灰铸铁贝氏体等温淬火研究

研究了等温淬火热处理工艺对灰铸铁组织和性能的影响,并确定了860℃保温2h,然后在300℃保温1.5h的等温淬火工艺,在此工艺条件下可获得贝氏体基体的高性能灰铸铁。     

等温淬火对灰铸铁组织和性能的影响

研究了等温淬火热处理工艺对灰铸铁组织和性能的影响，并确定了860℃保温2h，然后在300℃保温1.5h的等温淬火热处理工艺，在此热处理工艺条件下可获得帆氏体基体的高性能灰铸铁。     

等温淬火对水利工程用YP460钢的组织与力学性能的影响

研究了等温淬火温度和保温时间对YP460钢的显微组织、物相组成、硬度和冲击性能的影响,优化了等温淬火工艺。结果表明:淬火态、250~300℃和325℃等温淬火态YP460钢的显微组织分别为马氏体+残余奥氏体、下贝氏体+残余奥氏体和上贝氏体+残余奥氏体;当等温温度为250、275和300℃时,随着等温保温时间的延长,洛氏硬度呈现逐渐增加的趋势而冲击韧性呈现逐渐降低的特征;而当等温温度为325℃时,洛氏硬度随着保温时间的延长逐渐降低而冲击韧性逐渐升高;相同等温保温时间下,325℃等温淬火态试样的洛氏硬度和冲击韧性都要低于250~300℃等温淬火态试样;YP460钢适宜的等温淬火工艺为300℃保温4~8 h。     

双相ADI飞轮毂热处理工艺

探索了双相ADI飞轮等温淬火热处理工艺,认为双相ADI奥氏体含碳量低,需要加入更多的合金元素以增强淬透性;共析铁素体对双相ADI力学性能的影响相比奥铁体更敏感。飞轮最佳热处理工艺为奥氏体化840℃保温1.5 h,等温淬火320℃保温1 h.     

蠕墨铸铁等温淬火工艺及性能的试验研究

以蠕墨铸铁为对象,研究了等温淬火工艺对材料室温力学性能、高温力学性能、热稳定性及冷热疲劳性的影响。结果表明:较佳的等温淬火工艺为:(850～880℃)×1.5 h+290℃×1.5h;等温淬火蠕铁常温至300℃,抗拉强度提高1倍以上,600℃时材料抗拉强度下降较多;等温淬火蠕铁在300～400℃温度下的金相组织与保温时间基本无关,等温淬火蠕铁的冷热疲劳性能优于普通蠕铁。     

奥氏体等温淬火灰口铸铁

选用三种牌号灰铸铁 （ Ｈ Ｔ１５０ 、 Ｈ Ｔ２００ 、 Ｈ Ｔ２５０） , 采用不同热处理 （９００ ℃奥氏体化后, 在２８０ ℃、３２０ ℃、３７０ ℃下进行等温淬火） 后, 分析了热处理后的力学性能等与等温温度的关系; 通过对亚共晶、过共晶灰铸铁等淬后性能的对比, 发现过共晶灰铸铁热处理后性能提高幅度虽不如亚共晶灰铁, 但仍有一定改善; 应用表明, 奥氏体等温淬火工艺应用于灰铸铁件, 获得的奥贝灰铁件兼具较好的抗拉强度和耐磨性。     

等温淬火对灰铸铁组织和性能的影响

系统地研究了等温淬火对灰铸铁组织和性能的影响，并确定了其最佳的等温淬火工艺规范。结果表明：多温湿度是影响灰铸铁组织和性能的关键因素。     

等温淬火工艺对高碳钢组织与性能的影响

通过调整奥氏体化温度和保温时间、等温温度和等温时间等工艺参数,研究了等温淬火工艺对高碳钢组织与性能的影响。结果表明,高碳钢适宜的等温淬火工艺为900℃×30 min奥氏体化+盐浴300℃×40 min。     

两步法等温淬火工艺对等温淬火球铁组织和性能的影响

通过硬度测试、韧性试验和显微组织比较,在不同的工艺条件下,对比研究了两步法和传统的单步法等温淬火工艺条件下得到的等温淬火球铁(ADI)的组织和性能.结果表明,采用"低温285℃保温形核 高温340℃或370℃等温淬火"的两步法等温淬火工艺与传统的340℃或370℃单步法等温淬火工艺相比,两步法得到的ADI比传统的单步法得到的ADI试样微观组织更细化、硬度显著提高、韧性也有了明显的改善.     

热处理工艺对低合金钢组织和性能的影响

对低合金钢试样进行了不同的热处理工艺试验.试验结果表明:在920℃奥氏体化保温1h条件下,采用油冷时,低合金钢具有较好的韧性和硬度.采用空冷时,具有较好的韧性但硬度不高.采用315℃等温淬火,等温淬火时间为30min时,强韧性达到良好的配合.     

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.