热处理对高碳低合金磨球钢的组织和性能的影响

研究了热处理工艺对高碳低合金磨球钢的显微组织、硬度、冲击韧度和耐磨性的影响，并分析了钢的耐磨性与力学性能的关系。研究结果表明，该钢具有高淬透性，在水、油中冷却的临界淬透直径均大于１００ｍｍ，回火稳定性较高。该钢经８５０￣９００℃淬火及２００℃回火后，可获得具有高硬度和一定韧性的回火马氏体组织，并具有较高的耐磨性。     

采煤机堆焊涂层截齿热处理工艺研究

35CrMnSiA钢采煤机截齿加热至930℃在10％NaOH碱液中淬火，可以获得较多的板条马氏体。通过对截齿冲击韧度、小能量多冲击抗力和截齿工作状况的分析，发现35CrMnSiA钢在370℃～410℃之间存在回火脆性，采用425℃回火，截齿强韧性较好。截齿采用先热处理而后分层堆焊的工艺，其强度、硬度和耐磨性都得到提高。     

回火温度对高温淬火态8CrMoV轧辊钢组织和性能的影响

对高温淬火态的8CrMoV轧辊钢进行不同温度回火处理,分析了回火温度对高温淬火后的8CrMoV轧辊钢的组织、显微硬度以及耐磨性的影响。结果表明:不同回火温度条件下,高温淬火态的8CrMoV钢的组织形貌、显微硬度及耐磨性具有较大的差异。随回火温度的升高,逐渐由粗大的板条状回火马氏体转变为细小的回火马氏体及回火索氏体,显微硬度逐渐降低,当回火温度达到600℃时,硬度明显降低,出现软化现象,但其耐磨性并不是严格的与硬度成正比关系,当回火温度为550℃时,其耐磨性最高。     

Cr12钢马氏体—贝氏体复合组织的力学性能

研究了Ｃｒ１２钢经９８０℃奥氏体化后，于２８０℃硝盐中等温不同时间获得不同比例的马氏体－贝氏体复合组织与力学性能的关系，并与常规淬火、回火后的力学性能进行了比较。结果表明：具有马氏体－贝氏体复合组织的Ｃｒ１２钢与常规淬火、回火的回火马氏体组织相比，除硬度有所降低外，抗弯强度、挠度、冲击韧性及耐磨性均有较大幅度的提高。经９８０℃加热、２８０℃等温５ｈ、１８０℃回火后，Ｃｒ１２钢具有最佳的综合力学性能     

Cr12钢马氏体－贝氏体复合组织的力学性能

研究了Ｃｒ１２钢经９８０℃奥氏体化后，于２８０℃硝盐中等温不同时间获得不同比例的马氏体－贝氏体复合组织与力学性能的关系，并与常规淬火、回火后的力学性能进行了比较．结果表明：具有马氏体－贝氏体复合组织的Ｃｒｌ２钢与常规淬火、回火的回火马氏体组织相比，除硬度有所降低外，抗弯强度、挠度、冲击韧性及耐磨性均有较大幅度的提高．经９８０℃加热、２８０℃等温５ｈ、１８０℃回火后，Ｃｒ１２钢具有最佳的综合力学性能．     

准贝氏体钢渗碳层耐磨性及磨损机制研究

研究了准贝氏体钢销盘磨料磨损和冲击磨料磨损的耐磨性和磨损机制，确定了回火温度对耐磨性的影响，探讨了残余奥氏体的机械稳定性及其对耐磨性的作用。结果表明：准贝氏体钢渗碳层的耐磨性接近或优于18Cr2Ni4WA钢；以微切削型磨料磨损为主的准贝氏体钢渗碳件，宜采用180℃回火，以应变疲劳型磨料磨损为主的准贝氏体钢渗碳件，宜采用280℃回火；残余奥氏体的机械稳定性对材料的耐磨性具有重要作用。对于微切削型磨料磨损，机械稳定性高的残余奥氏体不利于提高耐磨性；对于应变疲劳型磨料磨损，机械稳定性高的残余奥氏体明显提高耐磨性。     

提高Cr12MoV钢二次硬化温度的途径

Cr12MoV冷作模具钢,因其含碳量和含铬量高,具有良好的硬度、耐磨性、淬透性和回火稳定性,适应于制造要求耐磨性高,形状复杂的冷作模具.Cr12MoV钢采用1080～1120 ℃淬火加多次500～520 ℃的回火工艺处理后,易产生二次硬化现象,产品仅适用于在400～500 ℃条件下工作的耐磨模具.     

回火温度对铁基多元合金堆焊层组织及耐磨性的影响

研究了回火温度对铁基多元合金堆焊层组织及耐磨性的影响。结果表明，该堆焊层回火后具有二次硬化现象；当回火温度低于400℃，其硬度变化不明显，超过600℃，硬度明显下降；在560℃回火2h．具有优异的耐磨性，且组织与耐磨性有良好的对应。     

钢的回火时间-温度-硬度动力学关系

研究了55NiCrMoV7钢在100℃～700℃、90s～665h之间回火的组织和力学性能变化。以钢的淬、回火和退火硬度作为基本参数，定义了回火度的概念，提出了具有Johnson-Mehl-Avrami关系式形式的、适用于无二次硬化钢的回火(时效)动力学规律。由该规律出发可以推出Hollomon-Jaffe回火参数与时间、温度和硬度的关系式。     

热处理对中碳低合金铸钢强韧性和耐磨性的影响

研究了淬火和回火温度对中碳低合金耐磨铸钢组织和力学性能的影响.结果表明,经不同温度淬火、低温回火后,钢的硬度没有显著变化,达到48～51HRC.提高淬火温度有利于冲击韧度和耐磨性的提高,经 1100℃淬火 250℃回火热处理,材料可获得最佳的冲击韧度(40J/cm2)及耐磨性.用SEM分析发现,在该低应力磨料磨损工况下,实验钢的磨损形式主要有显微切削和凿坑.     

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.