奥—贝球铁中残余奥氏体含量的研究

用Ｘ射线衍射分析仪测定了Ｓｉ、Ｃｕ、Ｍｏ含量和等温淬火温度、保温时间对奥－贝球铁中残余奥氏体含量的影响规律，在ＳＥＭ下观察分析了残余奥氏体量对试样断裂方式的影响，结果表明，Ｃｕ使残余奥氏体含量提高，Ｍｏ使残余奥氏体含量降低。一定的淬火温度、保温时间和含Ｓｉ量，可使余奥氏体含量最高值。奥氏体含量减少使断裂方向向脆性断裂转变。     

热循环对SiCp／MoSi_2复合材料性能的影响

研究了热循环对ＳｉＣｐ／ＭｏＳｉ_２复合材料抗弯强度和断裂韧度的影响，并测定了材料的宏观残余应力。实验材料是用热压方法制备的ＭｏＳｉ_２和不同体积百分数（１０，２０，３０ｖｏｌ％）ＳｉＣ_ｐ增强ＭｏＳｉ_２复合材料。实验结果表明，复合材料的抗弯强度和断裂韧度都随ＳｉＣ含量的增加而增加，经过热循环以后，四种材料的抗弯强度都有不同程度的增加，而断裂韧度则下降约２０％左右。这是由于材料经过热循环以后，造成ＳｉＣｐ和ＭｏＳｉ２界面结合过强和基体晶界过弱。尽管ＳｉＣ_ｐ和ＭｏＳｉ_２热膨胀系数相差很大，但在复合材料中未发现由此而产生的裂纹和宏观残余应力。     

热循环对SiCp／MoSi2复合材料性能的影响

研究了热循环ＳｉＣｐ／ＭｏＳｉ２复合材料抗弯强度和断裂韧度的影响，并测定了材料的宏观残余应力，实验材料是用热压方法制备了ＭｏＳｉ２和不同体积百分数（１０，２０，３０ｖｏｌ％）ＳｉＣｐ增强ＭｏＳｉ２复合材料，实验结果表明，复合材料的抗弯强度和断裂韧度都随ＳｉＣ含量的增加而增加，经过热循环以后，四种材料的抗弯强度都有不同程度的增加，而断裂韧度则下降约２０％左右，这是由于材料经过热循环以后，造成ＳｉＣｐ     

化学成分和工艺因素对奥贝球墨铸铁力学性能和组织的影响

研究了化学元素Ｃｕ、Ｓｉ以及奥氏体化温度，盐浴温度和时间对奥贝球墨铸铁力学性能和组织的影响规律，确定了在本试验条件下的最佳Ｓｉ、Ｃｕ含量及工艺参数值     

等温淬火温度对40CrMnSiMoVA超高强度钢微观组织与疲劳性能的影响

研究了４０ＣｒＭｎＳｉＭｏＶＡ钢等温淬火温度对元件轴向拉伸疲劳性能的影响。研究表明，３００℃等温淬火可降低材料对应力集中的敏感性，提高４０ＣｒＭｎＳｉＭｏＶＡ钢制复杂零件的疲劳性能。     

冷模具钢渗扩氮复合强韧化研究

研究了渗扩氮等温淬火对Ｃｒ７Ｍｏ３Ｖ２Ｓｉ和Ｃｒ１２ＭｏＶ钢、渗扩氮冷待淬火对６０Ｓｉ２Ｍｎ钢的显微组织分布、显微硬度梯度曲线的影响。结果表明，Ｃｒ７Ｍｏ３Ｖ２Ｓｉ和Ｃｒ１２ＭｏＶ钢制冷模具经渗扩氮等温淬火复合强韧化及６０Ｓｉ２Ｍｎ钢冷模具经渗扩氮冷待淬火复合强韧化处理后的使用寿命显著提高。     

准铸态工艺对贝氏体铸铁组织和性能的影响

试验研究了一定合金成分下，打箱温度、冷却介质、保温方式和保温时间等工艺因素对铸铁组织和性能影响规律。结果表明，在ＭｎＳｉＣｕＣｒ低合金化处理条件下，利用铸件浇注后的高温打箱、余热淬火及贝氏体转变温度下充分保温的准铸态工艺，可使球铁和灰铸铁基体组织稳定转变为奥贝组织为主的复相组织，并使铸铁力学性能大幅度提高。     

铁基超微晶合金的磁性,结构及稳定性研究

用Ｘ射线、ＳＥＭ和ＴＲＭ研究了ＦｅＣｕＭＳｉＢ系（Ｍ＝Ｎｂ，Ｍｏ，Ｍｎ，Ｗ，Ｎｉ）合金的表面晶化、磁性、结构和温度稳定性。发现Ｂ含量低，表面晶化严重。Ｂ、Ｓｉ和Ｍ含量影响合金的磁性。在晶化温度（Ｔｘ）附近温度下进行无磁场、纵向磁场或横向磁场退火，可以获得性能优良的高起始磁导率、高矩形比或低剩磁合金。ＦｅＣｕＭＳｉＢ系超微晶合金是由１０～３０ｎｍ的α－Ｆｅ（Ｓｉ）相（或还有少量的Ｆｅ３Ｓｉ相）和非晶相组成。上述三类性能不同的超微晶合金，显示了良好的温度稳定性。     

含硅钢下贝氏体中台阶及残余奥氏体层错的透射电镜观察

用透射电镜研究了６５Ｓｉ２ＭｎＷＡ和４０ＣｒＭｎＳｉＭｏＶＡ钢下贝氏体中台阶及残余奥氏体的精细结构。发现残余奥氏体中有大量层错，并且层错条纹与台阶具有对应关系。认为，贝氏体铁素体长大时，台阶有可能沿母相层错面直接切变增厚，而不是依靠台阶的侧向迁移来完成。     

热处理对高钒高速钢中残余奥氏体量的影响

采用铁磁性法测定了高钒高速钢中残余奥氏体量。研究了淬火温度和回火温度对高钒高速钢残余奥氏体量的影响。结果表明：淬火加热温度升高，残余奥氏体量增加；回火温度升高，残余奥氏体量降低。在试验淬火温度范围(900～1100℃)内450℃以下回火，奥氏体含量变化不明显；回火温度达到550℃时，残余奥氏体含量迅速降低。     

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.