过渡等多种熔滴过渡形式，其中细熔滴渣壁过渡占主导。双电极钛钙型碳钢焊条两芯间距、电弧电流及药皮重量系数的变化引起套筒形状发生相应变化，进而对熔滴的过渡行为产生影响。随两芯间距的减小、电弧电流的增大和药皮重量系数的增大，熔滴的过渡频率增大。     

纳米大理石对D600R堆焊焊条性能的影响

用粒径70～90nm大理石取代堆焊焊条D600R药皮中的微米大理石,制成纳米大理石焊条.利用汉诺威电弧质量分析仪对焊接过程中的电流电压和短路时间进行测试,获得微米大理石焊条和纳米大理石焊条的燃弧特征;通过焊接工艺试验、测氢试验、熔化温度测试、硬度试验、耐磨试验和微观分析,分别对两种焊条的工艺性能和力学性能进行分析.结果表明,用纳米大理石替代微米大理石可降低焊条药皮的熔化温度和堆焊层金属中的扩散氢含量;提高焊条的熔敷效率;降低焊条短路电压、短路电流概率密度和,在短路时间t12.05ms时间段内缩短累计短路时间;改善焊条操作性能;提高堆焊层金属硬度和耐磨性.     

手工电弧焊氧化还原反应动态过程的研究

本文主要研究了以大理石,萤石为主要药皮配方的手工焊条在焊接过程中药皮加热阶段,熔滴阶段和熔池阶段氧化还原反应的动态过程。了解了药皮加热时大理石释放CO_2和先期脱氧的动态规律;熔滴在刚引弧和焊接稳定后氧含量和合金含量的变化规律;熔池金属氧含量的变化规律及其各因素对各阶段反应的影响。从而得出,由于手工焊时熔池的脱氧过程不充分,所以控制焊缝氧含量的主要环节在熔滴及其以前的反应,并根据药皮氧化性的大小,又可分为以动力学为主和以热力学为主两个控制环节。     

不锈钢焊条熔滴过渡形态和工艺性评价

不锈钢焊条的工艺稳定性一直是影响不锈钢焊条工艺性的主要因素,是衡量不锈钢焊条工艺质量的主要标志,为了对不锈钢焊条工艺稳定性做出评价,利用汉诺威弧焊分析仪对不锈钢焊条的焊接电参数进行测试,分析焊条渣壁过渡形态的倾向大小,研究发现,不锈钢焊条渣壁过渡倾向与短路概率、熔滴的短路频率有关,据此提出以短路概率和Σn(Us),短路频率N(T1)作为不锈钢焊条工艺性评价判据,评价不锈钢焊条的工艺稳定性.实际应用表明,这一方法,可以定量判断不锈钢焊条熔滴过渡形态和科学评价不锈钢焊条工艺稳定性.     

高纤维素焊条的电弧物理特性分析

采用汉诺威分析仪与高速摄影仪对高纤维素焊条进行电弧物理特性分析,发现高纤维素焊条以喷射过渡为主,其工艺性的差距主要体现在熔滴颗粒度的大小。熔滴颗粒度可以通过焊条短路过渡形式体现。提出用熔滴平均短路时间、短路时间变异系数以及短路过渡频率作为判据来定量评价高纤维素焊条的工艺性。     

药皮成分对耐热钢焊条R307焊接工艺性能的影响

通过调整耐热钢R307焊条药皮中大理石/萤石的比值,对不同比值的焊条进行了断弧长度、脱渣率、飞溅率的工艺性能试验,研究了药皮中大理石/萤石的比值对R307焊条焊接工艺性能的影响。结果显示:随药皮中大理石/萤石比值的增大,焊条的断弧长度先增大后减小,比值在1.70~1.75,断弧长度达到最大值;其脱渣率先增大后减小,比值在1.75~1.80,脱渣率达到最大值;其飞溅率一直增大。综合考虑,药皮中大理石/萤石比值在1.75左右时,耐热钢焊条R307的工艺性能最好。     

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.     

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.     

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。     

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).     

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.     

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.