马氏体机变的分形描述

概述了理论计算和Ｒｉｃｈａｒｄｓｏｎ作图两种测量谢宾斯基地毯分维的方法。用作图法测量了Ｆｅ－２９％Ｎｉ－０．１６％Ｃ合金冷至－１２５℃所得马氏体和残余奥氏体构成的显微组织的谢宾斯基分维。从作图法可知：（１）描述马氏体相变的谢宾斯基分维的物理意义是 ，分维值越大，残余奥氏体随马氏体尺寸减小而减少的比率越低；（２）由同一形态的马氏体和残余奥氏体构成的显微组织是否有谢宾基分维，决定于残余奥氏体面积和马氏     

铸件冒口的临界尺寸求解方法

在铸件的冒口设计中，引入了铸件与冒口接触处为非散热面这一概念，并借助铸件及冒口的形状系数，推导出铸件冒口的补缩方程（１－ε）Ｍ３ｒ－Ａｃ·Ｍｃ·Ｍ２ｒ／（Ａｃ－Ａｂ）－〔ε－Ａｂ／（Ａｃ－Ａｂ）〕·Ｖｃ／ｑｒ＝０和模数系数ｆ方程（１－ε）ｆ３－Ａｃ·ｆ２／（Ａｃ－Ａｂ）－〔ε－Ａｂ／（Ａｃ－Ａｂ）〕·ｑｃ／ｑｒ＝０。这两个方程体现了按凝固时间标准和按体积补缩能力标准计算冒口体积的一致性。采用这种方法计算出的冒口尺寸为冒口的临界尺寸     

奥氏体预变形温度对提高Fe－Mn－Si合金记忆效应的影响

本文研究了５７３─１０７３Ｋ温度范围内３％奥氏体预变形对Ｆｅ－２９．９％Ｍｎ－６．０％Ｓｉ合金记忆效应的影响．结果表明，固溶态的样品经奥氏体预变形后，在室温变形时，记忆应变（ε（ｔｒ））、应变回复率（η）及记忆应变达到饱和所对应的应变值都得到了明显的提高：随预变形温度升高，室温经约２．５％变形后应变回复率增加，并在合金动态再结晶开始温度９７３Ｋ预变形后具有最大值９８％；经９７３Ｋ预变形，合金的最大记忆应变由固溶态的１．７％提高至３．８％，完全记忆应变达２．２％；奥氏体预变形的作用在于降低了室温诱发ε马氏体的临界应力．     

低碳钢中的残余奥氏体

简介钢中尤其是低碳钢中残余奥氏体对钢的性能的重要性。叙述淬火低碳钢内条间奥氏体的形成，着重指出条状马氏体形成时存在碳的扩散。Ｍａｇｅｅ对钢中残余奥氏体量表达式不适用于低碳钢，建议应修改为：ｒ％＝ｅｘｐ［β（Ｃ１－Ｃ０）－ａ（Ｍｓ－Ｔｑ）］，并提出淬火低碳钢成分设计的一些原则。     

不锈钢焊缝金的氢脆

用慢应变速率拉伸方法研究了不稳定型奥氏体不锈钢焊缝金属（３０８Ｌ和 ３４７Ｌ）以及母材（３０４Ｌ）的氢脆敏感性,分别研究了原子氢以及氢致马氏体对氢致塑性损失的贡献,结果表明,当可扩散的氢浓度Ｃ０大于临界值（约 ２５×１０－６－３０×１０－６）后三种不锈钢均会出现氢致马氏体（ε＋α’）,其含量 Ｍ随 Ｃ０升高而升高,即 Ｍ（ε＋α’）＝５４．２－２５ ｅｘｐ（－Ｃ０／１５３）．氢致马氏体引起的塑性损失Ｉδ（Ｍ）随马氏体含量线性升高,即 Ｉδ（Ｍ）＝０４５Ｍ＝２４．４－１１．３ ｅｘｐ（－Ｃ０／１５３）１００％马氏体引起的最大塑性损失约为 ４５％,动态充氢引起的塑性损失几减去充氢除气试样的塑性损失就是原子氢引起的塑性损失Ｉδ（Ｈ）,它随 Ｃ０升高而升高,但当 Ｃ０＞１０－４后,Ｉδ（Ｈ）趋于最大值（对应 ε＝５ × １０－６／ｓ）,即 Ｉδ（Ｈ）ｍａｘ＝４４％（３０８Ｌ）,Ｉδ（Ｈ）ｍａｘ＝４５％（３４７Ｌ）以及 Ｉδ（Ｈ）ｍａｘ＝４０％（３０４Ｌ）．随应变速率ε升高,Ｉδ（Ｈ）逐渐下降,直至为零（对应 ε＝０．０１８／ｓ—０．０３２／ｓ）;即 Ｉδ（Ｈ）＝－１６．４—１０．６ ｉｇε（３０８Ｌ）,Ｉδ（Ｈ）＝－２０．９—１２．１     

中碳淬火－配分钢中的残余应力分布

利用盲孔法对分别经淬火－回火和淬火－配分处理后的Fe-0.38C-1.44Mn-1.52Si-0.61Cr试样进行了残余应力测量,结合试样的显微组织特征,研究了残余应力的分布规律。结果表明,两种试样内残余应力均介于热应力型和相变应力型之间,其沿试样厚度分布为W形。淬火－配分试样的残余应力低于淬火－回火试样,主要在于显微组织内存在高的残留奥氏体量和因配分被显著软化的马氏体基体。     

X90管线钢的微观组织和残余奥氏体稳定性分析

利用金相、扫描电镜（SEM）、电子背散射衍射（EBSD）、X射线衍射（XRD）和磁性法等手段对 X90管线钢中夹杂物、显微组织、残余奥氏体的含量、形貌及分布进行了分析,并通过分析冲击和拉伸试验前后残余奥氏体含量的变化,研究了残余奥氏体的稳定性。结果表明： X90管线钢中的夹杂物不严重,主要为 D类球状氧化物夹杂; X90管线钢的显微组织以板条贝氏体为主,也含有少量的粒状贝氏体和残余奥氏体; X90管线钢中的残余奥氏体不稳定,在冲击和拉伸试验时发生马氏体转变。     

板条马氏体钢的断裂韧性与缺口韧性拉伸塑性的关系

研究了超高强度板条马氏体钢的平面应变断裂的韧性与缺口韧性,拉伸塑性之间的关系,实验结果表明,断裂韧性受控于裂尖前沿很小范围内（１－２倍临界裂纹张开位移δｃ）显微组织的微观塑性,钝缺口韧性,拉伸塑性则受控于奥氏体晶粒尺寸或板条束直径,特征距离与裂纹尖端钝化所产生的有效变形区尺寸（２δｃ）相对应,并提出的断裂性与缺口韧性,拉伸塑性的关系取决于尖裂纹前沿有效变形区尺寸（２δｃ）与原奥氏体晶粒尺寸（ｄｒ）     

马氏体相变和形变孪晶对Fe—Mn—Si—Al钢机械性能的影响

研究了加有Ａｌ和Ｓｉ的奥氏体Ｆｅ（１５－３０ｗｔ％）Ｍｎ合金的形变孪晶，马氏体相变和机械性能，做了不同形变速率和不同温度的拉伸试验。用光镜，Ｘ射线衍射和扫描电镜观察了塑性形变过程中在γ基体中形成的孪晶，α‘（体心立方）和ε（密集六方）马氏体。     

Fe—Mn—Al合金在水溶液中电化学腐蚀行为

采用阳极极化测量，俄歇能谱仪与Ｘ射线光电子谱仪研究了Ｆｅ－（１７￣３１ｗｔ％）Ｍｎ－（０￣９ｗｔ％）Ａｌ系奥氏体合金在１ｍｏｌ／Ｌ Ｎａ２ＳＯ４与３．５％ＮａＣｌ溶液中的电化学腐蚀行为。     

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.     

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.     

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.