38MnSiVS5非调质钢转向节的热锻成形数值模拟

以丰田IMV皮卡转向节的热锻工艺为研究对象,采用Deform-3D软件对38MnSiVS5非调质钢转向节的热锻成形过程进行有限元模拟,分析了该转向节辊锻毛坯头部直径的尺寸设计对成形载荷、坯料成形充模效果的影响,研究了阻力墙在热锻成形过程中对锻坯中金属流动和充填的作用。模拟结果表明:适当增加辊锻坯料的头部直径有助于金属充模,但直径过大会导致成形载荷急剧上升;为了促进转向节头部5个叉的成形,并避免辊锻坯料直径过大,有必要通过设置阻力墙迫使金属向合理方向流动。热锻成形试验表明,优化工艺后的转向节成形锻件的充填效果得到明显改善。     

钢球毛坯热锻成形工艺设计与分析

针对钢球毛坯热锻成形的变形特点,分析了钢球毛坯热锻成形后的常见缺陷及其产生原因.以在JB31-160压力机上加工公称直径27.5mm钢球毛坯为例,分析了钢球毛坯压力机热锻成形的模具结构特点.从合理设计钢球毛坯锻件图开始,对钢球毛坯进行了有关工艺参数计算,确定了热锻钢球毛坯模具工作的部分尺寸,提出了钢球毛坯压力机热锻成形工艺设计的新方法.生产实践表明,该新工艺能显著提高热锻成形钢球毛坯的质量,降低锻件废品率,提高模具使用寿命.     

奔驰重卡转向节挤压锻造复合工艺的有限元分析

奔驰重型卡车的转向节挤压锻造工艺，分为镦粗、挤压、预锻和终锻4个工步。针对汽车转向节的挤压锻造进行的有限元分析。模拟软件采用Deform 3D，锻件采用刚塑性材料模型，成形过程看作为等温成形。报告给出了毛坯形状和尺寸、锻件形状变化，成形等效应变分布以及载荷——行程曲线等。实验表明，模拟结果和实际成形过程吻合良好。     

盘式转向节模锻的有限元模拟与实验研究

使用塑性有限元分析软件Defom3D.对盘式转向节两种坯料成形过程进行了模拟分析,通过成形过程中金属的流动情况,确定了合理的制坯形状,根据模拟确定的毛坯成功地试制出盘式转向节模锻件.有限元模拟技术通过虚拟的材料加工过程,比较和判断坯料的合理性,可以极大地节省生产成本和提高生产效率.     

万向节叉热成形过程模拟研究

建立了万向节叉热成形工艺的刚粘塑性有限元模型，分析了在不同毛坯尺寸下万向节叉热成形过程的变形情况及可能产生的缺陷，为获得合理的毛坯尺寸提供了理论依据。     

转向节预成形工艺优化设计

提出了转向节预成形优化设计新工艺.针对某转向节半封闭式锻造成形过程,利用有限元法进行了数值模拟分析,研究了坯料四个关键部位尺寸对成形质量的影响;通过模拟转向节成形过程,预测成形缺陷,确定了预成形优化工艺参数.结果表明,通过预成形优化设计,成功解决了成形过程中的缺陷,有效地降低了最大成形载荷,提高了模具寿命,在很大程度上减少了试模时间和生产成本,提高了生产效率.     

锻件内部孔洞缺陷行为的数值模拟及闭合解析

根据压力容器整体顶盖的终成形工艺,设置不同位置、不同尺寸的孔洞缺陷,采用Super Form模拟软件分析拉胀成形过程中孔洞的变形行为,确定了顶盖终成形前毛坯内部孔洞体积、尺寸变化最大的位置及终成形前毛坯内部孔洞所允许的最大体积和尺寸。同时对原始205 t钢锭中的孔洞闭合进行了解析计算,制定了合理的预锻工艺。     

非对称盒形工件拉深毛坯与成形设计

非对称盒形工件的成形一直是冲压成形工艺难点,其毛坯形状和尺寸直接影响工件成形。根据非对称盒形工件成形时受力分布,合理确定了毛坯形状,简化非对称盒形工件冲压工艺,优化了非对称盒形一次成形模具结构。     

基于有限元方法的节流阀阀体成形工艺分析及锻模设计

根据节流阀阀体的结构特点,设计了两套锻造成形方案,并利用Deform 3D软件对两套成形工艺进行了分析.根据有限元分析的结果,确定了锻造毛坯的尺寸及锻造成形的载荷,制订了合理的成形方案,为节流阀阀体的锻造生产提供了指导.     

洗手盆工艺参数模拟优化设计

针对不锈钢洗手盆的结构特点,分析计算其主要工艺参数及毛坯尺寸,运用Dynaform成形分析软件对其进行模拟,分析零件的成形工艺及其起皱、破裂缺陷,通过对毛坯形状、拉深筋尺寸及位置、模具间隙、工艺切口、润滑等进行优化,避免了成形过程中的缺陷,获得了理想的毛坯形状和工艺参数。     

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.