Ni—P化学镀层对304L钢焊接接头应力腐蚀的影响

用慢应变速率（ＳＳＲＴ）和恒载荷应力腐蚀试验方法研究了Ｎｉ－Ｐ化学镀层对３０４Ｌ钢焊接接头在４２％ＭｇＣｌ２溶液和５％ＨＣｌ溶液中的应力腐蚀（ＳＣＣ）的影响,并对镀层的最佳磷含量进行了研究。在较低的应力下,特别是在镀层不开裂的情况下,镀层能起到抗ＳＣＣ的作用;而当应力较高时或在ＳＳＲＴ下镀层破裂时,则裂纹首先在镀层破裂处产生,从而镀层失去保护作用。     

Al－1．6％Si镀层和55％－Al－Zn－1．6％Si合金镀层的缝隙腐蚀

应用电化学技术研究了Ａｌ－１．６％Ｓｉ镀层和５５％Ａｌ－Ｚｎ－１．６％Ｓｉ合金镀层在３％ＮａＣｌ溶液中的缝隙腐蚀历程。试验表明５５％Ａｌ－１．６％Ｓｉ合金镀层耐缝隙腐蚀优于Ａｌ－１．６％Ｓｉ镀层；钝化处理后，两类镀层的缝隙腐蚀孕育期延长，缝内外偶合电流减小，耐缝隙腐蚀性能有较大提高。     

304不锈钢在室温HCl＋NaCl溶液中的应力腐蚀机理

３０４不锈钢在室温ＨＣｌ＋ＮａＣｌ溶液中可发生活化态下的应力腐蚀开裂（ＳＣＣ）．ＸＰＳ成分分析表明：在酸性氯化物溶液中,试样表面形成了一层富铬的吸附产物膜,应力腐蚀裂纹的形核与这层膜的形成和Ｃｌ一局部富集有关．     

Al—1.6%Si镀层和55%Al—Zn—1.6Si合金镀层的缝隙腐蚀

应用电化学技术研究Ａｌ－１．６％Ｓｉ镀层和５５％Ａｌ－Ｚｎ－１．６Ｓｉ合金镀层在３％ＮａＣｌ溶液中缝隙腐蚀历程，试验表明５５％Ａｌ－１．６％Ｓｉ合金镀层耐缝隙腐蚀优于Ａｌ－１．６％Ｓｉ镀层；钝化处理后，两类支的缝隙腐蚀孕育期延长，缝内外偶合电流减小，耐缝隙腐蚀性能有较大提高。     

Fe的硫化物膜对UNS G11180钢在含H2S的NaCl溶液中的腐蚀行为…

通过动电位扫描和慢应变速率拉伸试验及Ｘ射线能谱技术，研究了Ｈ２Ｓ和钢铁所形成的硫化物膜对ＵＮＳ Ｇ１１８０钢在含５％ＮａＣｌ的溶液中均匀腐蚀的影响，研究结果表明：对于均匀腐蚀，无论试样施加应力与否，表面的硫化物膜对钢铁有一定的保护性，对于硫化物应力腐蚀破裂，这层膜没有明显的保护作用。     

300M钢腐蚀疲劳小裂纹扩展特性及其超载效应

在３．５％ＮａＣｌ溶液（ＳＷ）、蒸馏水和空气三种环境,两种应力比和四种应力水平的实验条件下对３００Ｍ（４０ＣｒＭｎＳｉＮｉＭｏＶ）钢腐蚀疲劳（ＣＦ）时长裂纹扩展（ＬＣＧ）和小裂纹扩展（ＳＣＧ）特性的影响进行了研究．对不同应力水平下,周期超载对３００Ｍ钢在空气与ＳＷ中的ＬＣＧ和ＳＣＧ特性的影响进行了对比研究．结果表明,晶界等微观障碍对小裂纹扩展的阻滞作用是高强钢小裂纹现象的本质原因．施加腐蚀环境,超载或提高应力水平均有利于小裂纹越过微观障碍．虽然超载显著降低长裂纹的裂纹扩展速率,但对小裂纹扩展则既可能引起迟滞效应,也可能引起加速效应．氢在晶界聚集,导致晶界脆化,可能是造成本文环境因素与力学因素对小裂纹扩展影响的一个主要原因．     

300M超高强度钢应力腐蚀敏感性及断口的分维特征

用ＷＯＬ试样研究了３００Ｍ钢在３５％ＮａＣｌ水溶液中的应力腐蚀开裂（ＳＣＣ）特性及阴极极化（偶锌）的影响，并用垂直剖面法测量了断口的分形维数。结果表明，３００Ｍ钢对中性ＮａＣｌ水溶液应力腐蚀敏感，阴极极化（ＣＰ）明显降低临界应力强度因子，但同时也使平台区裂纹扩展速率（ｄａ／ｄｔ）Ⅱ显著减小。在本文实验条件下；，断口表面为一近似分形结构，ＳＣＣ过程是使断裂面降维的过程，在临界应力强度因子附近，自然腐蚀电位（ＦＣＰ）与ＣＰ条件下的断口分维值接近，ＣＰ条件下试样中部与近表面断口分维值相近。     

热暴露和热盐暴露的交互作用对Ti811合金热盐应力腐蚀性能的影响

Ｔｉ８Ａｌ１Ｍｏ１Ｖ（Ｔｉ８１１）合金对热盐应力腐蚀（ＨＳＳＣ）较敏感,单个因素对合金ＨＳＳＣ行为影响已有研究,而复合因素的影响研究很少。采用工业生产的Ｔｉ８１１合金棒材,经双重退火后,研究了热暴露和热盐暴露的交互作用对合金ＨＳＳＣ性能的影响。结果表明：４２５℃实验条件下,热暴露和热盐暴露交互作用与单热盐应力腐蚀相比使合金的ＨＳＳＣ性能明显降低。延伸率由１８％降至６％;合金中存在位错在晶界处塞积诱发的沿晶裂纹,腐蚀产物易于在裂纹尖端积聚。导致沿晶断裂,加速腐蚀。此外,在交互作用过程中,合金中α２（Ｔｉ３Ａｌ）脆性相的析出以及晶间β相发生转变,使合金的ＨＳＳＣ敏感性增大,并加速热盐应力腐蚀。     

不均匀性对焊接接头应力腐蚀开裂的影响

通过试验，研究了模拟钢焊接接头的非均匀体在３．５％ＮａＣｌ溶液中的应力腐蚀开裂（ＳＣＣ）行为，讨论了力学不均匀性对应力腐蚀行为的影响规律，发现：（１）由于力学不均匀性的影响，由４３４０钢，１６Ｍｎ钢和Ａ３钢组成的不均匀体，其应力腐蚀裂纹的扩展速率ｄａ／ｄｔ│Ⅱ；（２）不均匀体发生ＳＣＣ的断口形貌为（沿晶＋少量撕裂纹）的混合型断口，应力强度因子Ｋ值较高或硬夹层较窄时，撕裂纹数量增加（３）１６Ｍｎ钢和     

A16061／SiCp复合材料表面Ce转化膜腐蚀行为的研究

利用金相和Ｘ射线能谱分析了Ａ１６０６１／ＳｉＣｐ复合材料表面Ｃｅ转化膜的腐蚀行为,实验表明：Ｃｅ转化膜在ＮａＣｌ溶液中的腐蚀以点钟开始,点蚀处基体为ＳｉＣ颗粒的富集区,根据Ｍａｎｓｆｅｌｄ点腐蚀模型等效电路。通过电化学阻抗谱（ＥＩＳ）研究了Ｃｅ转化膜ＮａＣｌ溶液中的腐蚀程度：转化膜在ＮａＣｌ溶液中的腐蚀程度,转化膜在ＮａＣｌ溶液中浸泡时间较短的情况下,等铲 的Ｗａｒｂｅｒｇ阻抗可忽略,可以对等效电     

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.     

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).     

Quantitative Analysis of the Crystallographic Orientation Relationship Between the Martensite and Austenite in Quenching–Partitioning–Tempering Steels

The orientation relationships(ORs)between the martensite and the retained austenite in low-and medium-carbon steels after quenching–partitioning–tempering process were studied in this work.The ORs in the studied steels are identified by selected-area electron diffraction(SAED)as either K–S or N–W ORs.Meanwhile,the ORs were also studied based on numerical fitting of electron backscatter diffraction data method suggested by Miyamoto.The simulated K–S and N–W ORs in the low-index directions generally do not well coincide with the experimental pole figure,which may be attributed to both the orientation spread from the ideal variant orientations and high symmetry of the low-index directions.However,the simulated results coincide well with experimental pole figures in the high-index directions{123}_(bcc).A modified method with simplicity based on Miyamoto’s work was proposed.The results indicate that the ORs determined by modified method are similar to those determined by Miyamoto’method,that is,the OR is near K–S OR for the low-carbon Q–P–T steel,and with the increase of carbon content,the OR is closer to N–W OR in medium-carbon Q–P–T steel.     

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.     

Growth Kinetics of Single Inclusion Particle in Molten Melts

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.