挤压造型铸态薄壁铁素体球铁康明斯连接管的生产

介绍铸态薄壁铁素体球铁康明斯发动机排气连接管的生产工艺。在湿型砂挤压造型条件下，确定化学成分控制范围ω为：3．5％～3．6％C，2．6％～2．75％Si，≤0．2％Mn，≤0．07％P，≤0．03％S，≤0．1％Cu。采用球化处理及加入促进球化的合金元素铋和FeSi75人工随流孕育处理方法，不经热处理，生产出铸态满足康明斯公司工程标准CES41097铁素体球墨铸铁和CES41050—007控制选择硅量的球墨铸铁(球化率≥85％、ω为≤5％P，3．6％～4．4％Si，HB159～207，无游离碳化物)的薄壁铸件。     

薄壁铸态全铁素体球铁专用球化剂的研制

根据生产薄壁铸态全铁素体球铁的要求,考察了Mg、Ce、La、Ca、Ba、Bi、Al等元素在球铁中的作用,针对稀土镁硅铁合金的不足,采取扬长避短的设计思路,研制出一种适用于薄壁铸态铁素体球铁铸件的新型、高长效、复合、专用球化剂,用于实际后,大批量生产出QT420-15铸态全铁素体康明斯6B排气歧管.     

康明斯6BT柴油发动机铸态排气歧管生产工艺

经过分析和试验 ,开发出一种新的高效球化剂和一种新的高效复合随流孕育剂 ,制定出康明斯 6BT柴油发动机排气歧管的铸态生产工艺。经批量生产验证 ,铸态球铁排气歧管完全达到了康明斯标准规定的铁素体球铁的要求     

确保铸态铁素体球铁排气管质量的关键措施

介绍确保大批量生产的铸态铁素体球铁排气管质量达到和超过康明斯技术标准的关键措施，包括：选用特定炉料，使用专用球化剂和孕育剂，优化铁液化学成分，准确称量，严格控制球化处理，浇注及孕育等关键工序。     

康明斯6BT排气歧管铸态生产工艺的研究

经过分析和试验 ,开发出一种新的高效球化剂和一种新的高效复合随流孕育剂 ,制定出铸态生产工艺。经批量生产验证 ,取消了退火 ,铸态完全达到了康明斯标准规定的铁素体球铁的要求。     

孕育处理对树脂砂型离心铸造球铁管铸态铁素体化的影响

试验研究了孕育处理对树脂砂型离心铸造球铁管中铸态铁素体含量的影响，试验结果表明，型内孕育法浇注的球铁管试试样中铸态铁素体含量可超过９０％。     

用YHRF203呋喃树脂砂生产康明斯6BT排气歧管的研究

按照生产薄膜，铸态，全铁素体球铁件的技术要求，根据多年生产实践，研究开发出一种低粘度、低合氮量、弱吸湿性，高强度的呋喃树脂，用其配制的自硬砂用于生产康明斯6BT排气岐管上，既满足了大批量生产的各种性能要求，又解决了使用其它呋喃脂长期困扰工艺人员的一些难题。     

硅对铸态铁素体球铁低温冲击韧性的影响

研究了硅对铸态铁素体球铁低温冲击韧性的影响。试验表明,当铸态铁素体球铁硅含量增加时,脆性转变温度也相应提高;若把-40℃作为汽车在寒冷地区行驶时的低温极限,把生产技术条件所要求的冲击值60J/cm~2作为脆性转变判别值,则铸态铁素体球铁件的终硅含量上限值可取为3.0％.     

生产铸态铁素体球铁的若干经验

扼要叙及生产铸态铁素体球铁，促进铁素体的生成、机械性能指标评价等若干经验。该文对生产铸态铁素体球铁有一定参考价值。     

生产σb420MPaδ10%铸态球铁应注意的几个问题

近几年来，我厂生产的球铁件主要有工农12型手扶拖拉机配件和美国英国的阀门手轮、阀塞等铸件。球铁机械性能要求σb420MPa和δ10％。我厂原生产工艺是通过高温处理获得高韧性的铁素体球铁，因而费用高，生产周期长，效率低。为此，我厂从1992年10月开始试生产铸态铁素体球铁。试验主要用信阳#18新生铁作金属料。15炉次试验结果是抗拉强度为480～576MPa，伸长率为8．0～19．0％，石墨球化达2级，铁素体量为80～90％，硬度值小于HB178。根据生产实践结果，我们认为，生产铸态铁素体球铁应严格控制以下几个环节：1．选料与配料选料与配料是…     

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).     

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.     

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.     

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.