运用均衡凝固模数法设计液压试验平台铸铁件压边浇冒口系统

液压试验平台,材质HT200,铸件重2 800 kg,轮廓尺寸2 400 mm×1 000 mm×275 mm,平板壁厚95 mm,肋条壁厚40 mm,周边框壁厚50 mm,粘土砂,干型。选用直浇道-横浇道-压边冒口系统,运用均衡凝固收缩模数法设计压边冒口体和冒口颈尺寸,运用大孔出流理论计算压边冒口金属液充满高度。计算结果:直浇道φ75 mm,横浇道45/65 mm×70 mm,压边冒口体φ104 mm,高度200 mm,冒口颈尺寸104 mm×8 mm,冒口体浇注过程充满高度80 mm,具有挡渣能力。生产结果表明,铸件无缩孔、气孔、夹渣缺陷,铸件工艺出品率95%。实践证明采用均衡凝固收缩模数法设计液压试验平台浇冒口系统是可行的。     

运用大孔出流理论设计滚筒铸铁件顶雨淋浇注系统

梳棉机用锡林滚筒,材质HT200,轮廓尺寸φ1 318 mm×1 150 mm,壁厚22 mm,铸件重1260 kg,表干砂型。内外表面加工。为了防止铸造缺陷,运用大孔出流理论设计顶雨淋浇注系统;用收缩模数法校核浇注系统当冒口的补缩能力。设计结果：1只直浇道φ70 mm,圆环形横浇道截面50/60 mm×50 mm。批量生产表明：铸件没有气孔,夹渣及缩孔等缺陷,工艺出品率94%。实践证明：采用大孔出流理论设计浇注系统,收缩模数法校核其补缩能力,实现浇注系统当冒口的工艺是可靠的。     

运用均衡凝固理论设计液压机上横梁底雨淋式浇注系统

400 t液压机上横梁,材质HT200,铸件重4 670 kg,主要壁厚55 mm,轮廓尺寸1 818 mm×1 262 mm×730 mm,普通粘土砂手工造型,干型、干芯。运用大孔出流理论设计底雨淋式浇注系统,直浇道直径φ85 mm,位于55/65 mm×52 mm横浇道中间,两侧横浇道上均布12 mm×60 mm、长40 mm底雨淋内浇道共14只。用均衡凝固收缩模数法核算浇注系统当冒口的补缩能力。生产结果表明,铸件没有气孔、夹砂、夹渣、收缩等铸造缺陷,铸件品质稳定。实测浇注时间平均92 s,与计算值偏差1%,工艺出品率94%。生产实践证明,采用大孔出流理论设计浇注系统,用均衡凝固收缩模数法校核浇注系统的补缩功能,可以满足铸件充型和补缩要求,具有实用价值。     

148电机线圈支架灰铸铁件顶注压边浇冒口工艺的设计

148线圈支架上下为圆环,由中间9个腰肋连接,最大壁厚40 mm,铸件重70 kg,材质HT 150,普通粘土砂,水平三开箱造型。运用大孔出流理论设计了顶注压边浇冒口系统。直浇道直径φ35 mm,横浇道尺寸24/28 mm×26 mm,内浇道由截面为37/39 mm×6 mm的2道内浇道和2个压边冒口形成的55 mm×5 mm的压边缝隙合成,浇道比为A直∶A横∶A内=1.0∶1.4∶1.1。用收缩模数法设计冒口,冒口直径φ55 mm、高90 mm,设1只φ30 mm的排气耳冒口。首批生产30件,经检查无缩孔、气孔、夹砂等缺陷,铸件经加工后,全部合格,表明运用大孔出流理论设计浇注系统,采用顶注压边浇冒口填充补缩工艺,生产148线圈支架铸件是可行的。     

运用均衡凝固理论设计铸铁件升降平台的浇冒口系统

橡胶机械产品胶片机升降平台,材质HT200,重85 kg,由260/110mm×75mm圆环体与400mm×400mm×40mm方板相接组成.为防止环板交接处的收缩缺陷,采用圆环体在下、方板在上的浇注工艺.侧注式浇注系统,在浇注系统对侧安置补缩-溢流冒口.运用均衡凝固收缩模数法设计冒口尺寸,用大孔出流理论设计浇注系统.设计结果:直浇道φ35 mm,双向横浇道24/27 mm×28 mm,4道内浇道10/12 mm×34 mm,浇口截面比∑A直∶∑A横∶∑A内=1.0∶1.5∶1.6.两只冒口φ70mm×130mm,冒口颈厚7 mm,长8 mm.生产表明铸件上表面光洁,无气孔,渣孔缺陷,机加工后铸件没有缩孔、缩松缺陷,工艺出品率88.5％.证明采用均衡凝固技术设计的浇冒口系统是可靠的.     

运用均衡凝固模数法设计铸铁箱体补缩式浇注系统

轧环机下箱体,材质HT 250,重9 500 kg,轮廓尺寸4 100 mm×2 500 mm×577 mm,干砂型,冲天炉熔炼.运用均衡凝固模数法设计补缩式顶注雨淋浇注系统,以大孔出流作充填校核.采用2个浇包同时浇注,2套独立对称的浇注系统,设计结果为:直浇道φ80 mm,横浇道56/60 mm×50 mm,18只内浇道φ18 mm,浇注温度1 320～1 380 ℃.浇注出的铸件形状完整,机加后没有缩孔、缩松、夹渣、气孔等缺陷,工艺出品率93%.表明均衡凝固模数法设计补缩式浇注系统是实用的.     

套筒类铸铁件卧浇压边浇冒口工艺的设计

立柱座,套筒类铸铁件,牌号HT200,内孔直径φ203mm,外圆直径φ275mm,壁厚36mm,长840mm,法兰尺寸φ400mm,厚36mm,铸件重175kg。表干型、手工造型,冲天炉熔炼,浇注温度1320～1350℃。此类铸件常采用的工艺为立浇顶雨淋,立浇顶注搭边。根据生产经验,参考缸套铸铁件平作平浇爬芯工艺,采用卧浇压边浇冒口工艺生产,取得成功。浇冒系统由浇口杯一直浇道一横浇道一压边冒口一压边缝隙（内浇道）组成。     

球铁油缸浇注系统补缩无冒口工艺设计

球铁油缸,材质QT500-7,铸件重101 kg,外径φ270 mm,内径φ220 mm,壁厚25 mm,高750 mm,一端球面封口。采用立浇工艺,封口向上。原工艺为阶梯浇注系统,在铸件上部安放1个φ120 mm×200 mm冒口,因冒口下缩孔、浇口引入处缩松,缸壁气孔、夹渣,渗漏废品率54%。为了消除铸造缺陷,新工艺根据均衡凝固原理,采用以顶注为主的浇注系统补缩无冒口工艺,用收缩模数法设计直浇道、横浇道、内浇道尺寸,经批量生产验证,消除了缩孔、缩松、气孔、夹渣缺陷。机加工后经250 MPa×5 min水压试验无渗漏。工艺出品率从77%提高到88%。表明采用收缩模数法计算浇注系统尺寸,用浇注系统补缩的无冒口工艺是可靠的。     

耐热球铁深入煤斗铸件浇口冒口工艺设计

箱体类耐热球铁深入煤斗铸件,轮廓尺寸1 920 mm×890 mm×330 mm,璧厚25 mm,材质RQTSi-5.5,重740 kg。粘土砂干型,内腔顶面分型,铸件主要在下型,浇注系统座在芯头上。采用大孔出流理论进行充填设计:1只直浇道φ69 mm,位于横浇道中间,横浇道截面44 mm/54 mm×56 mm,6只内浇道110 mm/130 mm×6 mm。在浇注系统对面设2只溢流补缩耳冒口。用均衡凝固收缩模数法设计计算冒口,直径70 mm,高100 mm。批量生产,生产结果,没有工艺缺陷,生产稳定可靠,工艺出品率93.7%。证明采用大孔出流设计浇注系统,均衡凝固收缩模数法设计耐热球铁箱体类铸件的补缩系统是可靠的。     

运用大孔出流理论设计磨齿机床身底注式浇注系统

Y7163-10-102磨齿机床身,材质HT200,轮廓尺寸1275mm×680mm×620mm,主要壁厚20mm,最大壁厚55mm,铸件重1300kg,树脂砂型。运用大孔出流理论,设计底注式浇注系统,1个直浇道,直径φ55mm,2个横浇道,截面38mm×40mm,14个内浇道,截面29mm×8mm。浇道比为A直∶∑A横∶∑A内=1.0∶1.2∶1.4。铸件顶部放2只侧冒口,直径φ80mm。实测浇注时间80s,型腔金属液面上升速度8mm/s。生产结果表明:铸件形状完整,轮廓清晰。机加工后,铸件没有缩孔、气孔、渣孔缺陷,达到技术要求。     

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.     

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.     

Theoretical Analysis for the Motion and Temperature of Melt Droplets in Spray Degassing Process

The motion of melt droplets in spray degassing process was analyzed theoretically. The height of the treatment tank in spray degassing process could be determined by the results of theoretical calculation of motion of melt droplets. To know whether the melt droplets would solidify during spraying process, the balance temperature of melt droplets was also theoretically analyzed. Then proof experiments for theoretical results about temperature of melt droplets were carried. In comparison, the experimental results were nearly similar to the calculation results.     

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.